GRB090418A

This page lists all entries on GRB090418A in GRBweb

Summary IPN Swift GCN 9148 GCN 9149 GCN 9150 GCN 9151 GCN 9152 GCN 9154 GCN 9157 GCN 9162 GCN 9163 GCN 9166 GCN 9168 GCN 9175 GCN 9179 GCN 9183 GCN 9190 GCN 9196 GCN 9199 GCN 9211 GCN 9293 GCN 9329

Summary table
Variable Value Source
T0 11:07:40 UTC GCN_circulars,Swift Det
ra 269.3132° Swift
decl 33.4059° Swift
pos_error 6.47e-05° Swift
T90 56.0 s Swift
T90_start 11:07:40 UTC Swift
fluence 4.60e-06 erg/cm² Swift
redshift 1.6080 GCN_circulars,Swift Other
T100 56.0 s
GBM_located False
mjd 54939.46365740741 GCN_circulars,Swift Det
IPN table
GRB_name GRB090418A
ra 269.3333°
decl 33.4167°
pos_error 5.00e-02°
redshift 1.6080
Swift table
GRB_name GRB090418A
t_trigger 11:07:40 UTC
ra 269.3132°
decl 33.4059°
pos_error 6.47e-05°
T90 56.0 s
fluence 4.60e-06 erg/cm²
redshift 1.6080
GCN 9148 table
GRB_name GRB090418A
GCN_number 9148
Detection_method Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 9148 SUBJECT: GRB 090418 OA candidate DATE: 09/04/18 11:16:22 GMT FROM: Ryan Chornock at UC Berkeley R. Chornock, S. B. Cenko, W. Li, and A. V. Filippenko (UC Berkeley) report on behalf of the KAIT GRB team: The Katzman Automatic Imaging Telescope (KAIT) at Lick Observatory automatically slewed to the position of GRB 090418 and discovered a new new point source not present in the DSS at coordinates (J2000): 17:57:15.17 +33:24:21.1 at an unfiltered magnitude of approximately 15.8 at UT=11:10:57. Further observations are in progress.
GCN 9149 table
GRB_name GRB090418A
GCN_number 9149
Detection_method Swift Det
t_trigger 11:07:40 UTC
ra 269.3340°
decl 33.4090°
Circular_text TITLE: GCN CIRCULAR NUMBER: 9149 SUBJECT: GRB 090418: Swift detection of a burst with optical afterglow DATE: 09/04/18 11:35:24 GMT FROM: David Palmer at LANL V. Mangano (INAF-IASFPA), S. D. Barthelmy (GSFC), D. N. Burrows (PSU), P.A. Curran (MSSL-UCL), N. Gehrels (NASA/GSFC), S. T. Holland (CRESST/USRA/GSFC), E. A. Hoversten (PSU), J. Mao (INAF-OAB), P. T. O'Brien (U Leicester), D. M. Palmer (LANL), A. M. Parsons (GSFC), M. Perri (ASDC), B. A. Rowlinson (U Leicester), B. Sbarufatti (INAF-IASFPA), G. Tagliaferri (INAF-OAB), T. N. Ukwatta (GSFC/GWU), L. Vetere (PSU) and H. Ziaeepour (UCL-MSSL) report on behalf of the Swift Team: At 11:07:40 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 090418 (trigger=349510). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 269.334, +33.409 which is RA(J2000) = 17h 57m 20s Dec(J2000) = +33d 24' 31" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows two main peaks with a duration of about 70 sec. The peak count rate was ~2000 counts/sec (15-350 keV), at ~45 sec after the trigger. The XRT began observing the field at 11:09:16.3 UT, 96.1 seconds after the BAT trigger. Using promptly downlinked data we find a bright, fading, uncatalogued X-ray source with an enhanced position: RA, Dec 269.3129, 33.4055 which is equivalent to: RA(J2000) = 17h 57m 15.09s Dec(J2000) = +33d 24' 19.9" with an uncertainty of 2.1 arcseconds (radius, 90% containment). This location is 64 arcseconds from the BAT onboard position, within the BAT error circle. This position may be improved as more data are received; the latest position is available at http://www.swift.ac.uk/sper. A power-law fit to a spectrum formed from promptly downlinked event data gives a column density consistent with the Galactic value of 3.55e+20 cm^-2 (Kalberla et al. 2005). The initial flux in the 