GRB130427A

This page lists all entries on GRB130427A in GRBweb

Summary Fermi GBM IPN Swift Fermi LAT GCN 14448 GCN 14449 GCN 14450 GCN 14451 GCN 14452 GCN 14453 GCN 14454 GCN 14455 GCN 14456 GCN 14457 GCN 14458 GCN 14459 GCN 14462 GCN 14463 GCN 14464 GCN 14465 GCN 14466 GCN 14468 GCN 14470 GCN 14471 GCN 14472 GCN 14473 GCN 14474 GCN 14475 GCN 14476 GCN 14478 GCN 14480 GCN 14481 GCN 14482 GCN 14483 GCN 14484 GCN 14485 GCN 14486 GCN 14487 GCN 14488 GCN 14489 GCN 14490 GCN 14491 GCN 14492 GCN 14494 GCN 14495 GCN 14497 GCN 14498 GCN 14502 GCN 14503 GCN 14505 GCN 14506 GCN 14507 GCN 14508 GCN 14509 GCN 14510 GCN 14511 GCN 14513 GCN 14514 GCN 14515 GCN 14516 GCN 14517 GCN 14518 GCN 14519 GCN 14520 GCN 14521 GCN 14522 GCN 14523 GCN 14525 GCN 14526 GCN 14534 GCN 14538 GCN 14549 GCN 14579 GCN 14582 GCN 14590 GCN 14592 GCN 14596 GCN 14597 GCN 14598 GCN 14605 GCN 14606 GCN 14608 GCN 14615 GCN 14617 GCN 14631 GCN 14645 GCN 14646 GCN 14662 GCN 14666 GCN 14669 GCN 14672 GCN 14673 GCN 14686

Summary table
Variable Value Source
GRB_name_Fermi GRB130427324
T0 7:47:06 UTC Fermi_LAT
ra 173.1360° Swift
decl 27.6977° Swift
pos_error 4.53e-04° Swift
T90 138.242 s Fermi_GBM
T90_error 3.238 s Fermi_GBM
T90_start 7:47:10.516 UTC Fermi_GBM
fluence 2.46e-03 erg/cm² Fermi_GBM
fluence_error 1.24e-06 erg/cm² Fermi_GBM
redshift 0.3400
T100 213.83 s
GBM_located False
mjd 56409.324375 Fermi_LAT
Fermi GBM table
GRB_name_Fermi GRB130427324
trigger_name bn130427324
ra 173.1358°
decl 27.7128°
pos_error 2.45e+00°
datum 2013-04-27
t_trigger 7:47:06.420 UTC
T90 138.242 s
T90_error 3.238 s
T90_start 7:47:10.516 UTC
fluence 2.46e-03 erg/cm²
fluence_error 1.24e-06 erg/cm²
flux_1024 1.05e+03 erg/cm²/s
flux_1024_error 2.21e+00 erg/cm²/s
flux_1024_time 7.49e+00 erg/cm²/s
flux_64 1.26e+03 erg/cm²/s
flux_64_error 1.05e+01 erg/cm²/s
IPN table
GRB_name GRB130427A
ra 173.1375°
decl 27.6833°
pos_error 5.00e-02°
redshift 0.3399
Swift table
GRB_name GRB130427A
t_trigger 7:47:57 UTC
ra 173.1360°
decl 27.6977°
pos_error 4.53e-04°
T90 162.83 s
fluence 3.10e-04 erg/cm²
redshift 0.3400
Fermi LAT table
GRB_name_Fermi GRB130427324
GRB_name GRB130427A
MET 388741629.0
datum 2013-04-27
t_trigger 7:47:06 UTC
ra 173.1360°
decl 27.7129°
pos_error 1.30e-03°
GCN 14448 table
GRB_name GRB130427A
GCN_number 14448
Detection_method Swift Det
t_trigger 7:47:57 UTC
ra 173.1390°
decl 27.6920°
Circular_text TITLE: GCN CIRCULAR NUMBER: 14448 SUBJECT: GRB 130427A: Swift detection of a very bright burst with a likely bright optical counterpart DATE: 13/04/27 08:24:13 GMT FROM: David Palmer at LANL A. Maselli (INAF-IASFPA), A. P. Beardmore (U Leicester), A. Y. Lien (NASA/GSFC/ORAU), V. Mangano (INAF-IASFPA), C. J. Mountford (U Leicester), K. L. Page (U Leicester), D. M. Palmer (LANL) and M. H. Siegel (PSU) report on behalf of the Swift Team: At 07:47:57 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 130427A (trigger=554620). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 173.139, +27.692 which is RA(J2000) = 11h 32m 33s Dec(J2000) = +27d 41' 29" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows an extremely bright complex peak about 20 seconds long starting at T-50, while Swift was slewing from the previous pre-planned target, followed by a smaller peak during the slew to the burst with emission through at least T+200. The peak count rate was ~ 100,000 counts/sec (15-350 keV), at T-40 sec, before the trigger. The XRT began observing the field at 07:50:17.7 UT, 140.2 seconds after the BAT trigger. XRT found a bright, uncatalogued X-ray source located at RA, Dec 173.1362, 27.7129 which is equivalent to: RA(J2000) = +11h 32m 32.69s Dec(J2000) = +27d 42' 46.4" with an uncertainty of 4.7 arcseconds (radius, 90% containment). This location is 75 arcseconds from the BAT onboard position, within the BAT error circle. No event data are yet available to determine the column density using X-ray spectroscopy. UVOT took a finding chart exposure of 150 seconds with the White filter starting 147 seconds after the BAT trigger. A blurred bright source appears to be located near the XRT position in the initial 2.7'x2.7' sub-image. However, the lack of reference stars and lack of star tracker lock prevents a definitive identification and the measurement of a position or magnitude. This is an extremely bright burst in all three instruments, and it was also seen by Fermi/GBM. After the slew to the burst, the star trackers had trouble locking on to give a spacecraft attitude, so the XRT position may be inaccurate at the arcminute level. The apparent optical counterpart appears extremely blurred, possibly due to the lack of star tracker lock, but more likely to be due to instrumental effects on a very bright optical counterpart. Further follow-up is warranted for all ground-based observatories. Burst Advocate for this burst is A. Maselli (maselli AT ifc.inaf.it). Please contact the BA by email if you require additional information regarding Swift followup of this burst. In extremely urgent cases, after trying the Burst Advocate, you can contact the Swift PI by phone (see Swift TOO web site for information: http://www.swift.psu.edu/too.html.)
GCN 14449 table
GRB_name GRB130427A
GCN_number 14449
Detection_method Swift-BAT Det
Circular_text TITLE: GCN CIRCULAR NUMBER: 14449 SUBJECT: GRB 130427A: P60 early nondetection DATE: 13/04/27 08:39:09 GMT FROM: Daniel Perley at Caltech D. A. Perley (Caltech) reports on behalf of a larger collaboration: The Palomar 60-inch telescope automatically responded to GRB 130427A (Maselli et al., GCN 14448) and began taking observations at 07:52:22 UT (4.42 minutes after the BAT trigger). A series of 60-second images were taken in r, i, and z filters; observations are still ongoing. Inspection of individual frames shows no detection of an optical transient consistent with the XRT position to approximately r > 20.6 mag, i > 20.7 mag, z > 19.7 mag. Nondetection of an afterglow in rapidly-triggered P60 observations is unusual (Cenko et al. 2009, ApJ 693, 1484), especially in the presence of an very bright GRB and early XRT afterglow. This is suggestive of a highly extinguished (or possibly high-redshift) burst, and may indicate that the possible UVOT source reported by Maselli et al. was spurious. Further observations, especially in the NIR, are strongly encouraged.
GCN 14450 table
GRB_name GRB130427A
GCN_number 14450
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 14450 SUBJECT: GRB 130427A: early optical observations DATE: 13/04/27 08:46:41 GMT FROM: Alexei Pozanenko at IKI, Moscow L. Elenin (KIAM), A. Volnova ( IKI), V. Savanevych (KNURE), A. Bryukhovetskiy (NSFCTC), I. Molotov (KIAM), A. Pozanenko (IKI) report on behalf of larger GRB follow-up collaboration: We started observation of the field of the Swift GRB 130427A (Maselli et al., GCN 14448) with 0.45-m telescope of ISON-NM observatory on Apr. 27 (UT) 07:50:17. On the first images of 30 s exposure we identified very bright optical counterpart of GRB 130427A (Maselli et al., GCN 14448) at about 12m in the intitial images. The coordinates of the counterpart are (J2000) 11 32 32.84 +27 41 56.2 with uncertainties of about 1". Observations are continuing.
GCN 14451 table
GRB_name GRB130427A
GCN_number 14451
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 14451 SUBJECT: GRB 130427A: P60 early detection DATE: 13/04/27 08:56:29 GMT FROM: Daniel Perley at Caltech D. A. Perley (Caltech) reports on behalf of a larger collaboration: Upon further inspection of the P60 images, we identify a very bright optical source separated by about 51 arcseconds from the XRT afterglow location but consistent with the optical afterglow location reported by Elenin et al. (GCN 14450) The source is saturated in the early images. Further observations are ongoing. We also note that there is an SDSS galaxy at this position, suggesting a low-redshift event.
GCN 14452 table
GRB_name GRB130427A
GCN_number 14452
Detection_method Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 14452 SUBJECT: GRB 130427A: Faulkes Telescope North detection DATE: 13/04/27 09:21:48 GMT FROM: Cristiano Guidorzi at Ferrara U,Italy A. Melandri (INAF-OAB), C. Guidorzi (U. Ferrara), A. Gomboc, J. Japelj (U. Ljubljana), C.G. Mundell (LJMU) report on behalf of a larger collaboration: The 2-m Faulkes Telescope North robotically followed up GRB130427A (SWIFT trigger 554620, Maselli et al. GCN 14448 ) starting 4.3 min after the GRB trigger time. We detect a bright fading source at the position reported by Elenin et al. (GCN 14450), Perley (GCN 14451) with R ~11.5 mag. We note also a faint, 21-mag, underlying source visible in SDSS images that may suggest this GRB is nearby with a bright host galaxy. Observations are ongoing.
GCN 14453 table
GRB_name GRB130427A
GCN_number 14453
Detection_method correction
Circular_text TITLE: GCN CIRCULAR NUMBER: 14453 SUBJECT: GRB 130427A: PAIRITEL NIR Detections DATE: 13/04/27 09:47:41 GMT FROM: Adam Morgan at U.C. Berkeley A. N. Morgan (UC Berkeley) reports: We observed the field of GRB 130427A (Maselli et al., GCN 14448) with the 1.3m PAIRITEL located at Mt. Hopkins, Arizona. Observations began at 2013-Apr-27 07h59m24s UT, 11.45 minutes after the Swift Trigger. In preliminary mosaics (consisting of 75 ~8 second images for a total effective exposure time of 9.75 minutes) taken simultaneously in the J, H, and Ks filters, we detect the optical afterglow (Elenin et al., GCN 14450; Perley, GCN 14451; Melandri et al., GCN 14452). The preliminary photometry yields: post burst t_mid (hr) exp.(m) filt mag m_err 0.36 9.75 J 12.13 0.03 0.36 9.75 H 11.75 0.04 0.36 9.75 Ks 11.02 0.08 Observations continued until the source passed beyond telescope limits. All magnitudes are given in the Vega system, calibrated to 2MASS. No correction for Galactic extinction has been made to the above reported values.
GCN 14454 table
GRB_name GRB130427A
GCN_number 14454
Detection_method MITSuME
Circular_text TITLE: GCN CIRCULAR NUMBER: 14454 SUBJECT: GRB 130427A: MITSuME Akeno Optical observation(T0+8000s~) DATE: 13/04/27 11:19:18 GMT FROM: Yoichi Yatsu at Tokyo Tech. Y. Yatsu, Y. Yano, R. Usui, Y. Tachibana, K. Ito, T. Yoshii, S. Kurita, Y. Saito, and N. Kawai (Tokyo Tech) report on behalf of the MITSuME collaboration: We observed GRB 130427A (Maselli et al., GCNC 14448) with an optical tri-color (g, Rc, and Ic) camera attached to the MITSuME 50 cm telescope of Akeno Observatory, Yamanashi, Japan. The observation started on 2013-04-27 10:06:09.60 UT (8293 sec after the trigger). And we found the optical counterpart reported in the twilight sky. The measured magnitudes were listed below. MID-MJD T-EXP[sec] g' Rc Ic ------------------------------------------------------------------------------------------- 56409.4231929 360 15.66+/-0.10 15.03+/-0.07 14.71+/-0.09 ------------------------------------------------------------------------------------------- T-EXP: Total Exposure time [sec] (The photon flux were calibrated against GSC2.3 catalog.)
GCN 14455 table
GRB_name GRB130427A
GCN_number 14455
Detection_method Other
redshift 0.3400
Circular_text TITLE: GCN CIRCULAR NUMBER: 14455 SUBJECT: GRB 130427A: Gemini-North redshift DATE: 13/04/27 11:43:31 GMT FROM: Andrew Levan at U.of Leicester A.J. Levan (U. Warwick), S.B. Cenko (U.C. Berkeley), D.A. Perley (Caltech) and N.R. Tanvir (U. Leicester) report for a larger collaboration: We obtained spectroscopy of the afterglow of GRB 130427A (Maselli et al. GCN 14448, Elenin et al. GCN 14450, Perley et al. GCN 14451) with Gemini-North / GMOS, begininnig at 09:19 UT roughly 1.5 hours after the burst. Two different central wavelengths were observed giving a coverage from ~3100-6700 A. The resulting spectra are of very high signal to noise given the brightness of the afterglow. In these spectra we identify absorption lines due to Ca H and K, Mg I as well as the Mg II doublet at a common redshift of z=0.34. We suggest this to be the redshift of GRB 130427A. We do not see evidence for emission lines from an underlying host, although given the brightness of the afterglow this is not surprising. The absolute magnitude of object in SDSS, if at z=0.34 is M_R ~ -19.7, relatively bright for a GRB host. We thank the Gemini-staff for their help in rapidly obtaining these observations.
GCN 14456 table
GRB_name GRB130427A
GCN_number 14456
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 14456 SUBJECT: GRB 130427A: Continued P60 follow-up of an extremely bright optical afterglow DATE: 13/04/27 11:52:44 GMT FROM: S. Bradley Cenko at Caltech D. A. Perley (Caltech) and S. B. Cenko (UC Berkeley) report: We have continued observations of the afterglow of GRB130427A (Maselli et al., GCN 14448) with the Palomar 60-inch telescope until the field set. Relative to SDSS reference stars in the field, in some select recent images we estimate afterglow magnitudes of: r' = 14.86 mag (t = 1.40 hours) r' = 15.32 mag (t = 2.31 hours) r' = 15.55 mag (t = 3.10 hours) This is brighter (by about 1 mag) than any other Swift burst as measured at similar epoch (as of 2010; Kann et al. ApJ 720:1513), though still significantly fainter than GRB 030329 which reached approximately 13 mag at 0.1 day. The rate of fading corresponds to a relatively shallow decay index of approximately alpha~-0.85, suggesting that this afterglow will remain bright for an extended period. Worldwide small-telescope follow-up (including by amateurs) is strongly encouraged.
GCN 14457 table
GRB_name GRB130427A
GCN_number 14457
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 14457 SUBJECT: GRB 130427A: iTelescope T11 optical observations DATE: 13/04/27 12:26:03 GMT FROM: Veli-Pekka Hentunen at Taurus Hill Obs,A95 Veli-Pekka Hentunen, Markku Nissinen and Tuomo Salmi (Taurus Hill Observatory, Varkaus, Finland) report: We have detected GRB 130427A optical afterglow at iTelescope observatory T11 (Mayhill, New Mexico) 0.50-m/6.8 astrograph and FLI ProLine PL11002M CCD. Three unfiltered and three photometric V filter images with 120 sec exposure time were made. The afterglow was detected at following position RA 11:32:32.83 and DEC +27:41:56.4 The following magnitudes were obtained from the observations using NOMAD1 1176-0248446 (R=13.520, V=13.120) as the comparison: Tmid(sec)+T0 Filter Exp. time Mag Mag err. 4597 unfiltered 120 15.02CR 0.04 4743 unfiltered 120 15.09CR 0.05 4887 unfiltered 120 15.11CR 0.05 5438 V 120 14.89V 0.04 5582 V 120 14.89V 0.04 5726 V 120 14.86V 0.04
GCN 14458 table
GRB_name GRB130427A
GCN_number 14458
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 14458 SUBJECT: GRB 130427A: Weihai optical observations DATE: 13/04/27 13:08:24 GMT FROM: Dong Xu at DARK/NBI D. Xu (DARK/NBI), C. Cao, S.-M. Hu, C.-M. Zhang (SDU) report: We observed the field of GRB 130427A (Maselli et al., GCN 14448) with the 1m telescope located in Weihai, Shandong Province, China. A series of I-, R-, V-, and B-band frames were obtained, and observations are still ongoing. Although under quite much cloud, at the afterglow position (Elenin et al., GCN 14450; Perley, GCN 14451) we detect the optical counterpart with R=15.5 mag, with a median time of 4.178 hr after the BAT trigger and calibrated with nearby USNO B1 stars.
