GRB150120B

This page lists all entries on GRB150120B in GRBweb

Summary IPN Swift GCN 17314 GCN 17315 GCN 17316 GCN 17320 GCN 17325 GCN 17330 GCN 17331 GCN 17335 GCN 17336 GCN 17337 GCN 17338 GCN 17339 GCN 17340 GCN 17343 GCN 17347 GCN 17366 GCN 17651

Summary table
Variable Value Source
T0 7:21:55 UTC GCN_circulars,Swift Det
ra 39.2907° Swift
decl 8.0779° Swift
pos_error 1.81e-04° Swift
T90 24.3 s Swift
T90_start 7:21:55 UTC Swift
fluence 5.40e-07 erg/cm² Swift
redshift 3.5000 GCN_circulars,GROND
T100 24.3 s
GBM_located False
mjd 57042.30688657407 GCN_circulars,Swift Det
IPN table
GRB_name GRB150120B
ra 39.2958°
decl 8.0833°
pos_error 5.00e-02°
Swift table
GRB_name GRB150120B
t_trigger 7:21:55 UTC
ra 39.2907°
decl 8.0779°
pos_error 1.81e-04°
T90 24.3 s
fluence 5.40e-07 erg/cm²
GCN 17314 table
GRB_name GRB150120B
GCN_number 17314
Detection_method Swift Det
t_trigger 7:21:55 UTC
ra 39.2940°
decl 8.0790°
Circular_text TITLE: GCN CIRCULAR NUMBER: 17314 SUBJECT: GRB 150120B: Swift detection of a burst DATE: 15/01/20 07:51:54 GMT FROM: David Palmer at LANL V. D'Elia (ASDC), L. Izzo (URoma/ICRA), N. P. M. Kuin (UCL-MSSL), A. Y. Lien (GSFC/UMBC), K. L. Page (U Leicester), D. M. Palmer (LANL) and M. H. Siegel (PSU) report on behalf of the Swift Team: At 07:21:55 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 150120B (trigger=627170). Swift slewed to this burst after a short delay due the Earth limb constraint. The BAT on-board calculated location is RA, Dec 39.294, +8.079 which is RA(J2000) = 02h 37m 11s Dec(J2000) = +08d 04' 43" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a complex structure with a duration of about 30 sec. The peak count rate was ~1000 counts/sec (15-350 keV), at ~2 sec after the trigger. The XRT began observing the field at 07:29:01.2 UT, 425.7 seconds after the BAT trigger. The position determined from promptly downlinked data differs significantly from the on-board position, suggesting that the XRT may have centroided on a cosmic ray; the initial XRT position notice should be treated with caution. Using promptly downlinked data we find an uncatalogued X-ray source with an enhanced position: RA, Dec 39.2927, 8.0781 which is equivalent to: RA(J2000) = 02h 37m 10.25s Dec(J2000) = +08d 04' 41.2" with an uncertainty of 2.7 arcseconds (radius, 90% containment). This location is 5.7 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. We cannot determine whether the source is fading at the present time. A power-law fit to a spectrum formed from promptly downlinked event data gives a column density consistent with the Galactic value of 1.16 x 10^21 cm^-2 (Willingale et al. 2013). UVOT took a finding chart exposure of 150 seconds with the White filter starting 432 seconds after the BAT trigger. No credible afterglow candidate has been found in the initial data products. The 2.7'x2.7' sub-image covers none of the XRT error circle. The 8'x8' region for the list of sources generated on-board covers 100% of the XRT error circle. The list of sources is typically complete to about 18 mag. No correction has been made for the expected extinction corresponding to E(B-V) of 0.20. Burst Advocate for this burst is V. D'Elia (delia AT asdc.asi.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 17315 table
GRB_name GRB150120B
GCN_number 17315
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 17315 SUBJECT: GRB 150120B: P60 optical afterglow DATE: 15/01/20 08:11:39 GMT FROM: Daniel Perley at Caltech D. A. Perley (Caltech) reports on behalf of a larger collaboration: The Palomar 60-inch robotic telescope began automatic follow-up of the location of GRB 150120B (D'Elia et al., GCN 17314) starting at 07:26:07 UT on 2015-01-20. In the first three 60-second frames (r, i, and z-bands) we detect a bright (r~18.7 mag), new source at the following location (J2000): RA = 02:37:09.770 dec = +08:04:40.37 After these three frames, the telescope received the initial XRT position notice and it executed a large slew to a new position, and this optical source was no longer in the field of view. It returned to the field with the updated XRT position notice in an image starting at 07:47:47; the GRB afterglow shows significant fading (to r~19.7 mag) in this observation since the first epoch, confirming it as the optical afterglow. We also note that the optical position above is near, but significantly outside (7 arcsec west) of, the updated XRT position given in GCN 17314. [GCN OPS NOTE(20jan15): Per author's request, the GRB name in the Subject-line was changed from 140120B to 150120B.]