2.5 s image was 1.05e-09 erg cm^-2 s^-1 (0.2-10 keV). UVOT took a finding chart exposure of 250 seconds with the u filter starting 859 seconds after the BAT trigger. An afterglow candidate has been found in the initial data products at RA(J2000) = 17:57:15.1 = 269.31458 Dec(J2000) = +33:24:21 = +33.40583 with an estimated uncertainty of 1.0 arcsec (radius, 90% confidence, statistical + systematic). This is 1.1 arcsec from the XRT position. The estimated magnitude is u = 17.3 mag. No correction has been made for the expected extinction corresponding to E(B-V) of 0.04. Burst Advocate for this burst is V. Mangano (vanessa 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 9150 table
GRB_name GRB090418A
GCN_number 9150
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 9150 SUBJECT: GRB 090418: ROTSE-III Confirmation of Optical Counterpart DATE: 09/04/18 12:10:59 GMT FROM: Fang Yuan at ROTSE F. Yuan (U Mich), B. E. Schaefer (Louisiana State), W. Rujopakarn (Steward), report on behalf of the ROTSE collaboration: ROTSE-IIIb, located at McDonald Observatory, Texas, responded to GRB 090418 (Swift trigger 349510; Mangano et al, GCN 9149) in twilight. The first image was at 11:07:59.2 UT, 19.0 s after the burst (4.2 s after the GCN notice time). The unfiltered images are calibrated relative to USNO B1.0. We detect the optical counterpart at the KAIT and UVOT position (Chornock et al. GCN 9148; Mangano et al, GCN 9149) at the following magnitude and limit: start UT end UT mag magerr mlim(of image) -------------------------------------------------------------------------------- 11:07:59.2 11:09:06.3 15.9 0.1 17.0 11:09:19.6 11:14:02.1 15.9 0.1 16.8 11:14:11.3 11:25:31.5 - - 16.7
GCN 9151 table
GRB_name GRB090418A
GCN_number 9151
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 9151 SUBJECT: GRB 090418 Lick Redshift DATE: 09/04/18 12:34:39 GMT FROM: Ryan Chornock at UC Berkeley R. Chornock, S. B. Cenko, C. V. Griffith, M. E. Kislak, I. K. W. Kleiser, and A. V. Filippenko (UC Berkeley) report: We obtained optical spectra of the afterglow of GRB 090418 (Chornock et al., GCN 9148; Mangano et al., GCN 9149; Yuan et al., GCN 9150) using the Kast spectrograph on the Lick 3-meter telescope. Our first 900s exposure, starting at 11:21:16 UT (only 816s after the burst trigger) reveals a smooth continuum extending to the blue limit of our spectra (3450 Angs). Superposed on the continuum are absorption lines of C IV, Mg II, Fe II, Al II, and Mg I at z=1.608, which we suggest is the redshift of this burst. Further analysis is ongoing.
GCN 9152 table
GRB_name GRB090418A
GCN_number 9152
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 9152 SUBJECT: GRB 090418: PAIRITEL NIR detection DATE: 09/04/18 14:13:00 GMT FROM: Bethany Cobb at UC Berkeley B. E. Cobb and J. S. Bloom (UC Berkeley) report: We observed the optical afterglow of GRB 090418 (Mangano et al., GCN 9149) with the 1.3-m Peters Automated Infrared Imaging Telescope (PAIRITEL) beginning at 2009-04-18 11:34 UT, 26 minutes after the Swift Trigger. We detect the afterglow (Chornock et al., GCN 9148; Yuan et al., GCN 9150) in 651 sec mosaics of 7.8 sec simultaneous individual exposures in the J, H, and Ks filters. Preliminary photometry for the afterglow in these mosaics, with midtime 2009-04-18 11:43 UT (35 minutes post-burst), yields J = 17.7 +- 0.4, H = 17.5 +- 0.4, and Ks = 16.1 +- 0.4 (all magnitudes given in the Vega system), calibrated to the 2MASS system.