GCN 14459 table
GRB_name GRB130427A
GCN_number 14459
Detection_method Swift-BAT Det
Circular_text TITLE: GCN CIRCULAR NUMBER: 14459 SUBJECT: GRB 130427A: RATIR Optical and NIR Observations DATE: 13/04/27 13:30:44 GMT FROM: Nat Butler at Az State U Nat Butler (ASU), Alan M. Watson (UNAM), Alexander Kutyrev (GSFC), William H. Lee (UNAM), Michael G. Richer (UNAM), Chris Klein (UCB), Ori Fox (UCB) J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (UCSC), Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico Ramirez-Ruiz (UCSC), Jos A. de Diego (UNAM), Leonid Georgiev (UNAM), Jess Gonzlez (UNAM), Carlos Romn-Ziga (UNAM), Neil Gehrels (GSFC), and Harvey Moseley (GSFC) report: We observed the field of GRB 130427A (Maselli, et al., GCN 14448) with the Reionization and Transients Infrared Camera (RATIR; www.ratir.org) on the 1.5m Harold Johnson Telescope at the Observatorio Astronmico Nacional on Sierra San Pedro Mrtir from 2013/04 27.34 to 2013/04 27.39 UTC (0.25 to 1.67 hours after the BAT trigger), obtaining a total of 1.07 hours exposure in the r' and i' bands and 0.45 hours exposure in the Z, Y, J, and H bands. For a source at afterglow location reported by Elenin et al. (GCN 14450), in comparison with SDSS DR8 and 2MASS, we obtain the following detections: i' 14.46 +/- 0.01 Z 14.13 +/- 0.03 Y 14.02 +/- 0.03 J 14.05 +/- 0.02 H 13.77 +/- 0.03 These magnitudes are not corrected for Galactic extinction in the direction of the GRB. We thank the staff of the Observatorio Astronmico Nacional in San Pedro Mrtir.
GCN 14462 table
GRB_name GRB130427A
GCN_number 14462
Detection_method MAXI Det
Circular_text TITLE: GCN CIRCULAR NUMBER: 14462 SUBJECT: GRB 130427A: MAXI/GSC detection DATE: 13/04/27 15:19:38 GMT FROM: Satoshi Nakahira at JAXA/MAXI T. Kawamuro, M. Shidatsu (Kyoto U.), S. Nakahira (JAXA), H. Negoro (Nihon U.), S. Ueno, H. Tomida, M. Kimura, M. Ishikawa (JAXA), T. Mihara, M. Sugizaki, M. Serino, M. Morii, T. Yamamoto, J. Sugimoto, T. Takagi, M. Matsuoka (RIKEN), N. Kawai, R. Usui, K. Ishikawa, T. Yoshii (Tokyo Tech), A. Yoshida, T. Sakamoto, Y. Nakano (AGU), H. Tsunemi, M. Sasaki (Osaka U.), M. Nakajima, T. Onodera, K. Fukushima, K. Suzuki (Nihon U.), Y. Ueda, M. Shidatsu (Kyoto U.), Y. Ueda (Kyoto U.), Y. Tsuboi, M. Higa (Chuo U.), M. Yamauchi, K. Yoshidome, Y. Ogawa, H. Yamada (Miyazaki U.), K. Yamaoka (Nagoya U.) report on behalf of the MAXI team MAXI/GSC detected the bright GRB 130427A in the scan transit at 2013-04-27T08:42 UT, about 50 min after the trigger by Swift-BAT (Maselli et al. GCN 14448). The one-scan averaged 2-10 keV fluxes were 71 +- 19 mCrab and 23 +- 13 mCrab in the scan transits at 2013-04-27T08:42 and 2013-04-27T10:13, respectively. There were no significant excess fluxes in the previous scan transit at 07:12 UT and in the transit at 11:46 with an upper limit of 30 mCrab for each.
GCN 14463 table
GRB_name GRB130427A
GCN_number 14463
Detection_method MAXI Det
Circular_text TITLE: GCN CIRCULAR NUMBER: 14463 SUBJECT: GRB 130427A: MAXI/GSC detection DATE: 13/04/27 15:22:47 GMT FROM: Satoshi Nakahira at JAXA/MAXI T. Kawamuro, M. Shidatsu (Kyoto U.), S. Nakahira (JAXA), H. Negoro (Nihon U.), S. Ueno, H. Tomida, M. Kimura, M. Ishikawa (JAXA), T. Mihara, M. Sugizaki, M. Serino, M. Morii, T. Yamamoto, J. Sugimoto, T. Takagi, M. Matsuoka (RIKEN), N. Kawai, R. Usui, K. Ishikawa, T. Yoshii (Tokyo Tech), A. Yoshida, T. Sakamoto, Y. Nakano (AGU), H. Tsunemi, M. Sasaki (Osaka U.), M. Nakajima, T. Onodera, K. Fukushima, K. Suzuki (Nihon U.), Y. Ueda, M. Shidatsu (Kyoto U.), Y. Ueda (Kyoto U.), Y. Tsuboi, M. Higa (Chuo U.), M. Yamauchi, K. Yoshidome, Y. Ogawa, H. Yamada (Miyazaki U.), K. Yamaoka (Nagoya U.) report on behalf of the MAXI team MAXI/GSC detected the bright GRB 130427A in the scan transit at 2013-04-27T08:42 UT, about 50 min after the trigger by Swift-BAT (Maselli et al. GCN 14448). The one-scan averaged 2-10 keV fluxes were 71 +- 19 mCrab and 23 +- 13 mCrab in the scan transits at 2013-04-27T08:42 and 2013-04-27T10:13, respectively. There were no significant excess fluxes in the previous scan transit at 07:12 UT and in the transit at 11:46 with an upper limit of 30 mCrab for each.
GCN 14464 table
GRB_name GRB130427A
GCN_number 14464
Detection_method Swift-BAT Det
Circular_text TITLE: GCN CIRCULAR NUMBER: 14464 SUBJECT: GRB 130427A: Optical Observations DATE: 13/04/27 15:40:25 GMT FROM: Myungshin Im at Seoul Nat U M. Im (CEOU/SNU) on behalf of a larger collaboration We observed GRB 130427A (Maselli et al., GCN 14448) in BVRI filters using T30 telescope (0.5m) of the iTelescope network (AAO, Australia), and also are conducting follow-up imaging observations using facilities in Korea. The T30 observation started at about 4 hours after the BAT alert, and other observations starting at a similar epoch. We clearly identify the fading afterglow in T30 images, at the location reported earlier (Elenin et al. GCN 14450). Preliminary BRI magnitudes of the afterglow in one of the epochs, calibrated against a USNO B-1 star in the vicinity of the afterglow, are given below: T(mid, UT) Mag 04-27 11:42:56 I=14.86 +- 0.12 04-27 11:45:29 R=15.60 +- 0.10 04-27 11:50:29 B=16.10 +- 0.15 Follow-up observations are still ongoing.
GCN 14465 table
GRB_name GRB130427A
GCN_number 14465
Detection_method MITSuME
Circular_text TITLE: GCN CIRCULAR NUMBER: 14465 SUBJECT: GRB 130427A: MITSuME Okayama Optical Observation DATE: 13/04/27 16:22:27 GMT FROM: Daisuke Kuroda at OAO/NAOJ D. Kuroda, K. Yanagisawa, Y. Shimizu, H. Toda (OAO, NAOJ), S. Nagayama (NAOJ), M. Yoshida (Hiroshima), K. Ohta (Kyoto) and N. Kawai(Tokyo Tech) report on behalf of the MITSuME collaboration: We observed the field of GRB 130427A (Masell et al., GCNC 14448) with the optical three color (g', Rc and Ic) CCD camera attached to the MITSuME 50cm telescope of Okayama Astrophysical Observatory. The observation started on 013-04-27 10:57:02 UT (~3.2 h after the burst). We detected the previously reported afterglow (Elenin et al., GCNC 14450) in all the three bands. Photometric results of the OT are listed below. We used SDSS catalog for flux calibration. #T0+[day] MID-UT T-EXP[sec] g' g'_err Rc Rc_err Ic Ic_err ----------------------------------------------------------------------- 0.13478 11:02:01 540.0 15.82 0.03 15.48 0.02 15.04 0.03 0.30675 15:09:39 540.0 16.45 0.06 16.27 0.03 15.87 0.04 ------------------------------------------------------------------------ T0+ : Elapsed time after the burst [day] T-EXP: Total Exposure time [sec]
GCN 14466 table
GRB_name GRB130427A
GCN_number 14466
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 14466 SUBJECT: GRB 130427A: GMG optical observation DATE: 13/04/27 17:32:43 GMT FROM: Xiao-hong Zhao at Yunnan Obs X.-H. Zhao (YNAO and PSU), J. Mao (RIKEN and YNAO), Y. X. Xin(YNAO), J.-M. Bai (YNAO) report on behalf of a larger collaboration: We observed the field of GRB 130427A (Maselli et al., GCN 14448) with 2.4m Gao-Mei-Gu (GMG) telescope. Observation was started at 13:25:18 UT on 2013-04-27 (i.e., 5.6 hrs after the burst) under a bad weather condition. The sloan filters of g', r',i' and z' were used. The afterglow is very bright in every band with magnitudes of g'~16.36, r'~16.1, i'~15.9 and z'~15.8. The observations are ongoing. We thank the GMG staff, especially Hong-Yan Gao and Jian-Duo He for performing these observations.
GCN 14468 table
GRB_name GRB130427A
GCN_number 14468
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 14468 SUBJECT: GRB 130427A: Zadko observatory - Gingin optical observations DATE: 13/04/27 17:43:48 GMT FROM: Alain Klotz at IRAP-CNRS-OMP B. Gendre, A. Klotz (IRAP-CNRS-OMP), D. Macpherson (UWA/ICRAR), D. Coward (UWA), M. Boer, K. Siellez, H. Dereli , O. Bardho (UNS-CNRS-ARTEMIS-OCA), A. Williams (PO-UWA), R. Martin (PO-UWA) report: We imaged the field of GRB 130427A detected by SWIFT (trigger 554620) with the Zadko robotic telescope (D=100cm) located at the observatory - Gingin, Australia. The observations started 3.44h after the GRB trigger (the event occured during the local afternoon). The elevation of the field increased from 23 degrees above horizon and weather conditions were good. We detect the optical couterpart discovered by Elenin et al. (GCNC 14450). The unfiltered images are analyzed regarding the R magnitude of star catalogues. The preliminary light curve is: Tstart Tstop Rmag 1sig (mins) (mins) 207 219 15.50 0.1 220 232 15.54 0.1 238 250 15.37 0.1 252 264 15.56 0.1 265 277 15.51 0.1 304 319 15.58 0.1 447 450 16.27 0.2 Magnitudes are not corrected for galactic dust extinction. This message may be cited.
GCN 14470 table
GRB_name GRB130427A
GCN_number 14470
Detection_method Swift-BAT Det
ra 173.1500°
decl 27.7060°
Circular_text TITLE: GCN CIRCULAR NUMBER: 14470 SUBJECT: GRB 130427A: Swift-BAT refined analysis DATE: 13/04/27 19:33:00 GMT FROM: Scott Barthelmy at NASA/GSFC S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC), E. E. Fenimore (LANL), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), A. Y. Lien (NASA/GSFC/ORAU), C. B. Markwardt (GSFC), A. Maselli (INAF-IASFPA), D. M. Palmer (LANL), T. Sakamoto (AGU), G. Sato (ISAS), M. Stamatikos (OSU), J. Tueller (GSFC), T. N. Ukwatta (MSU) (i.e. the Swift-BAT team): Using the data set from T-60 to T+243 sec from recent telemetry downlinks, we report further analysis of BAT GRB 130427A (trigger #554620) (Maselli, et al., GCN Circ. 14448). The BAT ground-calculated position is RA, Dec = 173.150, 27.706 deg which is RA(J2000) = 11h 32m 36.1s Dec(J2000) = +27d 42' 20.3" with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 14%. The mask-weighted light curve shows the main emission occuring during a pre-planned slew. The burst location came into the BAT FoV at ~T-52 sec. The first recorded peak started at ~T-51 sec and ending at ~T-50 sec. The main, large peak started at ~T-50 sec, peaked at ~T-42 sec (~310 cnts/cm2/sec), and ended at ~T-10 sec. The spacecraft settled at T+0, and then BAT triggered (a 64-sec image trigger) at the beginning a long slow peak starting at ~T+0 sec, peaking at ~T+90 sec, and returning to baseline ~T+2000 sec. T90 (15-350 keV) is 162.83 +- 1.36 sec (estimated error including systematics). We note that (a) there is a possibility that there was emission from this burst before it came into the BAT FoV at ~T-52 sec, and (b) that Fermi-GBM triggered on this burst at 07:47:06.42 (T_bat-51 sec) [GCN/FERMI_GBM_FLIGHT_POSITION Notice, TrigNum=388741629]. The time-averaged spectrum from T-51.05 to T+223.50 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.21 +- 0.02. The fluence in the 15-150 keV band is 3.1 +- 0.03 x 10^-4 erg/cm2. The 1-sec peak photon flux measured from T-44.25 sec in the 15-150 keV band is 331.0 +- 4.6 ph/cm2/sec. All the quoted errors are at the 90% confidence level. The results of the batgrbproduct analysis are available at http://gcn.gsfc.nasa.gov/notices_s/554620/BA/
GCN 14471 table
GRB_name GRB130427A
GCN_number 14471
Detection_method Fermi LAT Det
t_trigger 7:47:06 UTC
Circular_text TITLE: GCN CIRCULAR NUMBER: 14471 SUBJECT: GRB 130427A: Fermi-LAT detection of a burst DATE: 13/04/27 20:10:41 GMT FROM: Judith Racusin at GSFC S. Zhu, J. Racusin, D. Kocevski, J. McEnery (NASA/GSFC), F. Longo (Univ of Trieste and INFN), J. Chiang (SLAC), G. Vianello (Stanford) report on behalf of the Fermi-LAT team: At 07:47:06 UT on 27 April 2013, Fermi LAT detected high energy emission from GRB 130427A, which was also detected by Fermi-GBM (trigger 388741629/130427324) and by Swift (Maselli et al. GCN 14448). The GBM detection triggered an autonomous repoint of the spacecraft. The LAT on-ground location is consistent with the optical position reported in Elenin et al. (GCN 14450). The burst was about 47 deg from the LAT boresight at the time of the trigger and within the LAT field of view for the next 700 seconds. The data from the Fermi LAT show a multi-peaked light curve consistent with the GBM trigger. More than 200 photons above 100 MeV are observed within 100 seconds with a TS of >1000. Using the non-standard LAT Low Energy (LLE) data selection, thousands of counts above background were detected within a 100 s interval coinciding with the time of the GBM emission, with a significance of ~40 sigma. The highest energy LAT photon has an energy of 94 GeV. A GBM circular is forthcoming. The Fermi LAT point of contact for this burst is Sylvia Zhu (s.jc.zhu@gmail.com). The Fermi LAT is a pair conversion telescope designed to cover the energy band from 20 MeV to greater than 300 GeV. It is the product of an international collaboration between NASA and DOE in the U.S. and many scientific institutions across France, Italy, Japan and Sweden. [GCN OPS NOTE(30apr13): Per author's request, time in the first sentence was changed from "07:47:15" to "07:47:06".]
GCN 14472 table
GRB_name GRB130427A
GCN_number 14472
Detection_method Swift-UVOT Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 14472 SUBJECT: GRB130427A: Swift/UVOT followup observations of an Optical Afterglow DATE: 13/04/27 20:22:45 GMT FROM: Tyler Pritchard at PSU T. Pritchard (PSU), A. Maselli (INAF-IASFPA), N. P. M. Kuin (MSSL), S. R. Oates (MSSL-UCL), M. De Pasquale (MSSL-UCL), and M. H. Siegel (PSU), report on behalf of the Swift/UVOT team: Further to Maselli et al., GCN Circ. 14448 we have performed manual stacking and aspect corrections on the initial UVOT image. These resulting images still retain some instrumental effects due to the brightness of the object and loss of star tracking lock. Preliminary 3-sigma detections using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the UVOT observations are: Filter T_start(s) T_stop(s) Exp(s) Mag wh 1522 1542 19.5 13.81.1 v 382 401 19.5 12.10.04 b 480 500 19.5 12.61.09 u 456 475 19.5 11.81.09 w1 430 450 19.5 11.20.04 m2 406 426 19.5 11.20.04 w2 358 377 19.5 11.20.04 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.24 in the direction of the burst (Schlegel et al. 1998).
GCN 14473 table
GRB_name GRB130427A
GCN_number 14473
Detection_method Fermi GBM Det
t_trigger 7:47:06.420 UTC
Circular_text TITLE: GCN CIRCULAR NUMBER: 14473 SUBJECT: GRB 130427A: Fermi GBM observation DATE: 13/04/27 20:27:19 GMT FROM: Andreas von Kienlin at MPE A. von Kienlin (MPE) reports on behalf of the Fermi GBM Team: "At 07:47:06.42 UT on 27 April 2013, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 130427A (trigger 388741629/130427324) which was also detected by the Swift/BAT and Fermi/LAT (Maselli et al. 2013, GCN 14448 and S. Zhu et al., GCN 14471) The GBM on-ground location is consistent with the Swift position. The angle from the Fermi LAT boresight is 48 degrees. Based on hard and intense emission in a GBM BGO detector, GBM initiated an Autonomous Report Request. This request caused Fermi to reorient towards this GRB (GBM flight location). The GBM light curve consists of a bright structured peak followed at ~T0+120 s by a FRED-like pulse. The overall duration (T90) is about 138s s (50-300 keV). Owing to the brightness of the burst, systematic effects are very large and no single model gives an adequate fit in this preliminary analysis. A Band function fit in the interval from T0+0.002 s to T0+18.432 s yields the following parameters Epeak = 830 +/- 5 keV, alpha = -0.789 +/- 0.003, and beta = -3.06 +/- 0.02. The event fluence (10-1000 keV) in this time interval is (1.975 +/- 0.003)E-03 erg/cm^2. The 1.024 sec peak photon flux measured starting from T0+7.48808 s in the 8-1000 keV band is 1052 +/- 2 ph/s/cm^2, making this the most intense and fluent GRB detected by Fermi GBM. Further analysis is being performed"
GCN 14474 table
GRB_name GRB130427A
GCN_number 14474
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 14474 SUBJECT: GRB 130427A: optical observations in CrAO DATE: 13/04/27 21:13:31 GMT FROM: Alexei Pozanenko at IKI, Moscow A. Volnova ( IKI), D. Shakhovskoy (CrAO), V. Rumyantsev (CrAO), A. Pozanenko (IKI) report on behalf of larger GRB follow-up collaboration: We started observation of the field of the Swift GRB 130427A (Maselli et al., GCN 14448) with AZT-11 telescope of CrAO observatory on Apr. 27 (UT) 18:21:45 in VRI filters. We clearly detect still bright optical counterpart of GRB 130427A (Maselli et al., GCN 14448, Elenin et al. GCN 14450, Perley GCN 14451). Preliminary photometry is following filter tstart (UT) exp,s T-t0,d OT +/- err R 18:21:45 120 0,76580 16,71 +/- 0,06 R 18:27:52 120 0,77005 16,87 +/- 0,06 R 18:34:00 120 0,77431 16,83 +/- 0,07 R 18:40:07 120 0,77855 16,81 +/- 0,06 Observation is continuing.