GCN 17316 table
GRB_name GRB150120B
GCN_number 17316
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 17316 SUBJECT: GRB 150120B: FTN optical afterglow confirmation DATE: 15/01/20 08:44:28 GMT FROM: Cristiano Guidorzi at Ferrara U,Italy C. Guidorzi, S. Dichiara (U. Ferrara), C.G. Mundell (LJMU), A. Gomboc (U. Ljubljana) on behalf of a larger collaboration report: The 2-m Faulkes Telescope North began observing Swift GRB150120B (D'Elia et al. GCN 17314) on Jan 20 at 07:39:45 UT (~18 minutes after the burst trigger) with SDSS r and i filters. We clearly detect the optical candidate reported by Perley (GCN 17315), with a magnitude of r=19.21 +- 0.07 calibrated against nearby USNOB-1 (R1) stars.
GCN 17320 table
GRB_name GRB150120B
GCN_number 17320
Detection_method Swift-XRT Det
ra 39.2907°
decl 8.0779°
Circular_text TITLE: GCN CIRCULAR NUMBER: 17320 SUBJECT: GRB 150120B: Enhanced Swift-XRT position DATE: 15/01/20 15:06:41 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 5081 s of XRT Photon Counting mode data and 8 UVOT images for GRB 150120B, 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 = 39.29070, +8.07795 which is equivalent to: RA (J2000): 02h 37m 9.77s Dec (J2000): +08d 04' 40.6" with an uncertainty of 1.4 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, MNRAS, 397, 1177). This circular was automatically generated, and is an official product of the Swift-XRT team.
GCN 17325 table
GRB_name GRB150120B
GCN_number 17325
Detection_method Swift-XRT Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 17325 SUBJECT: GRB 150120B: Swift-XRT refined Analysis DATE: 15/01/20 20:51:04 GMT FROM: Phil Evans at U of Leicester J.A. Kennea (PSU), B.P. Gompertz (U. Leicester), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), M. de Pasquale (INAF-IASFPA), A. Maselli (INAF-IASFPA), A. Melandri (INAF-OAB), V. Mangano (PSU), M.C. Stroh (PSU) and V. D'Elia report on behalf of the Swift-XRT team: We have analysed 9.0 ks of XRT data for GRB 150120B (D'Elia et al. GCN Circ. 17314), from 438 s to 19.9 ks after the BAT trigger. The data are entirely in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Goad et al. (GCN Circ. 17320). The light curve can be modelled with a power-law decay with a decay index of alpha=0.91 (+/-0.05). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.97 (+0.14, -0.15). The best-fitting absorption column is 3.2 (+0.7, -0.8) x 10^21 cm^-2, in excess of the Galactic value of 1.2 x 10^21 cm^-2 (Willingale et al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.8 x 10^-11 (5.6 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 3.2 (+0.7, -0.8) x 10^21 cm^-2 Galactic foreground: 1.2 x 10^21 cm^-2 Excess significance: 4.5 sigma Photon index: 1.97 (+0.14, -0.15) If the light curve continues to decay with a power-law decay index of 0.91, the count rate at T+24 hours will be 6.7 x 10^-3 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 2.6 x 10^-13 (3.8 x 10^-13) erg cm^-2 s^-1. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00627170. This circular is an official product of the Swift-XRT team.