GCN 9154 table
GRB_name GRB090418A
GCN_number 9154
Detection_method Swift-XRT Det
ra 269.3133°
decl 33.4061°
Circular_text TITLE: GCN CIRCULAR NUMBER: 9154 SUBJECT: GRB 090418: Enhanced Swift-XRT position DATE: 09/04/18 16:00:43 GMT FROM: Phil Evans at U of Leicester M.R. Goad, J.P. Osborne, A.P. Beardmore and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team. Using 2594 s of XRT Photon Counting mode data and 5 UVOT images for GRB 090418, we find an astrometrically corrected X-ray position (using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec = 269.31329, +33.40607 which is equivalent to: RA (J2000): 17h 57m 15.19s Dec (J2000): +33d 24' 21.8" with an uncertainty of 1.7 arcsec (radius, 90% confidence). This position may be improved as more data are received. The latest position can be viewed at http://www.swift.ac.uk/xrt_positions. Position enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans et al. (2009, arXiv:0812.3662). This circular was automatically generated, and is an official product of the Swift-XRT team.
GCN 9157 table
GRB_name GRB090418A
GCN_number 9157
Detection_method Swift-BAT Det
ra 269.3200°
decl 33.4070°
Circular_text TITLE: GCN CIRCULAR NUMBER: 9157 SUBJECT: GRB 090418: Swift-BAT refined analysis DATE: 09/04/18 17:54:33 GMT FROM: Scott Barthelmy at NASA/GSFC E. E. Fenimore (LANL), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC/UMD), V. Mangano (INAF-IASFPA), D. M. Palmer (LANL), A. M. Parsons (GSFC), T. Sakamoto (GSFC/UMBC), G. Sato (ISAS), M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC), T. N. Ukwatta (GWU) (i.e. the Swift-BAT team): Using the data set from T-240 to T+705 sec from recent telemetry downlinks, we report further analysis of BAT GRB 090418 (trigger #349510) (Mangano, et al., GCN Circ. 9149). The BAT ground-calculated position is RA, Dec = 269.320, 33.407 deg, which is RA(J2000) = 17h 57m 16.8s Dec(J2000) = +33d 24' 24.4" with an uncertainty of 1.4 arcmin, (radius, sys+stat, 90% containment). The partial coding was 31%. The mask-weighted light curve shows two clusters of peaks. The first starts at ~T-8 sec, peaks at ~T+1 sec, and reaches a minimum at T+15 sec. The second cluster peaks at around T+40 sec and returns to background at ~T+70 sec. T90 (15-350 keV) is 56 +- 5 sec (estimated error including systematics). The time-averaged spectrum from T-8.5 to T+61.1 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.48 +- 0.07. The fluence in the 15-150 keV band is 4.6 +- 0.2 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T+0.06 sec in the 15-150 keV band is 1.9 +- 0.3 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/349510/BA/
GCN 9162 table
GRB_name GRB090418A
GCN_number 9162
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 9162 SUBJECT: GRB 090418A: ROTSE-III Refined Analysis DATE: 09/04/19 16:15:56 GMT FROM: Fang Yuan at ROTSE F. Yuan (U Mich) report on behalf of the ROTSE collaboration: ROTSE-IIIb, located at McDonald Observatory, Texas, responded to GRB 090418A (Swift trigger 349510; Mangano et al, GCN 9149) 19.0 s after the burst, during the gamma-ray emission, and detected the optical counterpart (Yuan et al, GCN 9150). We took 10 5-sec, 10 20-sec and 26 60-sec useful exposures before sunrise. Further analysis of single images revealed an initially rising lightcurve with two subsequent peaks at ~40s (~15.6 mag) and ~130s (~15.4 mag) before the OT dropped below our detection limit.