GCN 14475 table
GRB_name GRB130427A
GCN_number 14475
Detection_method Swift Other
ra 173.1301°
decl 27.7064°
Circular_text TITLE: GCN CIRCULAR NUMBER: 14475 SUBJECT: GRB 130427A: T100 observations DATE: 13/04/27 22:39:19 GMT FROM: Eda Sonbas at NASA/GSFC E. Sonbas (Adiyaman Univ.), T. Guver (Sabanci Univ.), E. Gogus (Sabanci Univ.), H. Kirbiyik (TUG) report on behalf of a larger collaboration We observed the field of Swift GRB 130427A (Maselli et al. GCN#14448) with the 1.0 meter T100 telescope (TUBITAK National Observatory, Antalya - Turkey), starting April, 27, 20:39:28 UT (~ 13 hours after the trigger). Observations were carried out in the R filter under good weather conditions. The afterglow is clearly detected in 60 s R band images at a position that is consistent with Elenin et al. GCN#14450 Using USNO-B1 star USNO-B1 1177-0254824 (RA= 11:32:31.23, Dec= +27:42:23.02 ) in the field, the magnitudes of the OT were estimated as follows; t-t0 (hr) exp.(s) filt mag err (+/-) 12.850 60 R 16.2 0.05 12.871 60 R 16.6 0.03 12.874 60 R 16.3 0.03 12.877 60 R 16.5 0.01 Further observations using the same filter are ongoing. We are grateful to the TUBITAK National Observatory staff for promptly scheduling the observations and their technical support.
GCN 14476 table
GRB_name GRB130427A
GCN_number 14476
Detection_method Swift Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 14476 SUBJECT: GRB 130427A: RAPTOR Bright Counterpart Before Swift Trigger DATE: 13/04/28 00:12:42 GMT FROM: James Wren at LANL J. Wren, W.T. Vestrand, P. Wozniak, and H. Davis, of Los Alamos National Laboratory report: Three RAPTOR full-sky persistent monitors at Maui, HI, and Los Alamos, NM, independently detected bright optical emission at the location of the Swift trigger 554620 (Maselli, et al., GCN 14448). Starting at 07:47:07.28 UT (50.2 seconds before the Swift trigger) we detect a brightening counterpart which peaks at magnitude R~7.4. After the peak, the source fades to below 10th magnitude at approximately the Swift trigger time. The unfiltered images from all three monitors are calibrated to the Tycho-2 V-band catalog.
GCN 14478 table
GRB_name GRB130427A
GCN_number 14478
Detection_method Optical
redshift 0.3380
Circular_text TITLE: GCN CIRCULAR NUMBER: 14478 SUBJECT: GRB 130427A: NOT optical photometry and redshift DATE: 13/04/28 00:47:29 GMT FROM: Dong Xu at DARK/NBI D. Xu (DARK/NBI), A. de Ugarte Postigo (IAA-CSIC, DARK/NBI), S. Schulze (PUC and MCSS), J. Jessen-Hansen (AU), G. Leloudas (OKC, Stockholm), T. Kruehler, J.P.U. Fynbo (DARK/NBI), P. Jakobsson (U. Iceland) report on behalf of a larger collaboration: We observed the field of GRB 130427A (Maselli et al., GCN 14448) with the 2.5m Nordic Optical Telescope (NOT) equipped with the ALFOSC camera. Observations started at 20:39:12 UT on 2013-04-27 (i.e., 12.85 hr after the BAT trigger). We first obtained a series of frames in the sloan u-, g-, r-, i-, and z-band filters. The optical afterglow (ref., Elenin et al., GCN 14450) is clearly detected in the stacked images in each of these filters. Preliminary analysis gives the following magnitudes u=17.70+/-0.03 g=17.34+/-0.03 r=17.07+/-0.03 i=16.94+/-0.03 z=16.88+/-0.03 at a mean time of 12.96 hr post-trigger, calibrated with nearby stars in the SDSS field. We also carried out a 1800s spectroscopic exposure. The spectrum covers 3200 - 9100 AA at a resolution of ~700 and has a high S/N. We detect prominent absorption lines of the MgII doublet, MgI and CaII K & H as well as weak emission lines of the [OII] doublet and H-beta, all at a common redshift of z=0.338+/-0.002, consistent with the redshift reported by Levan et al. (GCN 14455).
GCN 14480 table
GRB_name GRB130427A
GCN_number 14480
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 14480 SUBJECT: GRB 130427A: VLA 5 GHz detection DATE: 13/04/28 03:38:35 GMT FROM: Ashley Zauderer at CfA B. A. Zauderer, E. Berger, S. Chakraborti, and A. Soderberg (Harvard) report on behalf of a larger collaboration: "We observed the position of GRB 130427A (Maselli et al.; GCN 14448) beginning 2013 Apr 27.99 (dt = 0.67 d) with the Very Large Array in its D configuration (synthesized beam ~18'' x 11''). At a mean frequency of ~5.8 GHz, we detect a source with a flux of ~1 mJy +/- 20 uJy at a position consistent with the optical afterglow (e.g. Elenin et al., Perley et al.; GCNs 14450, 14451). Followup observations are planned for this nearby z~0.34 GRB (Levan et al., Xu et al; GCNs 14455, 14478). We thank the VLA observatory staff for their support of these observations."
GCN 14481 table
GRB_name GRB130427A
GCN_number 14481
Detection_method Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 14481 SUBJECT: GRB 130427A: SNUO/SOAO/BOAO Observation DATE: 13/04/28 03:47:29 GMT FROM: Myungshin Im at Seoul Nat U M. Im, C. Choi (CEOU/SNU), H.-I. Sung, Y.-B. Jeon (KASI), and Y. Urata (NCU) on behalf of a larger collaboration We continued our follow-up imaging observation of GRB 130427A (Maselli et al., GCN 14448) in BVRI filters at Seoul National University Observatory (SNUO, 0.6m), Sobaeksan Optical Astoronomy Observatory (SOAO, 0.6m), and Bohyunsan Optical Astronomy Observatory (BOAO), all located in Korea. The observations span the time period of about 4 hrs between 04-27 11:28 and 04-27 15:48 UT. The GRB afterglow (e.g., Elenin et al. GCN 14450; Im GCN 14464) is identified in the observed frames at magnitudes of ~16-17 mag Further analysis of the data is ongoing, and additional follow-up observation with these and other facilities is ongoing and planned. We thank the staffs of SOAO for performing the ToO observation.
GCN 14482 table
GRB_name GRB130427A
GCN_number 14482
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 14482 SUBJECT: GRB 130427A: CARMA 85 GHz detection DATE: 13/04/28 05:22:11 GMT FROM: Ashley Zauderer at CfA B. A. Zauderer, E. Berger, S. Chakraborti, and A. M. Soderberg (Harvard) report on behalf of the CARMA Key Project "A Millimeter View of the Transient Universe": "We began observing the field of GRB 130427A (Maselli et al.; GCN 14448) with the Combined Array for Research in Millimeter Astronomy on 2013 Apr 28.13 UT (dt ~ 0.8 d). In 45 minutes integration on source at a mean frequency of 85 GHz, we detect a radio counterpart with a preliminary flux of ~3 mJy (>10-sigma) at a position consistent with the reported optical afterglow (Elenin et al., Perley et al.; GCNs 14450, 14451) and our VLA 5 GHz detection (Zauderer et al.; GCN 14480). Observations are ongoing. We thank the CARMA observers and the observatory staff for their support."
GCN 14483 table
GRB_name GRB130427A
GCN_number 14483
Detection_method Swift-BAT Det
Circular_text TITLE: GCN CIRCULAR NUMBER: 14483 SUBJECT: GRB 130427A: Continued RATIR Optical and NIR Observations DATE: 13/04/28 05:46:39 GMT FROM: Nat Butler at Az State U Nat Butler (ASU), Alan M. Watson (UNAM), Alexander Kutyrev (GSFC), William H. Lee (UNAM), Michael G. Richer (UNAM), Chris Klein (UCB), Ori Fox (UCB) J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (UCSC), Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico Ramirez-Ruiz (UCSC), Jos A. de Diego (UNAM), Leonid Georgiev (UNAM), Jess Gonzlez (UNAM), Carlos Romn-Ziga (UNAM), Neil Gehrels (GSFC), and Harvey Moseley (GSFC) report: We again observed the field of GRB 130427A (Maselli, et al., GCN 14448) with the Reionization and Transients Infrared Camera (RATIR; www.ratir.org) on the 1.5m Harold Johnson Telescope at the Observatorio Astronmico Nacional on Sierra San Pedro Mrtir from 2013/04 28.14 to 2013/04 28.20 UTC (19.62 to 20.99 hours after the BAT trigger), obtaining a total of 1.07 hours exposure in the r' and i' bands and 0.45 hours exposure in the Z, Y, J, and H bands. We continue to detect the optical/NIR afterglow (Elenin et al; GCN 14450) in all bands. In comparison with SDSS DR8 and 2MASS, we find: r' 17.68 +/- 0.01 i' 17.52 +/- 0.01 Z 17.26 +/- 0.04 Y 17.12 +/- 0.02 J 17.21 +/- 0.02 H 17.01 +/- 0.03 These magnitudes are in the AB system and not corrected for Galactic extinction in the direction of the GRB. Uncertaints are 1-sigma. The source has faded by about 3 magnitudes in all bands as compared to our measurements last night (Butler et al. 2013; GCN 14459). We thank the staff of the Observatorio Astronmico Nacional in San Pedro Mrtir.
GCN 14484 table
GRB_name GRB130427A
GCN_number 14484
Detection_method INTEGRAL
Circular_text TITLE: GCN CIRCULAR NUMBER: 14484 SUBJECT: GRB 130427A: SPI-ACS/INTEGRAL observations DATE: 13/04/28 06:38:27 GMT FROM: Alexei Pozanenko at IKI, Moscow A. Pozanenko (IKI), P. Minaev (IKI), A. Volnova (IKI) report: The SPI-ACS detector (> 80 keV) of INTEGRAL observatory was triggered by the Swift GRB 130427A (Maselli et al., GCN 14448) on (UT) T0=07:47:06.36. Light curve of the GRB 130427A (http://www.isdc.unige.ch/integral/ibas/cgi-bin/ibas_acs_web.cgi) consists of the first peak of ~ 1 s duration which coincides with bright optical emission detected by RAPTOR (Wren et al., GCN 14476). This peak is also clearly visible in the BAT light curve at ~T0_BAT-51 s ( http://gcn.gsfc.nasa.gov/notices_s/554620/BA/ ). Following the first peak extremely intense emission was detected coinciding with BAT/Swift and Fermi-LAT detection (Zhu et al., GCN 14471). The emission in SPI-ACS detector is significantly detectable at least up to 100 s after T0. The SPI-ACS light curve can be also found at http://grb.rssi.ru/GRB130427A/GRB130427A_SPI-ACS.png
GCN 14485 table
GRB_name GRB130427A
GCN_number 14485
Detection_method Swift-XRT Other
ra 173.1359°
decl 27.6977°
redshift 0.3400
Circular_text TITLE: GCN CIRCULAR NUMBER: 14485 SUBJECT: GRB 130427A: Swift-XRT refined Analysis DATE: 13/04/28 08:29:05 GMT FROM: Phil Evans at U of Leicester J.A. Kennea (PSU), M.C. Stroh (PSU), D.N. Burrows (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), C. Pagani (U. Leicester), A. Melandri (INAF-OAB), B. Sbarufatti (INAF-OAB/PSU), G. Stratta (ASDC) and A. Maselli report on behalf of the Swift-XRT team: We have analysed 2.4 ks of XRT data for GRB 130427A (Maselli et al. GCN Circ. 14448), from 130 s to 48.1 ks after the BAT trigger. The data comprise 84 s in Windowed Timing (WT) mode (the first 9 s were taken while Swift was slewing) with the remainder in Photon Counting (PC) mode. The refined XRT position is RA, Dec = 173.13594, +27.69769 which is equivalent to: RA (J2000): 11 32 32.63 Dec(J2000): +27 41 51.7 with an uncertainty of 3.5 arcsec (radius, 90% confidence). The light curve can be modelled with an initial power-law decay with an index of alpha=7.9980 (+0.0021, -1.0800), followed by a break at T+252 s to an alpha of 0.61 (+/-0.10). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.79 (+0.17, -0.16). The best-fitting absorption column is 9.9 (+6.4, -6.0) x 10^20 cm^-2, at a redshift of 0.34, in addition to the Galactic value of 1.8 x 10^20 cm^-2 (Kalberla et al. 2005). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 4.0 x 10^-11 (4.7 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Galactic foreground: 1.8 x 10^20 cm^-2 Intrinsic column: 9.9 (+6.4, -6.0) x 10^20 cm^-2 at z=0.34 Photon index: 1.79 (+0.17, -0.16) If the light curve continues to decay with a power-law decay index of 0.61, the count rate at T+24 hours will be 2.3 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 9.4 x 10^-11 (1.1 x 10^-10) erg cm^-2 s^-1. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00554620. This circular is an official product of the Swift-XRT team.
GCN 14486 table
GRB_name GRB130427A
GCN_number 14486
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 14486 SUBJECT: GRB 130427A: Kanata/HOWPol optical imaging polarimetry DATE: 13/04/28 10:21:20 GMT FROM: Koji Kawabata at HASC,Hiroshima U R. Itoh, K. Kawaguchi, Y. Moritani, K. Takaki, K. S. Kawabata, M. Ohno, H. Takahashi, Y. Tanaka, and M. Yoshida (Hiroshima Univ.) report on behalf of Kanata team: We performed a series of optical imaging polarimetry for the optical afterglow of GRB 130427A (Elenin et al., GCN 14450) from 3.87 hr through 10.04 hr after the Swift/BAT trigger (Maselli et al., GCN 14448) with HOWPol attached to the 1.5-m Kanata telescope at Higashi-Hiroshima Observatory, Japan. Our quick-look analysis indicates that the R-band magnitude of the optical afterglow was 15.9 at the beginning of our observation, and then smoothly declined. Its decline rate between 3.87 hr and 10.04 hr can be approximated by a single power-low decay with an index -1.0. The polarization seems not so large (<~3%) in that period. Further analysis is ongoing.
GCN 14487 table
GRB_name GRB130427A
GCN_number 14487
Detection_method Konus-Wind Det
t_trigger 7:47:09.501 UTC
Circular_text TITLE: GCN CIRCULAR NUMBER: 14487 SUBJECT: Konus-Wind observation of GRB 130427A DATE: 13/04/28 10:22:50 GMT FROM: Dmitry Frederiks at Ioffe Institute S. Golenetskii, R.Aptekar, D. Frederiks, E. Mazets, V. Pal'shin, P. Oleynik, M. Ulanov, D. Svinkin, and T. Cline on behalf of the Konus-Wind team, report: The long extremely intense GRB 130427A (Swift-BAT trigger #554620: Maselli et al., GCN 14448; Barthelmy et al., GCN 14470; Fermi-LAT detection: Zhu et al., GCN 14471; Fermi-GBM observation: von Kienlin, GCN 14473; SPI-ACS/INTEGRAL observations: Pozanenko et al., GCN 14484) triggered Konus-Wind (K-W) at T0=28029.501s UT (07:47:09.501) ~50 s before the BAT trigger. The K-W light curve shows a huge mult-peaked emission complex started at ~T0, peaked at ~T0+8 s, and having a duration of ~20 s. The emission is seen up to ~12 Mev. This extremely bright phase of the event passes into a weaker decaying tail out to ~T0+120s, when the second emission episode started. It shows a FRED-like pulse, ~100 times weaker in a peak count rate than the initial complex. The decaying emission is detectable by K-W in the 20-1200 keV band out to ~T0+250s, when the instrument switched into the data readout mode. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB130427_T28029/ As observed by Konus-Wind, the main phase of the burst had a fluence of (2.68 0.01)x10^-3 erg/cm2 and a 16-ms peak flux, measured from T0+7.774 s, of (6.9 0.1)x10^-4 erg/cm2/s (both in the 20 - 1200 keV energy range). The fluence of GRB 130427A is the highest observed by K-W for ~18 years of GRB observations and its peak flux is only ~30% lower than measured by K-W for the ultra-luminous GRB 110918A. The time-averaged spectrum of the main phase of the burst (measured from T0 to T0+18.688 s) is best fit in the 20 keV-15 MeV range by the GRB (Band) function with the following model parameters: the low-energy photon index alpha = -0.958 0.006, the high energy photon index beta = -4.17 0.16, the peak energy Ep = 1028 8 keV, chi2 = 124/96 dof. The spectrum at the maximum count rate (measured from T0+7.680 to T0+7.936 s) is best fit in the 20 keV - 15 MeV range by a power law with exponential cutoff model, for which: the photon index alpha = -0.57 0.02, and the peak energy Ep = 1213 31 keV, chi2 = 63/84 dof. Modelling the 3-channel time-averaged spectrum of the second emission episode (from T0+120 s to T0+250 s) by a power law with exponential cutoff model yiels the photon index alpha~-1.6 and the peak energy Ep ~ 240 keV. The 20-1200 keV energy fluence measured at this phase of the event is ~9x10^-5 erg/cm2. Assuming z=0.34 (Levan et al., GCN 14455; Xu et al. GCN 14478) and a standard cosmology model with H_0 = 70 km/s/Mpc, Omega_M = 0.27, and Omega_Lambda = 0.73, the isotropic energy release E_iso is ~8.5x10^53 erg, and the peak luminosity (L_iso)_max is ~2.7x10^53 erg/s. All the quoted errors are estimated at the 1 sigma confidence level.