GCN 17330 table
GRB_name GRB150120B
GCN_number 17330
Detection_method Swift-BAT Det
ra 39.3090°
decl 8.0640°
Circular_text TITLE: GCN CIRCULAR NUMBER: 17330 SUBJECT: GRB 150120B: Swift-BAT refined analysis DATE: 15/01/20 22:51:16 GMT FROM: Amy Lien at GSFC C. B. Markwardt (GSFC), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC), V. D'Elia (ASDC) N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), A. Y. Lien (GSFC/UMBC), D. M. Palmer (LANL), T. Sakamoto (AGU), M. Stamatikos (OSU), J. Tueller (GSFC), T. N. Ukwatta (LANL) (i.e. the Swift-BAT team): Using the data set from T-61 to T+242 sec from the recent telemetry downlink, we report further analysis of BAT GRB 150120B (trigger #627170) (V. D'Elia, et al., GCN Circ. 17314). The BAT ground-calculated position is RA, Dec = 39.309, 8.064 deg which is RA(J2000) = 02h 37m 14.1s Dec(J2000) = +08d 03' 50.3" with an uncertainty of 2.3 arcmin, (radius, sys+stat, 90% containment). The partial coding was 35%. The mask-weighted light curve shows a multi-peaked structure starts at ~ T-20 s and ends at ~ T+10 s, with the main peak at ~ T+0 s. T90 (15-350 keV) is 24.30 +- 3.39 sec (estimated error including systematics). The time-averaged spectrum from T-17.64 to T+9.63 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 2.20 +- 0.25. The fluence in the 15-150 keV band is 5.4 +- 0.8 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T+0.58 sec in the 15-150 keV band is 1.2 +- 0.2 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/627170/BA/
GCN 17331 table
GRB_name GRB150120B
GCN_number 17331
Detection_method MITSuME
Circular_text TITLE: GCN CIRCULAR NUMBER: 17331 SUBJECT: GRB 150120B: MITSuME Okayama upper limits DATE: 15/01/21 01:24:44 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 MITSuME and OISTER collaboration: We observed the field of GRB 150120B (D'Elia et al., GCNC 17314) 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 2015-01-20 11:12:04 UT (~3.8 h after the burst). We could not detect the previously reported afterglow (Perley, GCNC 17315; Guidorzi et al., GCNC 17316) in all the three bands. Three sigma upper limits of the OT are listed below. We used GSC2.3 catalog for flux calibration. #T0+[day] MID-UT T-EXP[sec] g' Rc Ic ----------------------------------------------------- 0.20162 12:12:15 5760.0 >19.6 >19.6 >19.1 ----------------------------------------------------- T0+ : Elapsed time after the burst [day] T-EXP: Total Exposure time [sec]
GCN 17335 table
GRB_name GRB150120B
GCN_number 17335
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 17335 SUBJECT: GRB 150120B: Additional P60 observations DATE: 15/01/21 03:32:27 GMT FROM: Daniel Perley at Caltech D. A. Perley (Caltech) and S. B. Cenko (NASA/GSFC) report: We obtained further observations at the position of the optical afterglow (Perley, GCN 17315) of GRB 150120B (D'Elia et al., GCN 17314) with the Palomar 60-inch robotic telescope on the night of 2015-01-21 UT. In a combined stack of five 300-second r-band exposures we no longer detect any significant emission at the location of the optical afterglow. We estimate a limiting magnitude of r>22.7 mag (3 sigma) at a mid-time of 02:32:27 UT, t=0.799 days after the GRB. Relative to our previous observations, this suggests a decay power-law slope of at least alpha>0.75.