GCN 9163 table
GRB_name GRB090418A
GCN_number 9163
Detection_method Swift Other
ra 269.3133°
decl 33.4061°
redshift 1.6080
Circular_text TITLE: GCN CIRCULAR NUMBER: 9163 SUBJECT: GRB 090418: Swift XRT refined analysis DATE: 09/04/19 16:55:19 GMT FROM: Vanessa Mangano at INAF-IASFPA Mangano V., Sbarufatti B. (INAF-IASFPA) report on behalf of the Swift XRT Team: We have analysed the first four orbits of Swift-XRT data obtained from GRB 090418 (trigger 349510; Mangano, et al., GCN Circ. 9149), comprising 116 s taken in Windowed Timing (WT) mode, from T+102 s to T+218 s, and a total exposure of 8.5 ks in Photon Counting (PC) mode from T+219 s to the end of the observation at T+18 ks. The best position of the X-ray afterglow is the UVOT enhanced XRT position given in Goad, et al., GCN Circ. 9154, that is RA, Dec = 269.31329, +33.40607 which is equivalent to: RA (J2000): 17h 57m 15.19s Dec (J2000): +33d 24' 21.8" with an uncertainty of 1.7 arcsec (radius, 90% confidence). The 0.3-10 keV X-ray light curve is well fitted by a doubly broken pawer law, with a initial decay slope alpha1=1.7+/-0.1, a first breal at about T+245 s, an intermediate decay slope alpha2=0.35 -0.1+0.06, a second break at about T+2 ks and a final decay slope alpha3=1.39+/-0.06 If decaying at this rate, the afterglow will reach a count-rate of 6.1E-3 counts/s at T+48h. The average WT spectrum (corresponding to the initial steep decay phase) is best fitted by an absorbed power-law model, with photon index 2.0+/-0.2, and intrinsic NH=(6+/-3)E21 cm-2 (at the redshift z=1.608, Chornock, et al., GCN circ. 9151) in excess with respect to the galactic absorption value of 3.6E20 cm-2 (Kalberla et al. 2005). The average observed(unabsorbed) flux in the 0.3-10 keV band is 3.5(4.6)E-10 ergs cm-2 s-1. The average PC spectrum of the first orbit (covering the intermediate slowly decaying phase) is well fitted by an absorbed power-law model, with photon index 2.1+/-0.1, intrinsic NH=(1.2+/0.3)E22 cm-2 and average observed(unabsorbed) flux in the 0.3-10 keV band of 1.5(2.2)E-10 ergs cm-2 s-1. Finally, the average PC spectrum from T+4.2 ks to T+18 ks (orbits 2-4) is well fitted by an absorbed power-law model, with photon index 2.0+/-0.1, intrinsic NH=(1.1+/0.2)E22 cm-2 and average observed(unabsorbed) flux in the 0.3-10 keV band of 1.3(1.8)E-11 ergs cm-2 s-1. The average count-rate to observed(unabsorbed) flux conversion factor is 4.5(6.5)E-11. All quoted errors are at 90% confidence level. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00349510. This circular is an official product of the Swift-XRT team.
GCN 9166 table
GRB_name GRB090418A
GCN_number 9166
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 9166 SUBJECT: VLA radio detection of GRB 090418 DATE: 09/04/19 23:59:16 GMT FROM: Poonam Chandra at U Virginia/NRAO Poonam Chandra (RMC) and Dale A. Frail (NRAO) report on behalf of a larger collaboration: "We used the Very Large Array to observe the field of view toward the GRB 090418 (GCN 9149) at a frequency of 8.46 GHz on 2009 Apr.19.46 UT. We observed the radio afterglow of the GRB at a position J2000 RA 17:57:15.156, Dec 33:24:20.78 which is 0.39" away from the KAIT optical afterglow position reported by Chornock et al. (GCN 9148). The GRB radio afterglow flux density is 219+/-44 uJy. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc."