GCN 14488 table
GRB_name GRB130427A
GCN_number 14488
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 14488 SUBJECT: GRB 130427A: Continued iTelescope T21 optical observations DATE: 13/04/28 11:37:46 GMT FROM: Veli-Pekka Hentunen at Taurus Hill Obs,A95 Veli-Pekka Hentunen, Markku Nissinen and Tuomo Salmi (Taurus Hill Observatory, Varkaus, Finland) report: We have continued observing GRB 130427A optical afterglow at iTelescope observatory T21 (Mayhill, New Mexico) 0.43-m/6.8 astrograph and FLI-PL6303E CCD. Two unfiltered, two photometric R filter and two photometric V filter images with 600 sec exposure time were made. The following magnitudes were obtained from the observations using NOMAD1 1176-0248446 (R=13.520, V=13.120) as the comparison: Tmid(h)+T0 Filter Exp. time Mag Mag err. 22.67 V 600 17.73V 0.11 22.85 V 600 17.72V 0.11 23.10 unfiltered 600 18.01CR 0.07 23.27 unfiltered 600 18.22CR 0.09 23.56 R 600 18.18R 0.12 23.74 R 600 18.36R 0.14
GCN 14489 table
GRB_name GRB130427A
GCN_number 14489
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 14489 SUBJECT: GRB 130427A, Optical Observations DATE: 13/04/28 11:48:15 GMT FROM: Shashi Bhushan Pandey at ROTSE S. B. Pandey and Brajesh Kumar (ARIES Nainital India, on behalf of larger Indian GRB collaboration) We observed Swift GRB 130427A field (Maselli et al., GCN 14448) using 1.04m telescope at ARIES Nainital on 2013-04-27 starting at 14:25:16 UT in UBV(RI)_c filters. Several frames were obtained in average sky conditions. We clearly detect the bright optical counterpart of GRB 130427A (Maselli et al. GCN 14448, Elenin et al. GCN 14450) in each individual exposures. The preliminary photometry is as following: (UT)Start filter exp(sec) mag 14:25:16 B 300 16.61 +/- 0.06 14:53:36 I 200 14.83 +/- 0.05 The photometry was performed in comparison to nearby USNO- B1 stars. Our observations seem to follow the power-law decay exponent ~ -0.9 as noticed by Perley and Cenko GCN 14456. Further observations are going on. This massage may be cited.
GCN 14490 table
GRB_name GRB130427A
GCN_number 14490
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 14490 SUBJECT: GRB 130427A optical time series DATE: 13/04/28 13:46:40 GMT FROM: AAVSO GRB Network at AAVSO Patrick Wiggins (Stansbury Park, Utah, United States) reports the following optical observations of the error box of GRB 130427A (GCN Circ #14448, Maselli et al.) to the AAVSO International High Energy Network: P. Wiggins reports three hours of time-series photometry of the bright GRB 130427A (Maselli et al., GCN Circ. #14448; Elenin et al., GCN Circ. # 14450). Wiggins used a 0.35-m C-14 f/5.5 telescope with an SBIG ST-10XME camera and clear filter located in Stansbury Park, Utah. Observations commenced 2013 April 27 08:05:12 UT -- less than 20 minutes post trigger -- and continued through 11:10:06 UT. The first four observations were made with 60-second exposure times, which were found to be close to saturation; subsequent exposure times were 30 seconds. The transient was detected by visual inspection of the first frame, and found to be very bright. Time-series observations were begun immediately. Thirty-three images of the field were taken, and the resulting light curve is as follows. All magnitudes are taken with respect to the comparison star GSC 01984-00021, which has an r-magnitude of 12.553 (APASS DR7, http://www.aavso.org/apass ); the resulting magnitudes should be interpreted as through a clear filter with r'-band zero point. Note that the first four magnitudes with integration times of 60 seconds may be saturated. All times are given as the mid-point of the exposure, UT on 2013 April 27, and T(0)+h is hours since trigger (07:47:57 UT): Obs. UT T(0)+h Exp. time magn. mag.err. 08:05:41.529 0.296 60.00 13.108 0.006 08:06:57.779 0.317 60.00 13.194 0.007 08:14:16.467 0.439 60.00 13.557 0.009 08:27:07.951 0.653 60.00 13.995 0.013 08:40:35.701 0.877 30.00 14.304 0.024 08:46:36.857 0.978 30.00 14.413 0.027 08:50:51.998 1.049 30.00 14.47 0.029 08:55:17.311 1.122 30.00 14.546 0.030 09:00:52.545 1.215 30.00 14.623 0.033 09:06:26.014 1.308 30.00 14.684 0.035 09:11:59.514 1.401 30.00 14.731 0.038 09:17:33.139 1.493 30.00 14.792 0.041 09:23:06.748 1.586 30.00 14.829 0.043 09:28:40.357 1.679 30.00 14.969 0.050 09:34:18.373 1.773 30.00 14.957 0.050 09:39:51.873 1.865 30.00 14.911 0.050 09:45:25.545 1.958 30.00 15.025 0.055 09:50:59.404 2.051 30.00 15.158 0.064 09:56:32.982 2.143 30.00 15.104 0.064 10:02:06.529 2.236 30.00 15.22 0.073 10:07:40.154 2.329 30.00 15.138 0.071 10:13:13.732 2.421 30.00 15.249 0.080 10:15:01.029 2.451 30.00 15.219 0.078 10:20:47.498 2.547 30.00 15.302 0.088 10:26:21.123 2.64 30.00 15.424 0.099 10:31:54.732 2.733 30.00 15.387 0.100 10:37:28.451 2.825 30.00 15.247 0.091 10:43:02.248 2.918 30.00 15.512 0.123 10:48:35.811 3.011 30.00 15.496 0.124 10:54:09.561 3.103 30.00 15.517 0.128 10:59:43.279 3.196 30.00 15.633 0.150 11:05:19.092 3.289 30.00 15.555 0.150 11:10:20.982 3.373 30.00 15.48 0.153 The AAVSO International High Energy Network is supported through the AAVSO Endowment Fund. We thank the Charles Curry Foundation and NASA for past support.
GCN 14491 table
GRB_name GRB130427A
GCN_number 14491
Detection_method Other
redshift 0.3399
Circular_text TITLE: GCN CIRCULAR NUMBER: 14491 SUBJECT: GRB 130427A: VLT/X-shooter redshift confirmation DATE: 13/04/28 15:05:53 GMT FROM: Hector Flores at Obs.de Paris,Meudon GRB 130427A: VLT/X-shooter redshift confirmation H. Flores (Obs. de Paris), S. Covino (INAF), D. Xu, T. Kruehler, J. Fynbo, B. Milvang-Jensen(DARK/NBI), A. de Ugarte Postigo (IAA-CSIC, DARK/NBI), L. Kaper (UVA) and K. Wiersema (U. Leicester) report on behalf of the X-shooter GRB collaboration: VLT/X-shooter observed the afterglow of GRB 130427A (Maselli et al., GCN 14448; Elenin et al., GCN 14450), starting on 2013-04-28 at UT 00:23. The observation consisted of 2x600s exposures. In the spectra we detect the continuum in the complete range from 3000 to 24800 A. We find several absorption features including FeII, MnII, MgII, MgI, TiII, CaII, NaI, and emission lines such as H-alpha, H-beta, [OIII], and [OII], all at a common redshift of z=0.3399 +/- 0.0002, consistent with the measurement in Levan et al. (GCN 14455) and Xu et al. (GCN 14478). We thank the Paranal staff for excellent support, in particular Andrea Mehner and Christophe Martayan.
GCN 14492 table
GRB_name GRB130427A
GCN_number 14492
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 14492 SUBJECT: GRB 130427A : Xinglong TNT optical observation DATE: 13/04/28 17:55:49 GMT FROM: L.P. Xin at NAOC L.P. Xin, J. Y. Wei, Y. L. Qiu, J. Wang, J. S. Deng, C. Wu, X.H. Han report on behalf of EAFON team: We began to observe the field of GRB 130427A (Maselli, et al., GCN 14448) using 80cm TNT telescope located at Xinglong observatory, China at 12:52:38 UT on 2013-04-28. We obtained several B, V, R-band images. The optical counterpart is detected in all images. The prelinary analysis shows that its brightness is about R=18.3 mag, calibrated with USNO B2 stars, at the mean time of 29.08 h after the trigger time. This message may be cited.
GCN 14494 table
GRB_name GRB130427A
GCN_number 14494
Detection_method Other
ra 173.1368°
decl 27.6989°
Circular_text TITLE: GCN CIRCULAR NUMBER: 14494 SUBJECT: GRB 130427A: CARMA 3mm observations DATE: 13/04/28 22:38:23 GMT FROM: Daniel Perley at Caltech D. A. Perley (Caltech) reports on behalf of a larger collaboration: We observed the position of GRB 130427A (Maselli et al.; GCN 14448) with the Combined Array for Research in Millimeter Astronomy on two epochs on 2013-04-28 (UT), between 01:45 and 02:46 and again between 07:22 and 08:14, at a frequency of 93 GHz (3 mm). The afterglow is well-detected in both epochs. Preliminary reduction gives fluxes of: 3.7 +/- 0.4 mJy (t_mid = 0.769 day) 2.6 +/- 0.4 mJy (t_mid = 1.000 day) These values are consistent with the flux reported by Zauderer et al. (GCN 14482) as also measured by CARMA at a time intermediate between these epochs. The source location is: RA = 11:32:32.82 Dec = +27:41:56.06 (J2000, uncertainty 0.4 arcsec) Further observations are planned. We thank the CARMA staff for their support in executing these observations.
GCN 14495 table
GRB_name GRB130427A
GCN_number 14495
Detection_method Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 14495 SUBJECT: GRB 130427A: Nishi-Harima NIR Observations DATE: 13/04/29 00:11:01 GMT FROM: Daisuke Kuroda at OAO/NAOJ J. Takahashi, K. Morihana, S. Honda and Y. Takagi (Univ. of Hyogo) report on behalf of Nayuta team: We observed the field of GRB 130427A (Masell et al., GCNC 14448) in near-infared three bands (J, H and Ks) with NIC attached to the Nayuta 2-m telescope at the Nishi-Harima Astronomical Observatory. The observations were conducted from 2013-04-27 12:26 UT to 2013-04-27 17:25 UT (from ~4.7 h to ~9.6 h after the burst). We detected the previously reported afterglow (Elenin et al., GCNC 14450) in all the three bands. Photometric results of our observations are listed below. We used 2MASS 11323755+2743196 as the reference star for flux calibration. # MID-UT T-EXP[sec] J J_err H H_err Ks Ks_err ----------------------------------------------------------------------- 12:26:56 150 14.7 0.2 13.5 0.2 13.5 0.2 13:27:59 150 14.7 0.2 14.2 0.2 13.2 0.3 14:39:42 150 14.7 0.3 14.3 0.2 13.4 0.3 17:17:31 150 --* --* 14.8 0.2 14.6 0.2 17:24:52 300 15.2 0.2 14.8 0.2 14.0 0.2 ------------------------------------------------------------------------ T-EXP: Total Exposure time [sec] * Photometry was not possible because the signal from the reference star was too low.
GCN 14497 table
GRB_name GRB130427A
GCN_number 14497
Detection_method Swift-XRT Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 14497 SUBJECT: GRB 130427A: Skynet/PROMPT Observations DATE: 13/04/29 05:45:38 GMT FROM: Adam S. Trotter at UNC-Chapel Hill/PROMPT/Skynet A. Trotter, D. Reichart, J. Haislip, A. LaCluyze, T. Berger, H. T. Cromartie, R. Egger, A. Foster, N. Frank, K. Ivarsen, M. Maples, J. Moore, M. Nysewander, E. Speckhard, and J. A. Crain report: Skynet observed the Swift/XRT localization of GRB 130427A (Maselli et al., GCN 14448, Swift trigger #554620) with four 16" telescopes of the PROMPT array at CTIO, Chile, starting at 2013-04-27, 23:28 UT, and continuing until 04-28, 05:30 UT (t=15.69h-21.67h post-trigger). It took ~124 160-s exposures, simultaneously in each of the BVRI bands. We performed photometry on each exposure, calibrated to two SDSS stars in the field. We detect a fading afterglow in BVRI at the position reported by Elenin et al. (GCN 14450), which is ~50" south of the initial XRT localization. A preliminary light curve of the first night's data is at: http://skynet.unc.edu/grb/grb130427a.png Further Skynet observations are ongoing.
GCN 14498 table
GRB_name GRB130427A
GCN_number 14498
Detection_method MITSuME
Circular_text TITLE: GCN CIRCULAR NUMBER: 14498 SUBJECT: GRB 130427A: MITSuME Okayama and Ishigakijima Optical Observation after 1 day DATE: 13/04/29 06:06:15 GMT FROM: Daisuke Kuroda at OAO/NAOJ D. Kuroda, (OAO, NAOJ), H. Hanayama (IAO, NAOJ), K. Yanagisawa, Y. Shimizu, H. Toda (OAO, NAOJ), T. Miyaji J. Watanabe, (IAO, NAOJ), S.Nagayama (NAOJ), M. Yoshida (Hiroshima), K. Ohta (Kyoto) and N. Kawai(Tokyo Tech) report on behalf of the MITSuME collaboration: We observed the field of GRB 130427A (Masell et al., GCNC 14448) with the optical three color (g', Rc and Ic) CCD camera attached to the MITSuME 50cm telescope of Okayama Astrophysical Observatory and the Murikabushi 1m telescope of Ishigakijima Astronomical Observatory. We detected the previously reported afterglow (Elenin et al., GCNC 14450) in all the three bands. Photometric results of the OT are listed below. We used SDSS catalog for flux calibration. Okayama Astrophysical Observatory: The observation started on 2013-04-28 11:29:25 UT (~1.15 days after the burst). #T0+[day] MID-UT T-EXP[sec] g' g'_err Rc Rc_err Ic Ic_err ----------------------------------------------------------------------- 1.16123 11:40:06 1440.0 18.4 0.2 17.9 0.1 17.7 0.1 ------------------------------------------------------------------------ T0+ : Elapsed time after the burst [day] T-EXP: Total Exposure time [sec] Ishigakijima Astronomical Observatory: The observation started on 2013-04-28 14:02:08 UT (~1.26 days after the burst). #T0+[day] MID-UT T-EXP[sec] g' g'_err Rc Rc_err Ic Ic_err ----------------------------------------------------------------------- 1.31290 15:18:30 1020.0 18.61 0.06 18.22 0.04 17.37 0.05 ------------------------------------------------------------------------ T0+ : Elapsed time after the burst [day] T-EXP: Total Exposure time [sec]
GCN 14502 table
GRB_name GRB130427A
GCN_number 14502
Detection_method Swift-XRT Other
redshift 0.3400
Circular_text TITLE: GCN CIRCULAR NUMBER: 14502 SUBJECT: GRB 130427A: Improved Swift-XRT analysis DATE: 13/04/29 14:32:17 GMT FROM: Phil Evans at U of Leicester P.A. Evans, K.L. Page (U. Leicester), A. Maselli, V. Mangano, M. Capalbi (INAF-IASFPA), D.N. Burrows (PSU) report on behalf of the Swift-XRT team: We have reanalysed the XRT data for GRB 130427A (Maselli et al. GCN Circ. 14448) from 144 s to 141 ks after the BAT trigger. The data comprise 1.9 ks of Windowed Timing (WT) mode data, with the rest taken in Photon Counting (PC) mode. The star trackers on Swift failed to find a correct aspect solution during the first 1.9 ks of exposure (when the WT mode data were collected; see GCN Circ. 14448), and the GRB is seen to be drifting on the XRT detector. We have fitted this drift as a linear function, which is a good representation to the data. We have then rebuilt the GRB light curve and spectrum using this information. However, the time-tag of individual photon events may be incorrect by up to 1 second, and the method that we have used to correct the attitude may introduce low-level fluctuations. It is therefore inappropriate to perform any detailed timing or periodicity analysis with the current XRT data. We are working to rectify this situation. The light curve can be modelled as a broken power-law with an initial decay index of 2.81 (+/- 0.04) with a break at T+421 s to a slope of alpha=1.17 (+/-0.01). This then breaks again at T+53.4ks to a final slope of 1.79 (+0.5, -0.05). A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 1.91 (+/-0.11). The best fitting absorption column is 2.8 (+/-0.05) x 10^21 cm^-2 at a redshift of 0.34, in addition to the Galactic value of 1.8 x 10^20 cm^-2 (Kalberla et al. 2005). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.8 x 10^-11 (5.2 x 10^-11) erg cm^-2 count^-1. If the light curve continues to decay with a power-law decay index of 1.79, the count rate at T+3 days will be 0.14 count/sec, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 5.3 x 10^-12 (7.3 x 10^-12) erg cm^-2 s^-1. The automated light curve of this GRB is online at http://www.swift.ac.uk/xrt_curves/00554620/ This circular is an official product of the Swift-XRT team.
GCN 14503 table
GRB_name GRB130427A
GCN_number 14503
Detection_method Konus-Wind Det
redshift 0.3400
Circular_text TITLE: GCN CIRCULAR NUMBER: 14503 SUBJECT: GRB 130427A in the Ep,i - Eiso plane DATE: 13/04/29 17:09:35 GMT FROM: Lorenzo Amati at INAF-IASF/Bologna L. Amati (INAF - IASF Bologna, Italy), S. Dichiara, F. Frontera, C. Guidorzi (University of Ferrara, Italy), report: Based on the preliminary values of fluence and spectral parameters reported by the Fermi/GBM (Kienlin et al., GCN 14473) and Konus-Wind (Golenetskii et al., GCN 14487) teams, and by assuming a redshift of 0.34 (Levan et al., CGN 14455; Flores et al., GCN 14491) and a standard Lambda_CDM cosmology with H_0 = 70 km/s/Mpc, Omega_M = 0.27, Omega_Lambda = 0.73, we estimate for GRB 130427A an intrinsic spectral peak energy Ep,i of 1250+/-150 keV and an isotropic-equivalent radiated energy of (1.05+/-0.15)x10^54 erg (1-10000 keV cosmological rest-frame). These values are fully consistent with the best-fit power-law of the Ep,i-Eiso correlation holding for all long-bright cosmological GRBs (as determined, e.g., by Amati et al. 2009, A&A 508, 173). This is further evidence that the prompt emission properties of GRB 130427A, the most energetic GRB detected at z < 1, are the same as those of very bright, high-redshift events. Hence, its relatively low redshift makes it a unique case for investigating wether this class of events is associated to SNe with properties similar to those associated to "local" sub-luminous GRBs.