GCN 9168 table
GRB_name GRB090418A
GCN_number 9168
Detection_method MITSuME
Circular_text TITLE: GCN CIRCULAR NUMBER: 9168 SUBJECT: GRB 090418: Optical observations with MITSuME Okayama and Ishigaki 1m telescope DATE: 09/04/20 07:23:37 GMT FROM: Michitoshi Yoshida at Okayama Astrophysical Obs D. Kuroda, M. Yoshida, M. Isogai, K. Yanagisawa, Y. Shimizu, S. Nagayama, H. Toda, M. Isogai (NAOJ) and N. Kawai (Tokyo Tech) report on behalf of the MITSuME collaboration: We observed the field of GRB 090417B (Mangano et al. GCN 9149) with optical three color (g', Rc and Ic) CCD cameras attached to the MITSuME 50cm telescope of Okayama Astrophysical Observatory and the 1m telescope of Ishigaki-Jima Observatory. We started the observation at 13:26:42 UT, 8342s after the burst at Okayama. We could not find a new source at the position of the afterglow (Chornock et al. GCN 9148; Mangano et al. GCN 9149; Goad et al. GCN 9154). 3-sigma upper limits to our observations are the following. We used GSC2.3 catalog for flux calibration. Okayama MITSuME observation Mid-UT Td(day) EXP-T g' Rc Ic ------------------------------------------------------------- 13:56:41 0.11736 2940s (49x60s) >19.2 >19.1 >19.0 16:27:25 0.22204 5880s (98x60s) >20.5 >20.3 >20.1 ------------------------------------------------------------- Ishigaki-Jima 1m telescope observation Mid-UT Td(day) EXP-T g' Rc Ic ------------------------------------------------------------- 14:48:36 0.15342 3000s (10x300s) >20.6 >20.9 >19.9 -------------------------------------------------------------
GCN 9175 table
GRB_name GRB090418A
GCN_number 9175
Detection_method Swift-UVOT Det
ra 269.3132°
decl 33.4059°
redshift 1.6080
Circular_text TITLE: GCN CIRCULAR NUMBER: 9175 SUBJECT: GRB 090418A: Swift/UVOT Observations DATE: 09/04/20 19:47:16 GMT FROM: Stephen Holland at USRA/NASA/GSFC/SSC S. T. Holland (CRESST/GSFC/USRA) and V. Mangano (INAF-IASFPA) report on the behalf of the Swift UVOT team: The Swift/UVOT observed the field of GRB 090418A starting 84 s after the BAT trigger (Mangano, et al. 2009, GCN Circ. 9149). Settled exposures started at T+160 s. The refined UVOT position for the optical afterglow is RA (J2000) = 17:57:15.17 = 269.31321 (deg) Dec (J2000) = +33:24:21.1 = +33.40585 (deg) with an estimated uncertainty of 0.5 arcsec (radius, 90% confidence, statistical + systematic). Preliminary 3-sigma magnitudes and upper limits are Filter T_start T_stop Exp(s) Mag Err ------------------------------------------------------------- u (fc) 160 410 246 17.31 0.09 v 466 485 19 17.31 0.24 b 415 435 19 18.22 0.25 u 539 559 19 18.55 0.39 uvw1 515 835 19 >18.1 3-sigma UL uvm2 490 510 19 >17.6 3-sigma UL uvw2 441 461 19 >18.1 3-sigma UL uvw1 515 11,831 1337 20.82 0.26 114,115 131,895 2064 >22.0 3-sigma UL uvm2 490 18,413 2109 >21.8 3-sigma UL uvw2 441 16,709 1357 >21.8 3-sigma UL ------------------------------------------------------------- The quoted magnitudes have not been corrected for the expected Galactic extinction along the line of sight corresponding to a reddening of E_{B-V} = 0.04 mag (Schlegel, et al., 1998, ApJS, 500, 525). All photometry is on the UVOT flight system described in Poole et al. (2008, MNRAS, 383, 627). The detection in the uvw1 filter, combined with the lack of a detection in the uvm2 filter, is consistent with this source having a redshift of z = 1.608 (Charnock, et al., 2009, GCN Circ. 9151).
GCN 9179 table
GRB_name GRB090418A
GCN_number 9179
Detection_method Optical
ra 17.0000°
decl 33.0000°
redshift 1.6080
Circular_text TITLE: GCN CIRCULAR NUMBER: 9179 SUBJECT: GRB 090418A: optical observations DATE: 09/04/20 22:23:53 GMT FROM: Alexei Pozanenko at IKI, Moscow E. Pavlenko, V. Rumyantsev (CrAO), A. Pozanenko (IKI) report on behalf of larger GRB follow-up collaboration: We observed the error box of Swift GRB 090418A in series of BVRI exposures on Apr. 18 with Shajn telescope of CrAO. We detect the afterglow (Chornock et al., GCN 9148, Mangano et al., GCN 9149) in all filters in stacked images. Astrometry of the afterglow is RA(J2000): 17 57 15.17 Dec(J2000): +33 24 21.14 with uncertainty of 0.3 arcsec is fully compatible with reported one in GCNs 9148, 9149. Preliminary photometry of combined images is based on USNO-B1.0 1234-0288651 star RA=17:57:13.29 Dec=+33:25:00.6 is following: T0+ Filter, Exposure, mag., err. (d) (s) 0.5484 B 36x60 23.30 +/- 0.20 0.5484 R 17x60 22.23 +/- 0.14 0.5491 I 17x60 22.40 +/- 0.24 We note, that OT is ~4" North-West of bright galaxy which is also visible in POSS2. Taking the redshift z=1.608 of the GRB source (Chornock et al., GCN 9151) and the scale of ~8.6 kpc/" at that redshift it is unlikely that the galaxy is related with OT. A finding chart the combined image in I can be found at http://grb.rssi.ru/GRB090418A/GRB090418_I_ZTSh_090418.gif
GCN 9183 table
GRB_name GRB090418A
GCN_number 9183
Detection_method Swift-UVOT Det
Circular_text TITLE: GCN CIRCULAR NUMBER: 9183 SUBJECT: GRB 090418A: Swift/UVOT Detection of the Neighbouring Galaxy DATE: 09/04/21 21:52:49 GMT FROM: Stephen Holland at USRA/NASA/GSFC/SSC S. T. Holland (CRESST/GSFC/USRA) reports on the behalf of the Swift UVOT team: Swift/UVOT observed the POSS2 galaxy (Pavlenko, et al., 2009, GCNC 9179) located approximately 4 arcsec northwest of the afterglow of GRB 090418A (Mangano, et al.,2009, GCNC 9149). We obtain the following preliminary magnitudes and 1-sigma errors for this galaxy. Filter Exposure Mag Err Sigma ------------------------------------- v 6163 21.0 0.2 5.5 b 4361 22.2 0.5 2.3 u 6057 21.3 0.2 5.6 uvw1 6178 21.6 0.2 4.7 uvm2 2109 21.5 0.4 2.9 uvw2 1357 21.3 0.3 3.4 ------------------------------------- Exposure is the total exposure time in seconds. The quoted magnitudes have not been corrected for the expected Galactic extinction along the line of sight corresponding to a reddening of E_{B-V} = 0.04 mag (Schlegel, et al., 1998, ApJS, 500, 525). All photometry is on the UVOT photometric system described in Poole et al. (2008, MNRAS, 383, 627). The detection of the galaxy in the uvw2 filter suggests that the galaxy has a redshift of less than approximately 1.3. The redshift of the afterglow is at least z = 1.608 (Chornock, et al., 2009, GCNC 9151). Therefore, we conclude that this galaxy is unlikely to be the host galaxy of GRB 090418A, in agreement with Pavlenko, et al. (2009, GCNC 9179).
GCN 9190 table
GRB_name GRB090418A
GCN_number 9190
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 9190 SUBJECT: GRB 090418A: RTT150 optical observations DATE: 09/04/22 11:07:11 GMT FROM: Rodion Burenin at IKI, Moscow I. Bikmaev, R.Zhuchkov, N. Sakhibullin (KSU/AST), I. Khamitov, Z. Eker (TUG), U. Kiziloglu (METU), E. Gogus (Sabanci Uni.), R. Burenin, M. Pavlinsky, R. Sunyaev (IKI) report: The optical afterglow of GRB 090418A (Chornock et al., GCN 9148, Mangano et al., GCN 9149) was observed with Russian-Turkish 1.5-m telescope (RTT150, Bakirlitepe, TUBITAK National Observatory, Turkey) under moderate transparences. We obtained series of 600s exposures in BVRc filters, centered at April 18, 23:40 UT, i.e. 0.52 days after the burst. The afterglow is clearly seen at combined R image, and marginally detected at combined B,V frames. Using the same calibration star USNO-B1.0 1234-0288651 as Pavlenko et al. (GCN 9179), we estimate the following magnitudes of OT: Filter, Exposure, mag., err. (s) B 3x600 23.5 limit V 3x600 22.7 limit R 4x600 22.1 +/- 0.1 We made also series of 3x900 sec exposures in Rc filter centered on April 20, 23:00, i.e. 2.5 days after the burst. The afterglow was not detected on the combined frame with a limit R=23.3 mag RTT150 finding chart (Rc) can be found at: http://hea.iki.rssi.ru/grb/090418a/indexeng.html