GCN 14505 table
GRB_name GRB130427A
GCN_number 14505
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 14505 SUBJECT: GRB 130427A: CrAO RT-22 36 GHz observation DATE: 13/04/29 20:35:17 GMT FROM: Alexei Pozanenko at IKI, Moscow A. Volvach (CrAO), L. Volvach (CrAO), A. Pozanenko (IKI) on behalf of larger collaboration report: We observed the field of GRB 130427A (Maselli et al., GCN 14448) on Apr. 28 between (UT) 16:22-18:41 with 22-m radio telescope RT-22 of Crimean Astrophysical Observatory at mean frequency of 36 GHz. At the position of the optical (Elenin et al., GCN 14450; Perley et al., GCN 14451) and radio afterglow (Zauderer et al., GCN 14480; Zauderer et al., GCN 14482; Perley, GCN 14494) we detected a source with a flux 1.9 ± 0.4 mJy at T_mid = 1.405 days after burst trigger.
GCN 14506 table
GRB_name GRB130427A
GCN_number 14506
Detection_method Swift-BAT Det
Circular_text TITLE: GCN CIRCULAR NUMBER: 14506 SUBJECT: GRB 130427A: Continued RATIR Optical and NIR Observations DATE: 13/04/29 20:41:58 GMT FROM: Nat Butler at Az State U Nat Butler (ASU), Alan M. Watson (UNAM), Alexander Kutyrev (GSFC), William H. Lee (UNAM), Michael G. Richer (UNAM), Chris Klein (UCB), Ori Fox (UCB) J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (UCSC), Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico Ramirez-Ruiz (UCSC), Jos A. de Diego (UNAM), Leonid Georgiev (UNAM), Jess Gonzlez (UNAM), Carlos Romn-Ziga (UNAM), Neil Gehrels (GSFC), and Harvey Moseley (GSFC) report: We again observed the field of GRB 130427A (Maselli, et al., GCN 14448) with the Reionization and Transients Infrared Camera (RATIR; www.ratir.org) on the 1.5m Harold Johnson Telescope at the Observatorio Astronmico Nacional on Sierra San Pedro Mrtir from 2013/04 29.14 to 2013/04 29.27 UTC (43.64 to 46.60 hours after the BAT trigger), obtaining a total of 3.02 hours exposure in the r' and i' bands and 1.57 hours exposure in the Z, Y, J, and H bands. We continue to detect the optical/NIR afterglow (Elenin et al; GCN 14450) in all bands. In comparison with SDSS DR8 and 2MASS, we find: r' 18.90 +/- 0.01 i' 18.67 +/- 0.01 Z 18.38 +/- 0.03 Y 18.19 +/- 0.02 J 18.29 +/- 0.02 H 18.01 +/- 0.02 These magnitudes are in the AB system and not corrected for Galactic extinction in the direction of the GRB. Uncertaints are 1-sigma. The source has faded by about 1 magnitude in all bands as compared to our measurements on the previous night (Butler et al. 2013; GCN 14483). We thank the staff of the Observatorio Astronmico Nacional in San Pedro Mrtir.
GCN 14507 table
GRB_name GRB130427A
GCN_number 14507
Detection_method correction
Circular_text TITLE: GCN CIRCULAR NUMBER: 14507 SUBJECT: GRB 130427A: SARA-N detection DATE: 13/04/29 21:18:59 GMT FROM: Dieter Hartmann at Clemson.U William C. Keel (U. of Alabama, Tuscaloosa), Dieter Hartmann and Aman Kaur (Clemson University) report: We observed the field of GRB 130427A (Maselli, et al., GCN 14448) with the SARA 0.9m telescope at KPNO (http://saraobservatory.org) from 0350-0420 UT on April 29, obtaining a total of 30 min exposure in the B,V, and R band. We detect the optical afterglow (Elenin et al; GCN14450) in all bands. In comparison with Landolt (PG 0942) standard stars we find B = 19.32 V = 19.00 R = 18.53 These magnitudes are not corrected for Galactic extinction, but include KPNO airmass corrections at the time of observation. This message may be cited
GCN 14508 table
GRB_name GRB130427A
GCN_number 14508
Detection_method Fermi LAT Other
ra 173.1480°
decl 27.7090°
Circular_text TITLE: GCN CIRCULAR NUMBER: 14508 SUBJECT: GRB 130427A: Fermi-LAT refined analysis DATE: 13/04/29 21:30:22 GMT FROM: Judith Racusin at GSFC S. Zhu, J. Racusin (NASA/GSFC), J. Chiang (SLAC), G. Vianello (Stanford) report on behalf of the Fermi LAT team: Using LAT source class events >100 MeV between T0+0 and 700 seconds after the GBM trigger, we find a LAT localization of RA = 173.148, Dec = +27.709, with a 68% containment radius of 0.068 degrees (statistical only). This localization is consistent with other reported positions. The >100 MeV emission spectrum during the GBM T90 (T0+0 to 138 seconds) is fit by a power law with an index of -1.96 +/- 0.07. The fluence during this time is (1.1 +/- 0.1)E-4 erg/cm^2, making this the highest fluence LAT-detected burst in the LAT energy range (Fermi LAT Collaboration, arXiv:1303.2908). The >100 MeV peak flux, measured from 11.52 to 37.33 seconds, is (1.4 +/- 0.2)E-3 ph/cm^2/s. The LAT Low Energy (LLE) emission during the bright structured peak (0 to 20 seconds) is roughly correlated with the GBM emission. A spike at T0+0 seconds is coincident in both LAT and LLE, but precedes the onset of the GBM emission. There are peaks in the LAT light curve at approximately 13 and 22 seconds; neither peak is coincident with the LLE or GBM. Significant emission >100 MeV was detected throughout the first orbit until ~735 seconds, at which point the burst became occulted by the Earth. The LAT emission was still significantly detected when the burst emerged from occultation at ~3000 seconds, and remained detectable for about a day. The extended emission light curve can be fit by a broken power-law that has a power-law index = -0.89 +/- 0.04 at early times, and at late times, it has an index in the range -1.3 to -1.5; the temporal break occurs around 550-800 seconds after the GBM trigger. We clarify that the Swift-BAT trigger time (Barthelmy et al., GCN 14470) is ~51 seconds after the GBM trigger, so the emission detected by RAPTOR beginning ~50 seconds before the Swift trigger with a peak magnitude of R~7.4 (Wren et al., GCN 14476) is therefore coincident with the GBM and LAT emission onset. The Fermi LAT point of contact for this burst is Sylvia Zhu (s.jc.zhu@gmail.com). The Fermi LAT is a pair conversion telescope designed to cover the energy band from 20 MeV to greater than 300 GeV. It is the product of an international collaboration between NASA and DOE in the U.S. and many scientific institutions across France, Italy, Japan and Sweden.
GCN 14509 table
GRB_name GRB130427A
GCN_number 14509
Detection_method Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 14509 SUBJECT: GRB 130427A: further GMG observations DATE: 13/04/29 22:59:58 GMT FROM: Xiao-hong Zhao at Yunnan Obs X.-H. Zhao (YNAO and PSU), J. Mao (RIKEN and YNAO), J. G. Wang(YNAO), J.-M. Bai (YNAO) report on behalf of a larger collaboration: We further observed the afterglow of GRB 130427A (Maselli et al., GCN 14448) with 2.4m Gao-Mei-Gu (GMG) telescope on Apr 28 and Apr 29. The sloan filter of r' was used. The magnitudes of the afterglow are r'~18.2 31.16 hrs after trigger r'~18.9 53.37 hrs after trigger We thank the GMG staff, especially Hong-Yan Gao, Jian-Duo He and Gui-Hua He for performing these observations.
GCN 14510 table
GRB_name GRB130427A
GCN_number 14510
Detection_method Swift-XRT Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 14510 SUBJECT: GRB 130427A: Continued Skynet/PROMPT Observations DATE: 13/04/30 01:26:11 GMT FROM: Adam S. Trotter at UNC-Chapel Hill/PROMPT/Skynet A. Trotter, D. Reichart, J. Haislip, A. LaCluyze, T. Berger, H. T. Cromartie, R. Egger, A. Foster, N. Frank, K. Ivarsen, M. Maples, J. Moore, M. Nysewander, E. Speckhard, and J. A. Crain report: Skynet continued observing the Swift/XRT localization of GRB 130427A (Maselli et al., GCN 14448, Swift trigger #554620) with four 16" telescopes of the PROMPT array at CTIO, Chile, starting at 2013-04-28, 23:06 UT, and continuing until 04-29, 3:51 UT (t=39.28h-44.03h post-trigger). It took ~110 160-s exposures, simultaneously in each of the BVRI bands. We performed photometry on each exposure, calibrated to two SDSS stars in the field. B-band photometry was performed on stacks of 3-4 images in order to provide at least 3sigma detections. A preliminary light curve of the second's data is at: http://skynet.unc.edu/grb/grb130427a_2.png A light curve of both the first and second nights' data is at: http://skynet.unc.edu/grb/grb130427a_1_2.png See Trotter et al. (GCN 14497) for a description of the first night's observations. Further Skynet observations are ongoing.
GCN 14511 table
GRB_name GRB130427A
GCN_number 14511
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 14511 SUBJECT: GRB 130427A: Challis Observatory optical observations DATE: 13/04/30 03:59:05 GMT FROM: Jay Norris at Boise State U. Jay Norris, Daryl Macomb (Boise State U.) report: We observed GRB 130427A with the Challis Observatory's 0.4-m telescope (114.33 deg W, 44.5 deg N, 2165 m elevation) on April 29, 05:58 to 06:22 UT. Using seventeen 10-second frames in the R filter acquired in a clear sky, centered at ~ 06:06 UT, 22.3 hours after the Swift/BAT trigger (GCN 14448), we clearly detected the optical afterglow. Comparison with six stars in the field of view (R = 15.5 to 16.8 mag) yielded an estimate of R = 17.6 mag for the afterglow with uncertainty of ~ 0.15 mag. Further observations were interrupted by clouds. [GCN OPS NOTE(30apr13): Per author's request, the affiliation in the FROM-line was changed to Boise State U.]
GCN 14513 table
GRB_name GRB130427A
GCN_number 14513
Detection_method MITSuME
Circular_text TITLE: GCN CIRCULAR NUMBER: 14513 SUBJECT: GRB 130427A: MITSuME Ishigakijima Optical Observation after 2 days DATE: 13/04/30 14:33:12 GMT FROM: Daisuke Kuroda at OAO/NAOJ D. Kuroda (OAO, NAOJ), H. Hanayama, T. Miyaji, J. Watanabe (IAO, NAOJ), K. Yanagisawa (OAO, NAOJ), S.Nagayama (NAOJ), M. Yoshida (Hiroshima), K. Ohta (Kyoto) and N. Kawai(Tokyo Tech) report on behalf of the MITSuME collaboration: We observed the field of GRB 130427A (Masell et al., GCNC 14448) with the optical three color (g', Rc and Ic) CCD camera attached to the Murikabushi 1m telescope of Ishigakijima Astronomical Observatory. We detected the previously reported afterglow (Elenin et al., GCNC 14450) in all the three bands. The observation started on 2013-04-29 15:02:55 UT (~2.30 days after the burst). Photometric results of the OT are listed below. We used SDSS catalog for flux calibration. #T0+[day] MID-UT T-EXP[sec] g' g'_err Rc Rc_err Ic Ic_err ----------------------------------------------------------------------- 2.31262 15:18:06 1500.0 19.19 0.05 18.87 0.04 18.65 0.09 2.33383 15:48:38 1440.0 19.29 0.06 18.90 0.05 18.76 0.11 ------------------------------------------------------------------------ T0+ : Elapsed time after the burst [day] T-EXP: Total Exposure time [sec]
GCN 14514 table
GRB_name GRB130427A
GCN_number 14514
Detection_method Swift-BAT Det
Circular_text TITLE: GCN CIRCULAR NUMBER: 14514 SUBJECT: GRB 130427A: Continued RATIR Optical and NIR Observations DATE: 13/04/30 14:42:55 GMT FROM: Nat Butler at Az State U Nat Butler (ASU), Alan M. Watson (UNAM), Alexander Kutyrev (GSFC), William H. Lee (UNAM), Michael G. Richer (UNAM), Chris Klein (UCB), Ori Fox (UCB) J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (UCSC), Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico Ramirez-Ruiz (UCSC), Jos A. de Diego (UNAM), Leonid Georgiev (UNAM), Jess Gonzlez (UNAM), Carlos Romn-Ziga (UNAM), Neil Gehrels (GSFC), and Harvey Moseley (GSFC) report: We again observed the field of GRB 130427A (Maselli, et al., GCN 14448) with the Reionization and Transients Infrared Camera (RATIR; www.ratir.org) on the 1.5m Harold Johnson Telescope at the Observatorio Astronmico Nacional on Sierra San Pedro Mrtir from 2013/04 30.14 to 2013/04 30.37 UTC (67.58 to 73.15 hours after the BAT trigger), obtaining a total of 3.91 hours exposure in the r' and i' bands and 1.64 hours exposure in the Z, Y, J, and H bands. We continue to detect the optical/NIR afterglow (Elenin et al; GCN 14450) in all bands. In comparison with SDSS DR8 and 2MASS, we find: r' 19.39 +/- 0.01 i' 19.31 +/- 0.01 Z 18.89 +/- 0.03 Y 18.75 +/- 0.03 J 18.87 +/- 0.02 H 18.56 +/- 0.03 These magnitudes are in the AB system and not corrected for Galactic extinction in the direction of the GRB. Uncertaints are 1-sigma. The source has faded by about 0.5 magnitude in all bands as compared to our measurements on the previous night (Butler et al. 2013; GCN 14506). We thank the staff of the Observatorio Astronmico Nacional in San Pedro Mrtir.
GCN 14515 table
GRB_name GRB130427A
GCN_number 14515
Detection_method Fermi LAT Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 14515 SUBJECT: GRB 130427A: high energy gamma-ray detection by AGILE DATE: 13/04/30 15:57:24 GMT FROM: Francesco Verrecchia at ASDC ========================================================================= F. Verrecchia, C. Pittori (ASDC and INAF/OAR), A. Giuliani (INAF/IASF-Mi), M. Marisaldi (INAF/IASF-Bo), F. Longo (University of Trieste and INFN Trieste), F. Lucarelli (ASDC and INAF/OAR), E. Del Monte, F. Lazzarotto, I. Donnarumma, Y. Evangelista, M. Feroci, L. Pacciani, P. Soffitta, E. Costa, I. Lapshov, M. Rapisarda (INAF/IAPS Rome), G. Barbiellini, (INFN Trieste), A. Bulgarelli, F. Gianotti, M. Trifoglio, G. Di Cocco, C. Labanti, V. Fioretti, F. Fuschino, M. Galli (INAF/IASF-Bo), A. Chen, S. Mereghetti, F. Perotti, P. Caraveo (INAF/IASF-Mi), M. Cardillo, E. Striani, M. Tavani (INAF/IAPS Rome, and Univ. Roma Tor Vergata), A. Argan, G. Piano, S. Sabatini, V. Vittorini (INAF/IAPS Rome), G. Pucella (ENEA Frascati), A. Pellizzoni, A. Trois (INAF/OA Cagliari), M. Pilia (ASTRON), S. Vercellone (INAF/IASF-Pa), P. W. Cattaneo, A. Rappoldi (INFN Pavia), A. Morselli, P. Picozza (INFN Roma-2), M. Prest, E. Vallazza (Universita' dell'Insubria), P. Lipari, D. Zanello (INFN Roma-1), P. Giommi (ASI), and G. Valentini (ASI), on behalf of the AGILE Team, report: The AGILE Gamma Ray Imaging Detector (GRID) detected high energy emission from GRB 130427A (A. Maselli et al., GCN 14448), also reported by Fermi-LAT (S. Zhu et al., GCN 14471). A preliminary analysis of the AGILE-GRID data in temporal coincidence with the GRB shows a significant excess of gamma-ray photons above 50 MeV at the location of the event. The emission detected by the AGILE-GRID mostly occurred between ~ t0 + 180 sec and t0 + 700 sec where t0 is 27 April 2013 at 07:47:15 UT. During this interval, the burst position was inside the instrument FOV. A maximum likelihood analysis of the AGILE-GRID data integrating over 12 hours, from 2013-04-27 05:00 UT to 2013-04-27 17:00 UT, using the standard parameters used by AGILE quick look to detect persistent gamma-ray sources, yields a detection at a significance level larger than 6 sigma, and a mean flux F = (8.0+/-2.7) 10-6 ph/cm2/s (E > 100 MeV). The preliminary photon spectral index obtained with this integration is 1.55 +/- 0.30. Due to the exceptionally high fluence above 100 MeV of this burst, it is possible for the first time to derive its properties using the maximum likelihood techniques routinely used in the standard data analysis of AGILE-GRID point sources. The GRB also triggered the AGILE Minicalorimeter (MCAL), sensitive to gamma-rays above 350 keV, at the time 07:47:06 UT. According to the MCAL light curve, the emission lasts for about 20 s divided into three main episodes. Although the large initial off-axis angle (more than 120 degrees) prevents an accurate spectral analysis of MCAL data, significant emission above 15 MeV is detected. This measurement was obtained with AGILE observing a large portion of the sky in spinning mode. This message may be cited. =========================================================================
GCN 14516 table
GRB_name GRB130427A
GCN_number 14516
Detection_method Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 14516 SUBJECT: GRB 130427A: photo-z of possible SDSS host galaxy DATE: 13/04/30 16:59:55 GMT FROM: Alina Volnova at SAI MSU A. Vonova (IKI), L. Elenin (KIAM), A. Pozanenko (IKI) We have investigated photo-z of possible host galaxy (Melandri et al., GCN 14452, Levan et al., 14455). Using LePhare sw (Arnouts et al. 1999, MNRAS, 310, 540; Ilbert et al. 2006, A&A, 457, 841) and SDSS magnitudes we estimated a redshift of the galaxy z = 0.49 (+0.12,-0.24). This photo-z value is compatible with a spectroscopy redshift (Levan et al., GCN 14455; Xu et al., GCN 14478; Flores et al., 14491) and confirms the SDSS galaxy as the host.
GCN 14517 table
GRB_name GRB130427A
GCN_number 14517
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 14517 SUBJECT: GRB 130427A: Nishi-Harima Optical Spectroscopic Observations DATE: 13/04/30 18:06:47 GMT FROM: Akira Arai at Nishi-Harima Astro._Obs/U_of_Hyogo A. Arai, J. Takahashi, K. Morihana, S. Honda and Y. Takagi (Univ. of Hyogo) report on behalf of Nayuta team: We performed low resolution ( R ~ 500) optical spectroscopic observations of a source on the position of GRB 130427A (Masell et al., GCNC 14448) with MALLS attached to the Nayuta 2-m telescope at the Nishi-Harima Astronomical Observatory. The observations were conducted from 2013-04-27 12:48 UT to 2013-04-27 22 : 09 UT (from ~5.1 h to ~ 5.4 h after the burst). The resulting spectrum ( S/N ~ 5) shows a feature less continuum light without any emission nor absorption line features in the wavelength range between 450 nm and 680 nm. [GCN OPS NOTE(30apr13): Per operator, I have corrected a mistake I made in assigning the affiliation for this submitor.]
GCN 14518 table
GRB_name GRB130427A
GCN_number 14518
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 14518 SUBJECT: GRB 130427A: Continued GMG optical observations DATE: 13/04/30 23:02:28 GMT FROM: Xiao-hong Zhao at Yunnan Obs X.-H. Zhao (YNAO and PSU), J. Mao (RIKEN and YNAO), L. Chang (YNAO), J.-M. Bai (YNAO) report on behalf of a larger collaboration: We again observed the afterglow of GRB 130427A (Maselli et al., GCN 14448) with 2.4m Gao-Mei-Gu (GMG) telescope from 15:46:37 UT on 2013-04-30. We used the sloan filter of r' and obtained two images with the exposure time of 900s each image. The GRB afterglow decayed to r'~19.4 with a middle time of 80.2 hrs post-burst. We thank the GMG staff, especially Jian-Duo He and Gui-Hua He for performing these observations.
GCN 14519 table
GRB_name GRB130427A
GCN_number 14519
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 14519 SUBJECT: GRB 130427A: GMRT radio detection DATE: 13/05/01 08:20:09 GMT FROM: Poonam Chandra at TIFR Poonam Chandra (NCRA-TIFR) reports on behalf of a larger team: We carried out Giant Metrewave Radio Telescope (GMRT) observations of GRB 130427A at 1390 GHz band on 2013 Apr 30.57 UT. In our preliminary analysis we detect the GRB with a flux density of 500+/-94 uJy at RA, Decl (J200) of 11 32 32.81, +27 41 56.00 which is consistent with optical position reported by Elenin et al. (GCN 14450) within error bars. We thank GMRT staff for making these observations possible. More observations are planned.
GCN 14520 table
GRB_name GRB130427A
GCN_number 14520
Detection_method Swift-BAT Det
Circular_text TITLE: GCN CIRCULAR NUMBER: 14520 SUBJECT: GRB 130427A: High-energy neutrino search DATE: 13/05/01 14:09:45 GMT FROM: Erik Blaufuss at U. Maryland/IceCube Search for high-energy neutrinos in coincidence with GRB 130427A The IceCube collaboration (icecube.wisc.edu) reports: We used the data from IceCube to perform several searches for high-energy neutrinos in spatial and temporal coincidence with GRB 130427A (A. Maselli et al., GCN 14485). The first analysis is an automated online search for muon neutrino multiplets of two or more neutrinos in coincidence within 100 seconds and 3.5 degrees. The search has a threshold of ~1 TeV and does not depend on an external GRB trigger. No such multiplet was found. A second offline analysis is a likelihood based search for muon neutrinos with energies ~1 TeV and higher, with a primary background of atmospheric neutrinos and atmospheric muons. Data was scanned in the T90=162.83 s window reported by Swift BAT (S. D. Barthelmy et al., GCN 14470), and found no neutrinos. We also performed a series of rolling time-window searches covering a window of interest of +/- 1 hour relative to the burst time and again found no neutrinos. A final search focused on neutrinos of all flavors with energies ~100 TeV and higher that have interaction vertices that fall within the detector in a window of interest of +-1 day. Because the intrinsic background for this search is very low only temporal information was used in this search. No neutrinos were found in this search. Implications with respect to neutrino fluence for this GRB will be reported elsewhere. IceCube is a kilometer cubed neutrino telescope located at the geographic South Pole sensitive to neutrinos above ~100 GeV. Previous limits on the emission of neutrinos by GRBs have been presented in R. Abbasi et al., Nature 484, 351354 (2012). A description of the multiplet search is found in R. Abbasi et al., A&A 539, A60 (2012). Funding acknowledgement and author list for IceCube are listed [http://icecube.wisc.edu/collaboration/authors/current here]
GCN 14521 table
GRB_name GRB130427A
GCN_number 14521
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 14521 SUBJECT: GRB 130427A: ABT optical observations DATE: 13/05/01 14:15:39 GMT FROM: Klaas Wiersema at U Leicester I. van de Stadt (AWSV Metius, the Netherlands), K. Wiersema (U. of Leicester), T. Bekkers (AWSV Metius), M. Seynen (AWSV Metius) and F. Nieuwenhout (AWSV Metius) report: We observed the afterglow of GRB 130427A with the ABT, a 10-inch remote controlled observatory in Alkmaar, The Netherlands. In a series of V band exposures the afterglow is detected with V=18.70 +/- 0.13 mag at midtime 1.633 days after burst.
GCN 14522 table
GRB_name GRB130427A
GCN_number 14522
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 14522 SUBJECT: GRB 130427A: VLA 20 GHz detection DATE: 13/05/01 14:19:24 GMT FROM: Alessandra Corsi at GWU A. Corsi (GWU) reports on behalf of a larger collaboration: We imaged the position of GRB 130427A (Maselli et al., GCN 14448) with the Very Large Array in the 20-22 GHz frequency band, starting at about 1.9 days after the burst. A provisional reduction shows a source consistent with the location of the GRB optical (e.g., Elenin et al., GCN 14450; Perley et al., GCN 14451) and radio (e.g., Zauderer et al., GCN 14480) afterglow. At this time and frequency (~21 GHz), we estimate a preliminary flux of about 1.3 mJy. Further observations are planned. We thank the VLA staff for their support.
GCN 14523 table
GRB_name GRB130427A
GCN_number 14523
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 14523 SUBJECT: GRB 130427A: SARA-N optical observations DATE: 13/05/01 20:29:14 GMT FROM: Dieter Hartmann at Clemson.U Aman Kaur, Dieter Hartmann (Clemson University), and William C. Keel (U. of Alabama, Tuscaloosa), report: We continued our observations of GRB 130427A (Maselli, et al., GCN 14448) with the SARA 0.9m telescope at KPNO (http://saraobservatory.org) starting on April 29. We obtained a total of 190 min exposure in the R band, with a sequence of 36 five min exposures, and one ten min exposure. We detect the optical afterglow (Elenin et al; GCN14450) decay between R = 19.2 and R = 19.4 during that sequence, which implies a temporal power law decay of the flux density with a slope of alpha ~ 0.8 Magnitudes are not corrected for Galactic extinction. This message may be cited
GCN 14525 table
GRB_name GRB130427A
GCN_number 14525
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 14525 SUBJECT: GRB 130427A: KAIT optical observations DATE: 13/05/02 07:17:53 GMT FROM: Weikang Zheng at U.of Michigan WeiKang Zheng, S. Bradley Cenko, Alexei V. Filippenko and Adam Morgan (UC Berkeley) report on behalf of the KAIT GRB team: We observed the afterglow of GRB 130427A (e.g., Maselli et al., GCN 14448; Elenin et al., GCN 14450; Perley, GCN 14451) with the 0.76-m Katzman Automatic Imaging Telescope (KAIT) located at Lick Observatory on Apr. 28, 29, 30, and May 1 UT. Observations were carried out in the B, V, R, and I filters. A series of images, lasting for about an hour, was taken on each night. The afterglow is well detected in all filters, and the estimated R-band magnitudes (calibrated to SDSS, transformed to R) are as follows, with times relative to the BAT trigger: t_mid(hr) exp(s) R(mag) err 20.2 60.0 17.4 +/- 0.1 45.1 60.0 18.5 +/- 0.1 69.1 360.0 19.1 +/- 0.1 93.1 600.0 19.6 +/- 0.2 A power-law fit to the data shows the afterglow continues to decay with an index of roughly -1.0 (Itoh et al., GCN 14486). Further observations are planned.
GCN 14526 table
GRB_name GRB130427A
GCN_number 14526
Detection_method Swift-XRT Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 14526 SUBJECT: GRB 130427A: Predictions about the occurrence of a supernova DATE: 13/05/02 09:15:09 GMT FROM: Remo Rufinni at ICRA R. Ruffini, C.L. Bianco, M. Enderli, M. Muccino, A.V. Penacchioni, G.B. Pisani, J.A. Rueda, N. Sahakyan, Y. Wang, L. Izzo report: The late x ray observations of GRB 130427A by Swift-XRT clearly evidence a pattern typical of a family of GRBs associated to supernova (SN) following the Induce Gravitational Collapse (IGC) paradigm (Rueda & Ruffini 2012; Pisani et al. 2013). We assume that the luminosity of the possible SN associated to GRB 130427A would be the one of 1998bw, as found in the IGC sample described in Pisani et al. 2013. Assuming the intergalactic absorption in the I-band (which corresponds to the R-band rest-frame) and the intrinsic one, assuming a Milky Way type for the host galaxy, we obtain a magnitude expected for the peak of the SN of I = 22 - 23 occurring 13-15 days after the GRB trigger, namely between the 10th and the 12th of May 2013. Further optical and radio observations are encouraged.
GCN 14534 table
GRB_name GRB130427A
GCN_number 14534
Detection_method MITSuME
Circular_text TITLE: GCN CIRCULAR NUMBER: 14534 SUBJECT: GRB 130427A: MITSuME Ishigakijima Optical Observation after 5 days DATE: 13/05/03 00:10:46 GMT FROM: Daisuke Kuroda at OAO/NAOJ D. Kuroda (OAO, NAOJ), H. Hanayama, T. Miyaji, J. Watanabe (IAO, NAOJ), K. Yanagisawa (OAO, NAOJ), S.Nagayama (NAOJ), M. Yoshida (Hiroshima), K. Ohta (Kyoto) and N. Kawai(Tokyo Tech) report on behalf of the MITSuME collaboration: We observed the field of GRB 130427A (Masell et al., GCNC 14448) with the optical three color (g', Rc and Ic) CCD camera attached to the Murikabushi 1m telescope of Ishigakijima Astronomical Observatory. We detected the previously reported afterglow (Elenin et al., GCNC 14450) in only Rc-band. The observation started on 2013-05-02 13:08:42 UT (~5.2 days after the burst). Photometric result and three sigma upper limits of the OT are listed below. We used SDSS catalog for flux calibration. #T0+[day] MID-UT T-EXP[sec] g' Rc Rc_err Ic --------------------------------------------------------- 5.25248 13:51:30 540.0 >20.7 20.3 0.3 >19.1 --------------------------------------------------------- T0+ : Elapsed time after the burst [day] T-EXP: Total Exposure time [sec]
GCN 14538 table
GRB_name GRB130427A
GCN_number 14538
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 14538 SUBJECT: GRB 130427A: Pan-STARRS 1 optical observations DATE: 13/05/03 04:00:34 GMT FROM: Heather Flewelling at IfA/Hawaii H. Flewelling, A. Schultz, N. Primak, K. C. Chambers, E. A. Magnier, W. Sweeney, C. Z. Waters, S. Chastel, M. E. Huber, I. Smith, report on behalf of Pan-STARRS 1: Pan-STARRS 1, a 1.8 m survey telescope located at Haleakala, Hawaii, observed GRB 130427A (Masell et al., GCNC 14448) a total of 4 times in the z and y filters using the 1.4 Gigapixel camera, in the course of normal survey operations. PS1 detected the afterglow (Elenin et al., GCNC 14450), and the observations were calibrated with the "ubercal" technique (Schafly et al 2011) and the PS1 reference catalog (Magnier et al 2012). The results are: t_mid(hr) exp(s) filter mag 108.18 80.0 y 19.52 +/- 0.10 108.21 80.0 y 19.66 +/- 0.09 111.35 60.0 z 19.84 +/- 0.07 111.37 60.0 z 19.81 +/- 0.06 Note the host galaxy pre-outburst has been observed in the PS1 3pi survey and thus photometry of the host galaxy is available. This discovery was made possible by the PS1 system operated by the PS1 Science Consortium and its member institutions ( http://www.ps1sc.org/PS1_System_GCN.shtml ). We thank the telescope operators of the PS1 telescope for their support.
GCN 14549 table
GRB_name GRB130427A
GCN_number 14549
Detection_method Fermi GBM Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 14549 SUBJECT: GRB 130427A: Non-observation of VHE emission with HAWC DATE: 13/05/04 01:24:00 GMT FROM: Dirk Lennarz at HAWC D. Lennarz, I. Taboada (Georgia Tech) report on behalf of the HAWC collaboration (http://www.hawc-observatory.org/collaboration/): We used data from the partially built HAWC detector to perform a search for VHE emission in temporal coincidence with GRB 130427A (A. Maselli et al., GCN 14448). This search was conducted using the scaler data acquisition only, as the main data acquisition was not operational at the time. At the time of the GBM trigger, the elevation of the burst in HAWC's field of view, was only 33.13 degrees and setting. The sensitivity of HAWC at this elevation is more than 2 orders of magnitude poorer than near the zenith. Furthermore, while near zenith the nominal threshold of the scaler system is a few GeV, towards the horizon the nominal threshold is much higher. We used six search windows with respect to the GBM trigger time: one in the range 0 s to 20 s, which covers the bright structured peak seen by Fermi-GBM that seems to be correlated with the Fermi-LAT emission (S. Zhu et al., GCN 14508), an extended window from -5 s to 55 s and a window from -5 s to 145 s, which is slightly larger than the T90 reported by GBM. We also searched around the second peak in the GBM light curve (120 s to 300 s), -10 s to 10 s around the time of the highest energy LAT photon and in an extended window from -10 s to 290 s. We find a deviation of +38960 / -77884 / -337877 / -165991 / -519485 / -1036 of the global PMT count with respect to a moving average in the six time windows mentioned above. The p-value for these deviations assuming background hypothesis are 17 % / 78 % / 95 % / 71 % / 90 % and 50 % respectively. Our observations are consistent with background only. The implications of this non-detection with respect to the VHE fluence of this GRB will be reported elsewhere. HAWC is a gamma-ray detector under construction in Central Mexico. It currently consists of 29 operational Water Cherenkov Detectors out of 300 planned. A detailed description of the sensitivity of HAWC to GRBs can be found in A.U. Abeysekara et al., Astroparticle Physics 35, 641-–650 (2012).
GCN 14579 table
GRB_name GRB130427A
GCN_number 14579
Detection_method correction
Circular_text TITLE: GCN CIRCULAR NUMBER: 14579 SUBJECT: GRB 130427A: correction to GCN 14487 DATE: 13/05/05 21:50:56 GMT FROM: Dmitry Frederiks at Ioffe Institute D. Frederiks, on behalf of the Konus-Wind team, reports: We have also found a typo in our GCN Circ. 14487 "Konus-Wind observation of GRB 130427A": the correct energy range for the total K-W energy fluence and the peak flux estimations for GRB 130427A is 20-10000 keV, not "20 - 1200 keV", as mentioned. The 20-10000 keV range is a standard for K-W estimations of GRB energetics in the observer frame. We thank D.A.Kann for his help in clearing this issue and sorry again for the inconvenience.
GCN 14582 table
GRB_name GRB130427A
GCN_number 14582
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 14582 SUBJECT: GRB 130427A: optical observations in CrAO DATE: 13/05/05 22:29:40 GMT FROM: Alexei Pozanenko at IKI, Moscow V. Rumyantsev (CrAO), K.Antoniuk (CrAO), D. Shakhovskoy (CrAO), A. Pozanenko (IKI) report on behalf of larger GRB follow-up collaboration: We continue observation of the Swift GRB 130427A (Maselli et al., GCN 14448) with AZT-11 telescope of CrAO observatory. Preliminary photometry the optical afterglow of GRB 130427A (Maselli et al., GCN 14448, Elenin et al. GCN 14450, Perley GCN 14451) is following T_start (UT) T0+ Filter Exp. OT mid,days s mag 2013-05-02T19:34:45.35 5.5618 R 6120 19.75 +/- 0.15 2013-05-03T20:41:27.17 6.5581 R 3600 20.30 +/- 0.25 2013-05-04T18:26:22.25 7.4747 R 5400 20.20 +/- 0.18 Photometry is based on SDSS star SDSS id B eB V eV R eR I eI J113220,11+274133,5 17,421 0,020 16,911 0,020 16,561 0,015 16,124 0,016
GCN 14590 table
GRB_name GRB130427A
GCN_number 14590
Detection_method Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 14590 SUBJECT: GRB 130427A: RHESSI observations DATE: 13/05/06 17:37:44 GMT FROM: Kevin Hurley at UCBerkeley/SSL David M. Smith (UC Santa Cruz), Andre Csillaghy (Fachhochschule Nordwestschweiz), Kevin Hurley (UC Berkeley), Hugh Hudson (UC Berkeley, U. Glasgow), Steven Boggs (UC Berkeley), and Andrew Inglis (NASA Goddard/CUA) report: The Reuven Ramaty High-Energy Solar Spectroscopic Imager (RHESSI) satellite observed the prompt emission of GRB 130427A (Maselli et al. , GCN 14448), with usable data over the approximate range 50 keV to 15 MeV, and a time resolution of 1us on each photon recorded. Absolute timing accuracy is ~1ms. Since the GRB was 122 degrees from the Sun, the photons entered through the rear of the spectrometer. The lightcurve of the main outburst in three energy bands is shown binned to 25ms resolution at: http://scipp.ucsc.edu/~dsmith/rhessi/grb/130427a_longplot.gif The black, red, and orange lightcurves represent the energy ranges 50 keV to 1 MeV, 1-5 MeV, and 5-15 MeV, respectively. The lightcurve of the slower, fainter peak of the GRB, about two minutes after the primary outburst, is shown here: http://scipp.ucsc.edu/~dsmith/rhessi/grb/130427a_lateplot.gif The black, red, and orange lightcurves in this case represent the energy ranges 50-200 keV, 200-500 keV, and 500 keV to 1 MeV, respectively. RHESSI data are publicly available. We invite anyone intending to use the RHESSI data to consult with us about instrumental issues associated with the observation.