GCN 9196 table
GRB_name GRB090418A
GCN_number 9196
Detection_method Konus-Wind Det
Circular_text TITLE: GCN CIRCULAR NUMBER: 9196 SUBJECT: GRB 090418A: Konus-Wind and Swift/BAT joint spectral analysis DATE: 09/04/22 20:08:42 GMT FROM: Valentin Pal'shin at Ioffe Inst V. Pal'shin, S. Golenetskii, R.Aptekar, E. Mazets, D. Frederiks, and T. Cline on behalf of the Konus-Wind team, T. Sakamoto (GSFC/UMBC), S. D. Barthelmy (GSFC), W. Baumgartner (GSFC/UMBC), A. P. Beardmore (U Leicester), J. Cummings (GSFC/UMBC), E. Fenimore (LANL), N. Gehrels (GSFC), H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), K. McLean (GSFC/UMD), D. Palmer (LANL), G. Sato (GSFC/ISAS), M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC), and T. Ukwatta (GWU) on behalf of the Swift-BAT team, report: We performed the Konus-Wind and the Swift/BAT joint spectral analysis of GRB 090418A (Swift/BAT trigger #349510: Mangano et al., GCN Circ. 9149, Fenimore et al. GCN Circ. 9157). Since the Konus-Wind observed this GRB in the waiting mode, we only have 3 channel spectral data for the Konus-Wind which cover the energy range from 20 keV to 1.2 MeV. Therefore, the joint spectral analysis of the Konus-Wind and the Swift/BAT data enables to derive the broad-band spectral parameters of this burst. The time interval of the spectral data for each instrument is chosen from T0(BAT)-6.7 to T0(BAT)+58.1 sec where T0(BAT) is the trigger time of BAT at 11:07:40.2 UTC. The energy ranges which we used in the joint spectral analysis are 20-1200 keV and 14-150 keV for the Konus-Wind and the Swift/BAT respectively. The spectral data of two instruments are fitted with the spectral model multiplied by the constant factor to take into account the systematic effective area uncertainties in the response matrices of each instrument. The spectrum is well fitted with a power-law with exponential cutoff model: dN/dE ~ E^{alpha}*exp(-(2+alpha)*E/Epeak). The constant factors of each instrument agree within 20%. No systematic residual from the best fit model is seen in the spectral data of each instrument. The best fit spectral parameters are: alpha = -1.30 +/- 0.09 and Epeak = 610(-164, +530) keV (chi2/dof = 37.0/57). The best fit spectral parameters for the GRB (Band) model fixing beta = -2.5 are: alpha = -1.30 +/- 0.09, and Epeak = 601(-215, +554) keV (chi2/dof = 37.1/57). The energy fluence in the 15-1200 keV band calculated by a power-law with exponential cutoff model for this 64.8 sec interval is (1.79 +/- 0.21)x10^-5 erg/cm2. All the quoted errors are at the 90% confidence level. Assuming z = 1.6 (Chornock et al., GCN Circ. 9151) and a standard cosmology model with H_0 = 71 km/s/Mpc, Omega_M = 0.27, Omega_Lambda = 0.73, the isotropic energy release is E_iso ~2x10^53 erg in 1 keV to 10 MeV at the GRB rest frame extrapolating the best Band function fit fixing beta = -2.5. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB090418A/
GCN 9199 table
GRB_name GRB090418A
GCN_number 9199
Detection_method Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 9199 SUBJECT: GRB 090418A: R and I band observation DATE: 09/04/23 08:36:23 GMT FROM: Rupak Roy at ARIES Brajesh Kumar, Rupak Roy, Brijesh Kumar and S. B. Pandey (ARIES, NainiTal, India, on behalf of larger Indian GRB collaboration). We have imaged the field of swift GRB 090418A (GCN 9149) with the 104 cm Sampurnanand Optical telescope at ARIES Nainital on 18th April 2009 at 19.815 hrs UT. We do not detect any afterglow candidate in our co-added R_c and I_c band images (exp time 1400sec in each band) within the error circle of XRT (GCN 9163). The Photometry of the co-added frames put a 3 sigma upper limit of R ~ 20.64 and I ~ 19.65 mag in comparison to the nearby USNO - B1 stars.
GCN 9211 table
GRB_name GRB090418A
GCN_number 9211
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 9211 SUBJECT: GRB090418A Rc-band photometry DATE: 09/04/23 19:03:44 GMT FROM: Arne A. Henden at AAVSO A. Henden (AAVSO), J. Gross (SRO), B. Denny (DC-3), D. Terrell (SwRI), and W. Cooney (SRO) report: We obtained photometry of the GRB090418A afterglow reported by Chornock et al. (GCN 9148) using the Sonoita Research Observatory (SRO) 35cm telescope in southern Arizona, utilizing an automatic VOevent trigger. The Rc-band exposures began about 2 minutes after the burst and continued until twilight. Ten 60-second and five 180-second exposures were acquired. Astrometry of the afterglow from several images and using UCAC as the reference catalog yields coordinates: 17:57:15.151 +33:24:20.93 J2000 (+/- 50mas) Photometry, assuming that the star at 17:57:42.53 +33:25:47.2 has an R magnitude of 13.12 UT(mid) delT exp Rc err 11.1728 162 60 15.802 0.044 11.1919 231 60 16.185 0.048 11.2111 300 60 16.500 0.043 11.2303 369 60 16.818 0.058 11.2494 438 60 17.019 0.066 11.2686 507 60 17.249 0.067 11.2878 576 60 17.440 0.063 11.3069 645 60 17.605 0.105 11.3261 714 60 17.680 0.089 11.3450 782 60 17.855 0.115 11.3958 965 180 18.007 0.104 11.6522 1888 180 18.778 0.129 11.7067 2084 180 18.919 0.138 11.7592 2273 180 18.960 0.142 11.8114 2461 180 18.891 0.196 Where delT is the time in seconds from the burst (Mangano et al., GCN 9149), and the exposure is in seconds. The optical afterglow candidate is in the filter reflection halo from HD163948, a 6.9mag star about 2arcmin distant, so the last few magnitudes may have a systematic bias. We note that this field was not calibrated by SDSS through DR6. We will perform a BVRI calibration over the next few nights.
GCN 9293 table
GRB_name GRB090418A
GCN_number 9293
Detection_method Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 9293 SUBJECT: GRB 090418A BVRcIc field calibration DATE: 09/04/29 14:49:54 GMT FROM: Arne A. Henden at AAVSO A. Henden (AAVSO), J. Gross (SRO), B. Denny (DC-3), D. Terrell (SwRI), and W. Cooney (SRO) report: We have performed an all-sky calibration of the field for the GRB090418A afterglow reported by Chornock, et al. (GCN 9148) using the Sonoita Research Observatory (SRO) 35cm telescope in southern Arizona. Two photometric nights were used for the calibration, with multiple Landolt fields observed during each night along with an extinction star for the calibration. The calibration file has a limiting magnitude around V=18, with good standards brighter than V=16. The file is available at ftp://ftp.aavso.org/public/calib/grb/grb090418a.dat We estimate the external zeropoint error of this calibration to be about 0.02mag. In particular, the star used by Henden, et al. (GCN 9211) as a comparison star: 17:57:42.53 +33:25:47.2 J2000 has an R magnitude of 12.82, so all of the photometry in GCN 9211 should be adjusted 0.30mag brighter. Our system is available for any other bright UBVRI calibrations (4
GCN 9329 table
GRB_name GRB090418A
GCN_number 9329
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 9329 SUBJECT: GRB 090418A: optical observation DATE: 09/05/09 20:15:43 GMT FROM: Alexei Pozanenko at IKI, Moscow V. Rumyantsev, E. Pavlenko(CrAO), A. Pozanenko (IKI) report on behalf of larger GRB follow-up collaboration: We observed the afterglow of the Swift GRB 090418A (Mangano et al., GCN 9149) in I-filter on Apr. 20 (UT) 02:34:12 - 04:08:27 and in R-filter on Apr. 20 (UT) 21:03:05 - 22:49:20 with Shajn telescope of CrAO. We clearly detect afterglow in both epochs in stacked images. Preliminary photometry of Apr. 20 as well a photometry in V-filter of Apr. 18 observations (Pavlenko et al. GCN 9179) is following: T0+ Filter, Exposure, mag., err. UL Seeing (d) (s) 0.5476 V 17x60 22.3 +/- 0.2 23.2 1.9" 2.4507 R 70x60 22.8 +/- 0.1 24.4 1.9" Due to worse seeing (2.4") on Apr. 20 (UT) 02:34:12 - 04:08:27 the afterglow is evidently contaminated with nearby galaxy and photometry will be reported later. The photometry of Apr. 20 (UT) 21:03:05 - 22:49:20 also should be treated with caution due to possible contamination.