GCN 14592 table
GRB_name GRB130427A
GCN_number 14592
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 14592 SUBJECT: GRB 130427A: Tautenburg afterglow observations DATE: 13/05/06 22:41:33 GMT FROM: Alexander Kann at TLS Tautenburg D. A. Kann, B. Stecklum, and F. Ludwig (TLS Tautenburg) report: We observed the optical afterglow (Elenin et al., GCN 14450) of the nearby (Levan et al., GCN 14455), extremely bright GRB 130427A (Maselli et al., GCN 14448; Zhu et al., GCN 14471; von Kienlin, GCN 14473; Golenetskii et al., GCN 14487) with the 1.34m Schmidt telescope of the Thueringer Landessternwarte Tautenburg equipped with a 4k CCD camera under good weather conditions. We obtained 3 x 600 sec frames in the Rc band. The afterglow is detected in each frame. Using the nearby star given in Rumyantsev et al. (GCN 14582), we derive a preliminary magnitude of Rc = 20.27 +/- 0.07 at 8.55173 days after the GRB. This value is in good agreement with detections from the last few days (Kuroda et al., GCN 14534; Rumyantsev et al., GCN 14582). The afterglow does not yet show clear signs of flattening associated with either a rising supernova component or a significant contribution from the underlying host galaxy. This message may be cited.
GCN 14596 table
GRB_name GRB130427A
GCN_number 14596
Detection_method Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 14596 SUBJECT: GRB 130427A: Amateur observations from Sweden DATE: 13/05/07 19:05:46 GMT FROM: Lars Hermansson at Uppsala Amateur Astronomers L. Hermansson, P. Holmstrm, M. Johansson (Sandvreten Observatory, Sweden) We observed the field of GRB 130427A (Maselli et al., GCN 14448; Elenin et al., GCN 14450) with the 0.45 m f/4.5 Newton located at Sandvreten Observatory, Sweden. Observations were obtained between 2013-Apr-27 22:29:03 and 23:48:43 UT. Two images each were obtained in each of B, V, Rc and Ic bands with Schler Johnson-Cousins photometric filters and an SBIG ST-7E CCD. The following magnitudes were obtained from the observations with Maxim DL software using four SDSS comparison stars transformed to the BVRI system using Lupton (2005). Magnitudes are not corrected for extinction. Filter Tmid (T0+day) Exp (s) Mag Err B 0.65231 2x600 17.74 0.06 V 0.63317 2x300 17.38 0.03 Rc 0.61726 2x300 16.99 0.03 Ic 0.66821 2x300 16.78 0.05 We wish to thank D. A. Kann and the Cosmoquest forum for alerting us to GRB 130427A. We are also grateful for the guidance D.A. Kann provided during the preparation of this report.
GCN 14597 table
GRB_name GRB130427A
GCN_number 14597
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 14597 SUBJECT: GRB 130427A: Excess optical emission consistent with an emerging supernova DATE: 13/05/07 21:28:28 GMT FROM: Dong Xu at DARK/NBI D. Xu (DARK/NBI), A. de Ugarte Postigo (IAA-CSIC, DARK/NBI), T. Kruehler, D. Malesani (DARK/NBI), G. Leloudas (OKC, Stockholm and DARK/NBI), J.P.U. Fynbo, J. Hjorth, (DARK/NBI), S. Schulze (PUC and MCSS), P. Jakobsson, Z. Cano (U. Iceland), J. Gorosabel (IAA-CSIC/UPV-EHU), report: We have been monitoring the optical counterpart of GRB 130427A (Maselli et al., GCN 14448; Elenin et al., 14450) starting 12.85 hr after the GRB trigger (Xu et al., GCN 14478), mainly using the 2.5 Nordic Optical Telescope (NOT) equipped with the ALFOSC camera. Observations were carried out using the SDSS filters. The light curve between ~1.0 and 5.0 days after the trigger (observer frame) is well fit by a power law with decay index 1.3. Starting from day 5.0, however, the light curve gradually flattens. The flattening, albeit reduced, is still evident after subtracting the (known) flux contribution of the host galaxy. In particular, clear flux in excess of the afterglow and host contribution is apparent on May 5 and 6, that is 8.6 and 9.6 days after the GRB. Photometry in the Sloan griz filters was secured during the night of May 6. After subtracting from the observed flux the host contribution, and correcting for the (small) Galactic extinction, the SED clearly deviates from a power-law, in sharp contrast with our earlier measurements and the typical spectrum of GRB afterglows. Instead, the griz SED shows a broad hump peaking in the i and r bands, which is roughly consistent with the spectrum of other broad-lined SNe associated with GRBs at comparable epochs (e.g., SN 1998bw: Patat et al. ApJ, 555 900; SN 2006aj: Pian et al., Nat. 442,1011). The flattening in the decay, the change of the spectral shape, and the overall flux level are all consistent with the emergence of a SN, though detailed spectroscopy and long-term monitoring will be required to fully assess the nature of the flux excess.
GCN 14598 table
GRB_name GRB130427A
GCN_number 14598
Detection_method Swift Det
t_trigger 16:43:55 UTC
Circular_text TITLE: GCN CIRCULAR NUMBER: 14598 SUBJECT: GRB 130427A, Watcher afterglow detection DATE: 13/05/07 22:00:53 GMT FROM: Martin Topinka at UCD, Dublin Martin Topinka, Lorraine Hanlon, Pete Tisdall, Seamus Meehan, Antonio Martin-Carrillo (UCD, Dublin) and Petr Kubánek (FZÚ AVČR, Praha) on behalf of the Watcher telescope team, report: We followed the Swift detection of GRB 130427A (Maselli et al., GCN 14448, Swift trigger 554620) with the Watcher robotic telescope (D=40cm) located at Boyden Observatory, near Bloemfontein in South Africa. We started imaging the field at 16:43:55 UT on 2013-04-27 (i.e. 8.9 hr after the BAT trigger) taking 2 minute exposures in the clear filter using an Andor CCD camera. The optical afterglow (Elenin et al., GCN 14450) is clearly detected. Preliminary analysis of some of the initial images gives a magnitude for the optical afterglow of 16.59+/-0.04 @ 17:00:35 UT and 16.79+/-0.07 @ 18:59:13 UT. Magnitudes were estimated using several nearby USNO-B1 stars as references and are not corrected for galactic dust extinction. Further analysis of these images is on-going. The field continues to be regularly observed with Watcher. This message is quotable in publications.
GCN 14605 table
GRB_name GRB130427A
GCN_number 14605
Detection_method Optical
redshift 0.3400
Circular_text TITLE: GCN CIRCULAR NUMBER: 14605 SUBJECT: GRB 130427A, LBT optical spectrum DATE: 13/05/08 15:46:33 GMT FROM: Peter Garnavich at U of Notre Dame P. Garnavich (Notre Dame) reports: A spectrum of the GRB 130427A afterglow was obtained with the Large Binocular Telescope (LBT+MODS1 instrument) on 2013 May 7.15 (UT), 9.8 days after the burst. The spectrum covers 340 nm to 950 nm and is dominated by a power-law continuum. Narrow Balmer, [OII], [OIII] emission lines, and MgII and MgI absorption lines from the host galaxy are present at a redshift of 0.340. The LBT spectrum shows no obvious undulations characteristic of a broad-lined type Ic supernova such as SN 1998bw. In contrast, a 98bw-like supernova was detectable from GRB 030329 around seven days after its burst (Stanek et al. 2003, ApJ, 591, L17). This early detection was primarily due to the prominent peak seen around 500 nm (rest frame) in broad-lined type Ic events. Adding a pre-maximum spectrum of SN 1998bw (Patat et al. 2001, ApJ, 555, 900) to a power-law continuum suggests that any 98bw-like supernova is at least an R-band magnitude fainter than the afterglow 10 days after the GRB 130427A burst. I thank Rick Pogge, Paul Martini and Scott Adams for help in obtaining the spectra. The LBT is an international collaboration among institutions in the United States, Italy and Germany. LBT Corporation partners are: The University of Arizona on behalf of the Arizona university system; Istituto Nazionale di Astrofisica, Italy; LBT Beteiligungsgesellschaft, Germany, representing the Max-Planck Society, the Astrophysical Institute Potsdam, and Heidelberg University; The Ohio State University, and The Research Corporation, on behalf of The University of Notre Dame, University of Minnesota and University of Virginia.
GCN 14606 table
GRB_name GRB130427A
GCN_number 14606
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 14606 SUBJECT: GRB 130427A: Continued RATIR Optical and NIR Observations DATE: 13/05/08 16:34:04 GMT FROM: Alan M. Watson at Instituto de Astronomia UNAM Alan M. Watson (UNAM), Nat Butler (ASU), Alexander Kutyrev (GSFC), William H. Lee (UNAM), Michael G. Richer (UNAM), Chris Klein (UCB), Ori Fox (UCB) J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (UCSC), Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico Ramirez-Ruiz (UCSC), Jos A. de Diego (UNAM), Leonid Georgiev (UNAM), Jess Gonzlez (UNAM), Carlos Romn-Ziga (UNAM), Neil Gehrels (GSFC), and Harvey Moseley (GSFC) report: We have been monitoring GRB 130427A with the Reionization and Transients Infrared Camera (RATIR; www.ratir.org) on the 1.5m Harold Johnson Telescope at the Observatorio Astronmico Nacional on Sierra San Pedro Mrtir. We have precise and homogeneous photometry for all nights except 2013 May 6. During the first night the optical afterglow is well-fitted by a power law with an index of -1. However, around 1 day after the burst there is a break, and the power law steepens. Our photometry in gri from 2 to 11 days is well-fitted by a power law with an index very close to -1.5 plus a constant contribution with i = 21.23 0.05, g-i = 0.74 0.12, and r-i = 0.05 0.05, consistent with the SDSS DR9 photometry of the presumed host galaxy. We see no evidence for an additional component such as the one mentioned by Xu et al. (GCN Circular 14597). Further observations are planned. We thank the staff of the Observatorio Astronmico Nacional in San Pedro Mrtir.
GCN 14608 table
GRB_name GRB130427A
GCN_number 14608
Detection_method correction
Circular_text TITLE: GCN CIRCULAR NUMBER: 14608 SUBJECT: GRB 130427A: Ten nights of Skynet/PROMPT/GORT observations DATE: 13/05/08 19:14:43 GMT FROM: Adam S. Trotter at UNC-Chapel Hill/PROMPT/Skynet A. Trotter, D. Reichart, J. Haislip, A. LaCluyze, K. McLin, L. Cominsky, T. Berger, H. T. Cromartie, R. Egger, A. Foster, N. Frank, K. Ivarsen, M. Maples, J. Moore, M. Nysewander, E. Speckhard, and J. A. Crain report: Skynet continued observing the Swift/XRT localization of GRB 130427A (Maselli et al., GCN 14448, Swift trigger #554620) with four 16" telescopes of the PROMPT array at CTIO, Chile (BVRI bands), and with the 14" GLAST Optical Robotic Telescope (GORT) at the Hume Observatory in California (RcIc bands). Our observations span 10 nights, from t=0.65 to 10.8 days post-trigger. Skynet has taken 2684 160-second exposures on the 4 PROMPT telescopes, and 360 160-second exposures on GORT, or a total of over 135 hours on source. We performed photometry on each exposure, calibrated to two SDSS stars in the field. We stacked exposures to improve sensitivity, in groups ranging from 3 exposures on night 1, to 60 exposures on night 10. We detect a fading afterglow in BVRI at the position reported by Elenin et al. (GCN 14450), which is ~50" south of the initial XRT localization. From night 2 onwards, the light curves fade with an approximate power law index alpha=-1 (with no corrections for the known host galaxy flux). We see some evidence for flattening of the I-band light curve beginning at t~8 days, and of the R-band curve at t~10 days, though it is not clear whether this is due to host galaxy contamination or to an intrinsic re-brightening. A preliminary light curve including all Skynet observations through t=10.8 days is at: http://skynet.unc.edu/grb/grb130427a_10.png See Trotter et al. (GCN 14497, GCN 14510) for descriptions and light curves of the first and second nights' observations. Further Skynet observations are ongoing.
GCN 14615 table
GRB_name GRB130427A
GCN_number 14615
Detection_method Optical
redshift 0.3400
Circular_text TITLE: GCN CIRCULAR NUMBER: 14615 SUBJECT: GRB 130427A: Keck/LRIS Observations DATE: 13/05/09 15:39:04 GMT FROM: Daniel Perley at Caltech D. A. Perley and S. Tang (Caltech) report: On the night of 2013-05-09 UT we observed the location of GRB 130427A with the Low Resolution Imaging Spectrometer (LRIS) on the Keck I 10m telescope, during excellent weather conditions (clear skies and 0.7 arcsecond seeing). In a pair of 90 second g-band images we clearly detect the transient superimposed on a faint, extended source that we identify as the host galaxy. While blended with the light of the transient, the diameter of this extended emission is approximately 3 arcseconds, corresponding to a physical size of ~14 kpc at a redshift of z=0.34. The magnitude of the transient at this time (within a 1" aperture centered on the optical position) is: g = 21.23 +/- 0.04 mag (t = 12.00 days) This is consistent (within uncertainties) with the rate of decay seen in recent P60 observations between 1-8 days post-GRB after subtraction of the host galaxy. We also acquired a deep sequence of spectroscopic observations (2000 sec total integration) with LRIS, covering a wavelength range from approximately 3250 to 10300 Angstroms. We observe no broad features or other evidence of contribution of a supernova to the spectrum at this time, similar to as reported from LBT observations two nights previously (Garnavich et al., GCN 14605.) We thank and S. R. Kulkarni and the PTF collaboration for these observations.
GCN 14617 table
GRB_name GRB130427A
GCN_number 14617
Detection_method Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 14617 SUBJECT: GRB 130427A: host galaxy observations DATE: 13/05/09 20:03:02 GMT FROM: Klaas Wiersema at U Leicester K. Wiersema (U. of Leicester), O. Vaduvescu (ING), N. Tanvir (U. of Leicester), A. Levan (Warwick) and O. Hartoog (U. of Amsterdam) report: We observed the position of GRB 130427A with the 4.2m William Herschel telescope, using the PFIP camera, on May 8th, under good seeing conditions (0.7 arcseconds). Exposures of 4x600 seconds were obtained using a narrowband filter covering the [O II] emission line doublet (3728 A) at the redshift of the GRB (z=0.3399; Levan et al., Xu et al. and Flores et al.; GCN 14455, 14478, 14491). We used this filter to obtain the best visibility of the host galaxy against the bright afterglow and possible supernova contribution. The resulting data show a clear detection of the host galaxy. The GRB is located near, but somewhat offset from, a brighter patch in the host. The host is an irregular galaxy, with a broadly elliptical shape. The GRB is located North-West of the majority of extended, smooth, host emission - a convenient choice in spectrograph slit position angle may minimize host contamination and aid in identification of SN signatures. The long axis of the host is approximately oriented along 70 degrees position angle (where North=0, East = 90 degrees), and is approximately 3.4 arcseconds in length. A jpg finder chart of the [OII] imaging can be found here: http://www.star.le.ac.uk/~kw113/grb130427A/hostgalaxy_130427a.jpg [GCN OPS NOTE(09may13): Per author's request, the "Apr 8" was changed to "May 8" in the first sentence.]
GCN 14631 table
GRB_name GRB130427A
GCN_number 14631
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 14631 SUBJECT: GRB 130427A: Tautenburg 2nd epoch: No break, no clear SN DATE: 13/05/14 02:39:21 GMT FROM: Alexander Kann at TLS Tautenburg D. A. Kann, B. Stecklum, and C. Hoegner (TLS Tautenburg) report: We observed the optical afterglow position (Elenin et al., GCN 14450) of GRB 130427A (Maselli et al., GCN 14448) with the 1.34m Schmidt telescope of the Thueringer Landessternwarte Tautenburg equipped with the 2k CCD camera under good weather conditions. We obtained 3 x 600 sec frames in the Rc band. The afterglow is detected in each frame. Using the nearby star given in Rumyantsev et al. (GCN 14582) and also used in our first epoch observations (Kann et al., GCN 14592), we derive a preliminary magnitude of Rc = 20.37 +/- 0.07 at 15.54806 days after the GRB. This magnitude is only insignificantly fainter than the one we derived in the first epoch, evidencing a clear flattening (see also Xu et al., GCN 14597). The host galaxy is expected to have about 21st magnitude in Rc (Vega) following r' = 21.26 from SDSS (see, e.g., Watson et al., GCN 14606). Subtracting this magnitude from our detection yields a magnitude for the optical transient of ~ 21.2 +/- 0.2. This value agrees well with an extrapolation of the earlier slope, implying that no further break has occurred in the optical light curve (in agreement with the X-ray decay, which shows a very similar slope). This implies either that the post-jet break decay is among the most shallow known, or that a jet break has still not occurred, pushing GRB 130427A further into the territory of hyper- luminous events (Fan et al., arXiv:1305.1261, though see Laskar et al., arXiv:1305.2453). The situation concerning a rising supernova is still unclear. Xu et al. (GCN 14597) claimed a host-independent flattening and spectral change, which was afterwards disputed on photometric (Watson et al., GCN 14606; Perley & Tang, GCN 14615) and spectroscopic (Garnavich, GCN 14605; Perley & Tang, GCN 14615) grounds. Our measurement offers no solution to this conundrum, but it is possible that the SN, even if as luminous as SN 1998bw, will peak at a magnitude significantly fainter than the host galaxy and afterglow (Ruffini et al., GCN 14526), making detection more difficult than even in the case of GRB 030329/SN 2003dh. We wish to thank T. Kruehler for discussions relating to the host galaxy. This message may be cited.
GCN 14645 table
GRB_name GRB130427A
GCN_number 14645
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 14645 SUBJECT: GRB 130427A: optical observations DATE: 13/05/14 20:23:42 GMT FROM: Alexei Pozanenko at IKI, Moscow A. Volnova (IKI), I. Korobtsev (ISTP), E. Klunko (ISTP), A. Pozanenko (IKI) on behalf of larger GRB follow-up collaboration: We continue observation of the Swift GRB 130427A (Maselli et al., GCN 14448) with AZT-33IK telescope of Sayan observatory (Mondy). The afterglow (Elenin et al. GCN 14450, Perley GCN 14451) is clearly detected. The brightness of the afterglow+host is following: UT start, t-t0 Filter Exp. OT (mid, days) (s) (mag.) 2013-05-13T15:20:00 16.3346 R 3600 20.66 +/- 0.06 2013-05-14T14:24:35 17.2968 R 3600 20.63 +/- 0.07 The photometry is based on the same star reported by Rumyantsev et al. (GCN 14582). After subtraction of a suggested brightness (R, Vega)of the host galaxy (e.g. Watson et al., GCN 14606; Kann et al., GCN 14631) from our photometric values, our light curve can be approximated (in general) by a single power law starting at ~ 0.6 days after burst trigger. Indeed our early observations suggest some flattening between 6.5 - 13 days (Xu et al., GCN 14597; Kann et al., GCN 14631). It could be due to a SN or due to a wide bump analogous to bumps observed early in the light curve. However photometry is still preliminary and more detailed calibration/intercalibration is necessary.
GCN 14646 table
GRB_name GRB130427A
GCN_number 14646
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 14646 SUBJECT: GRB 130427A: Spectroscopic detection of the SN from the 10.4m GTC DATE: 13/05/14 21:21:33 GMT FROM: Antonio de Ugarte Postigo at IAA-CSIC A. de Ugarte Postigo (IAA-CSIC, DARK/NBI), D. Xu (DARK/NBI), G. Leloudas (OKC, Stockholm, DARK/NBI), T. Kruehler, D. Malesani (DARK/NBI), J. Gorosabel (IAA-CSIC, UPV/EHU), Z. Cano (U. Iceland), C.C. Thoene, R. Sanchez-Ramirez (IAA-CSIC), S. Schulze (PUC and MCSS), J.P.U. Fynbo, J. Hjorth (DARK/NBI), P. Jakobsson (U. Iceland) and A. Cabrera-Lavers (IAC-ULL) report on behalf of a larger collaboration: We obtained spectroscopy of the optical counterpart and host galaxy of GRB 130427A (Maselli et al., GCN 14448; Elenin et al., GCN 14450) with the 10.4m GTC telescope, 16.7 days after the GRB onset. This is 12.5 days in the host galaxy rest-frame (z = 0.34; Levan et al. GCN 14455, Xu et al. GCN 14478 and Flores et al. GCN 1449). Observations consisted of 4x1200s with the R500R grism, covering the range between 4800 and 10000 AA with a resolution of ~600. The slit was oriented to cover both the afterglow and the host galaxy centre. The spectrum has a strong contribution from the host galaxy. To overcome this, we built a synthetic host galaxy spectrum based on the SDSS (DR9) photometry using LePhare (version 2.2, Arnouts et al. 1999, MNRAS, 310, 540; Ilbert et al. 2006, A&A, 457, 841). We then subtracted this host galaxy template from the GTC spectrum to obtain a "clean" spectrum of the counterpart associated to GRB 130427A. The resulting spectrum is that of a broad-lined Ic SN, with a prominent bump at ~6800 A observer frame. In particular, we obtain an excellent match with the spectrum of SN 2010bh at 12.7 (rest-frame) days after GRB 100316D (Bufano et al. 2012, ApJ 753, 67). We stress that this conclusion is independent of the host galaxy model adopted. By running SNID (Blondin & Tonry 2007, ApJ, 666, 1024) on the original spectrum (i.e. including host contamination), we still obtain good matches with a series of broad-lined Type Ic SNe, including SNe 1998bw, 1997ef, 2002ap and 2006aj, albeit at a lower redshift. The fact that SNID suggests a lower redshift is explained by the fact that SN 2010bh had high expansion velocities, reaching ~34000 km/s at similar phases (Bufano et al. 2012, ApJ 753, 67), which we suggest is also the case for the SN associated with GRB 130427A. A figure of our preliminary analysis can be seen at: http://www.iaa.es/~deugarte/GRBs/130427A/130427A_GTC.jpg We acknowledge excellent support from the GTC staff. [GCN OPS NOTE(14may13): Per author's request, ZCwas added to the author list.]
GCN 14662 table
GRB_name GRB130427A
GCN_number 14662
Detection_method Swift-XRT Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 14662 SUBJECT: GRB 130427A: Skynet detections of a possible supernova DATE: 13/05/15 17:02:50 GMT FROM: Adam S. Trotter at UNC-Chapel Hill/PROMPT/Skynet A. Trotter, D. Reichart, J. Haislip, A. LaCluyze, K. McLin, L. Cominsky, A. Smith, D. Caton, L. Hawkins, B. Holmes, T. Linder, T. Berger, H. T. Cromartie, R. Egger, A. Foster, N. Frank, K. Ivarsen, M. Maples, J. Moore, M. Nysewander, E. Speckhard, and J. A. Crain report: Skynet has continued observing the Swift/XRT localization of GRB 130427A (Maselli et al., GCN 14448, Swift trigger #554620) with: four 16" telescopes of the PROMPT array at CTIO, Chile (BVRI bands); the 14" GLAST Optical Robotic Telescope (GORT) at the Hume Observatory in California (RcIc bands); the 14" Deep Sky Observatory (DSO-14) telescope at Pisgah National Forest, NC; and the 30" telescope at the Astronomical Research Observatory (ARO-30) in Westfield, IL. Our observations now span 18 nights, from t=0.65 to 17.6 days post-trigger. Skynet has taken 3420 160-second exposures on the 4 PROMPT telescopes, 420 160-second exposures on GORT, 91 160s exposures on DSO-14 and 133 60-160s exposures on ARO-30, or a total of over 178 hours on source. We performed photometry on each exposure, calibrated to two SDSS stars in the field. We stacked exposures to improve sensitivity, in groups ranging from 3 exposures on night 1, to 60 exposures on night 18. In Trotter et al. (GCN 14608) we reported a flattening of the light curve at t~10 days. That flattening has continued, with possible chromatic bumps in V, R and I bands at ~14d, 11d and 10d, respectively. Our most recent observations, at t=17.8d, show a rebrightening in V, R and I bands; we speculate that this may be the onset of the classical supernova, which was detected spectroscopically by de Ugarte Postigo et al. (GCN 14646) at t=16.7 days. A preliminary light curve including all Skynet observations through t=17.8 days is at: http://skynet.unc.edu/grb/grb130427a_17.png Further observations are scheduled.
GCN 14666 table
GRB_name GRB130427A
GCN_number 14666
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 14666 SUBJECT: GRB 130427A: Continued RATIR Optical and NIR Observations - Photometric Evidence for a New Component DATE: 13/05/16 01:57:40 GMT FROM: Alan M. Watson at Instituto de Astronomia UNAM Alan M. Watson (UNAM), Nat Butler (ASU), Alexander Kutyrev (GSFC), William H. Lee (UNAM), Michael G. Richer (UNAM), Chris Klein (UCB), Ori Fox (UCB), J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (UCSC), Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico Ramirez-Ruiz (UCSC), Jos A. de Diego (UNAM), Leonid Georgiev (UNAM), Jess Gonzlez (UNAM), Carlos Romn-Ziga (UNAM), Neil Gehrels (GSFC), and Harvey Moseley (GSFC) report: We have continued to monitor GRB 130427A with the Reionization and Transients Infrared Camera (RATIR; www.ratir.org) on the 1.5m Harold Johnson Telescope at the Observatorio Astronmico Nacional on Sierra San Pedro Mrtir, obtaining homogenous photometry in griZYJH. We have photometry for every night except 2013 May 6. On most nights our photometric uncertainties in gri are about 2%. As we reported earlier in Watson et al. (GCN Circular 14606), the optical afterglow during the first day is well-fitted by a power law with a temporal index of -1. However, around T+1d there is a break, and the power law steepens. From T+2.5d to T+14.9d our gri photometry is well-fitted by a power law with a temporal index close to -1.5 plus a constant component consistent with the presumed SDSS host galaxy. However, our observations at T+15.9d, T+16.9d, and T+17.9d are systematically brighter than this fit. Adding a new component starting at T+15.5d with zero colors and constant magnitude significantly improves the fit (with a confidence level of better than 99.5%). The constant component has g = r = i = 24.53 0.25. We do not mean to suggest that the new component actually has zero color or constant magnitude. However, at this moment our data cannot usefully constrain anything other than a characteristic brightness. Our data, model, and residuals are shown at https://dl.dropboxusercontent.com/u/528672/GCN/2013-05-16-GRB-130427A.pdf Assuming a distance modulus of 41.26, the new component corresponds to an absolute magnitude of -16.7 0.25. If the new component is a Type 1c supernova, as suggested by de Ugarte Postigo et al. (GCN Circular 14646), we might expect the peak extinction-corrected absolute magnitude to be around -18 (Drout et al. 2011, ApJ, 741, 97). Thus, depending on the host galaxy extinction, we might be seeing this possible supernova at or just before its peak. We caution that the new component is currently about 2 magnitudes fainter than the afterglow component, which at 18.0 days is predicted to have i = 22.21 0.04 and even fainter then the galaxy, which is predicted to have i = 21.23 0.03. The relative brightnesses of the new component, the fading afterglow, and the host galaxy also have significant implications for unveiling the spectrum of the possible supernova. We further caution that from our data alone we cannot exclude the possibility that the new component might simply be a significant flattening of the late afterglow component. The largest residuals of our observations from the model (with or without the new component) are at the level of 0.05 magnitudes. We do not see the large variations reported by Trotter et al. (GCN Circular 14662). Further observations are planned. We thank the staff of the Observatorio Astronmico Nacional in San Pedro Mrtir.
GCN 14669 table
GRB_name GRB130427A
GCN_number 14669
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 14669 SUBJECT: GRB 130427A:: BTA spectroscopic observations on May 10/11. DATE: 13/05/16 21:22:08 GMT FROM: Alberto Castro-Tirado at Inst.de Astro. de Andalucia Vladimir V. Sokolov (SAO-RAS), Alberto J. Castro-Tirado (IAA-CSIC), Alexander S. Moskvitin, Elena A. Barsukova, Viktoria N. Komarova, Nikolaj V. Borisov, Azamat F. Valeev, Tatyana N. Sokolova (SAO-RAS) and Vitaly P. Goranskij (SAI-MSU, SAO-RAS), report: "We have obtained 3 epochs of spectroscopy for the GRB 130427A optical afterglow (Maselli et al. GCNC 14448, Elenin et al. GCNC 14450) with the 6-meter BTA equipped with Scorpio. The spectra (with exposure times of 4 x 900 s, 5 x 900 s and 4 x 1200 s) were taken on May 2/3, 5/6 and 10/11 respectively. We used the VPHG 550G grating which covers the 3700-7900 A spectral range and provides a 13 A spectral resolution. Narrow host galaxy lines such as 3727 A [OII], [OIII] 4959 A, 5007 A and Balmer lines are noticeable in all spectra. The measured redshift is 0.3393, in good agreement with the previously reported values (Levan et al. GCNC 14455; Xu et al. GCNC 14478; Flores et al. GCNC 14491; Garnavich GCNC 14605 and Perley & Tang, GCNC 14615). Particularly, we detect marginal excess emission in the range 6000-7000 A on the later spectrum obtained on May 10/11, which can be interpreted as evidence of the underlying SN (de Ugarte Postigo et al., GCNC 14646), what is also supported by the long-term photometric observations (Trotter et al., GCNC 14662; Watson et al., GCNC 14666). Our preliminary flux-calibrated spectra can be seen at: http://www.sao.ru/hq/grb/GRB130427A/GRB130427A_BTA_May2-10.jpg We thanks S.N. Fabrika, O.P. Zhelenkova, Yu.Yu. Balega, V.V. Vlasyuk and A.S. Moiseev for their help in obtaining the observations."
GCN 14672 table
GRB_name GRB130427A
GCN_number 14672
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 14672 SUBJECT: GRB 130427A: Konkoly optical observations DATE: 13/05/18 19:56:36 GMT FROM: Janos Kelemen at Konkoly Obs/Hungary J. Kelemen (kelemen at konkoly.hu) on behalf of the GRB OT observing program at the Konkoly Observatory. Starting on the evening of 15/05/2013 we observed the field of GRB 130427A (Maselli et al., GCN 14448) 18.5435 days after the burst, using a 60/90/180 cm Schmidt telescope located at the Mountain Station of the Konkoly Observatory equipped with an Apogee CCD camera through R filter. On the coadded R images (total exp.time 1120 sec) we detected the OT and the host galaxy as well. Based on the nearby UCAC-4 stars we provide 20.90 +/- 0.05 magnitude in the R band for the OT. The brightness of the host galaxy was not subtracted. time from GRB exp filter Mag. 18.5435 1120 s R 20.9 +/-0.05
GCN 14673 table
GRB_name GRB130427A
GCN_number 14673
Detection_method Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 14673 SUBJECT: VLT observations of GRB 130427A DATE: 13/05/18 20:47:44 GMT FROM: Andrea Melandri at INAF-OAB A. Melandri (INAF-OAB), V. D'Elia (ASDC), P. D'Avanzo (INAF-OAB), M. Della Valle (INAF-OAC), E. Pian (INAF-OAT/SNS), G. Tagliaferri (INAF- OAB) on behalf of a larger collaboration report: We have observed the field of GRB 130427A (Maselli et al., GCN 14448) for 9 epochs from t-t0=6.7 to t-t0=18.8 days after the burst event. The preliminary light curve in BVR and I bands does not show any evidence of a bump related to a SN, and it is marginally consistent with a SN component, which should be at least 2 mag fainter than 98bw at maximum. The spectrum (2x1800s) of 13 May, after comparison with SN2010bh template, is suggestive, in the range 5000A-7500A of broad GRB-SN features, but altogether, we don't find the good similarity that the GTC finds (de Ugarte-Postigo et al., CBET 3529). The spectrum of the transient (after subtraction of a galaxy template) is available at: http://www.brera.inaf.it/utenti/davanzo/grb/GRB130427A/GRB130427A.png Observations have been taken in the framework of the ESO-Program 091.D-0291 (PI E. Pian).
GCN 14686 table
GRB_name GRB130427A
GCN_number 14686
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 14686 SUBJECT: GRB 130427A / SN 2013cq: Hubble Space Telescope Observations DATE: 13/05/20 23:08:33 GMT FROM: Andrew S. Fruchter at STScI A.J. Levan (U. Warwick), A.S. Fruchter, J. Graham (STScI), N.R. Tanvir (U. Leicester), Jens Hjorth, Johan Fynbo (Dark Cosmology Centre, Copenhagen), D. Perley (Caltech), S.B. Cenko (U.C. Berkeley), E. Pian (Trieste), Z. Cano (U. Iceland) A. Pe'er (Cork), R. Hounsell (STScI), K. Mishra (ARIES, India), C. Kouveliotou (MSFC) report: We observed the optical/NIR counterpart of GRB 130427A (Maselli et al. GCN 14448) with the Hubble Space Telescope beginning at 02:23 UT on 20 May 2013. The afterglow is well detected in our multi-band observations in the UV (F336W), optical (F606W) and NIR (F160W) and is offset approximately 0.8" from the optical centroid of its host. The host itself also contains additional star forming complexes including a bright UV source approximately 0.25" from the GRB position. In the three bands we measure preliminary magnitudes of the afterglow + supernova of F336W=23.10 +/- 0.02 F606W=21.85 +/- 0.02 F160W=21.34 +/- 0.03 These magnitudes show significant curvature in the optical likely due to the underlying supernova SN 2013cq (de Ugarte Postigo CBET 3529; Xu et al. GCN 14597). If the optical light were entirely dominated by supernova emission the absolute magnitude at z=0.34 would be M_B~ -19.1 at 17 rest-frame days post burst. However, SNe are weaker UV and IR emitters and so under the naive assumption that the UV and IR bands are dominated by power-law afterglow emission with minimal supernova contribution the inferred magnitude of the supernova in the V-band (rest frame B-band) is V~23. This corresponds to an absolute magnitude of M_B ~ -17.9, approximately a magnitude fainter than the B-band peak of SN 1998bw (which occurred at a comparable epoch of 15 days post burst). However, the SN could contribute as much as one half of the flux we are seeing in the NIR and UV and there may be substantial host emission underneath the object in the optical and UV. Thus the SN magnitude should be considered very approximate. Images of the field are posted at http://www.star.le.ac.uk/~anl/GRB130427A We thank the staff of STScI for their work in rapidly scheduling these observations.