GCN 17336 table
GRB_name GRB150120B
GCN_number 17336
Detection_method GROND
ra 39.2907°
decl 8.0779°
redshift 3.5000
Circular_text TITLE: GCN CIRCULAR NUMBER: 17336 SUBJECT: GRB 150120B: GROND Afterglow Detection DATE: 15/01/21 09:14:34 GMT FROM: Philip Wiseman at MPE/Swift P Wiseman, J Graham, P Schady and J Greiner (All MPE Garching) report on behalf of the GROND team: We observed the field of GRB 150120B (Swift trigger 627170; D'Elia et al., GCN 17314) simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008, PASP 120, 405) mounted at the 2.2 m MPG telescope at ESO La Silla Observatory (Chile). Observations started at 01:25 UT on 21.01.2015, ~18hrs after the GRB trigger. They were performed at an average seeing of 1.1" and at an average airmass of 1.7. We find a single point source within the 1.4" Swift-XRT error circle (Goad et al., GCN 17320), consistent with that reported by Perley et al. (GCN 17315), Guidorzi et al. (GCN 17316), at RA (J2000) = 02 h 37 m 09.77 s DEC (J2000) = +08d 04' 40.49" with an uncertainty of 0.3" in each coordinate. Based on 25 min of total exposures in g'r'i'z'JHK, we estimate preliminary magnitudes and 3 sigma upper limits (all in AB system) of g' > 24.2 r' = 23.6 +/- 0.1 mag, i' = 22.7 +/- 0.2 mag, z' = 22.4 +/- 0.40 mag, J = 20.2 +/- 0.3 mag, H = 19.9 +/- 0.5 mag, and K = 18.7 +/- 0.4 mag. Based on these magnitudes, the best-fit SED has a break in the g' band suggesting a photometric redshift of 3.5 +/-0.5. Given magnitudes are calibrated against GROND zeropoints as well as 2MASS field stars and are not corrected for the expected Galactic foreground extinction corresponding to a reddening of E_(B-V)=0.17 mag in the direction of the burst (Schlegel et al. 1998).
GCN 17337 table
GRB_name GRB150120B
GCN_number 17337
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 17337 SUBJECT: GRB 150120B, Optical observations DATE: 15/01/21 12:02:24 GMT FROM: Shashi Bhushan Pandey at ROTSE S. B. Pandey (ARIES Nainital India, on behalf of larger Indian GRB collaboration) The 1.04m Sampurnanand telescope at ARIES Nainital began observations of the Swift-detected GRB 150120B (D'Elia et al., GCN 17314) starting at 13:34:44 UT on 2015-01-20. Several frames in R_c pass-band 300sec each were acquired in poor sky conditions. In the co-added image (6x300 sec), we detect the optical afterglow candidate at R_c ~ 21.7+-0.1 mag to the location consistent with that reported by Perley et al. (GCN 17315), Guidorzi et al. (GCN 17316). The temporal power-law flux decay seems to follow an index of 0.7 at the epoch of our observations as reported by Perley & Cenko (GCN 17335). The photometry was performed in comparison to nearby USNO- B1 stars. This massage may be cited.
GCN 17338 table
GRB_name GRB150120B
GCN_number 17338
Detection_method Swift-UVOT Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 17338 SUBJECT: GRB 150120B: Swift/UVOT Upper Limits DATE: 15/01/21 13:36:09 GMT FROM: Margaret Chester at PSU GRB 150120B: Swift/UVOT Upper Limits M. M. Chester (PSU) and V. D'Elia (ASDC) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 150120B 432 s after the BAT trigger (D'Elia et al., GCN Circ. 17314). No source consistent with the optical afterglow reported by Perley (GCN Circ. 17315) and Guidorzi et al. (GCN Circ. 17316) is detected in the initial UVOT exposures. Preliminary 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first finding chart (FC) exposure and subsequent exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag white_FC 432 582 147 >19.9 white 432 1014 295 >20.5 white 7279 7479 197 >20.7 v 6254 19560 1278 >20.1 b 7074 25878 979 >20.9 u 6869 25353 1999 >21.0 w1 639 2670 214 >19.6 w1 6664 24440 2164 >21.0 m2 6459 20294 1996 >21.0 w2 1885 3036 124 >19.5 w2 7484 18646 1082 >20.8 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.20 in the direction of the burst (Schlegel et al. 1998).
GCN 17339 table
GRB_name GRB150120B
GCN_number 17339
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 17339 SUBJECT: GRB150120B: Xinglong TNT optical observation DATE: 15/01/21 14:07:31 GMT FROM: L.P. Xin at NAOC L. P. Xin, X. F. Wang, J. Y. Wei, Y. L. Qiu, J. S. Deng, J. Wang, X. H. Han and C. Wu on behalf of EAFON report: We began to observe GRB 150120B (D'Elia et al., GCN 17314) with Xinglong 0.8-m TNT telescope at 2015-01-20, 10:56:50 (UT), about 3.58 hours after the burst. In the 15*300sec coadded R-bamd image, the optical counterpart (D. A. Perley GCN 17315; Guidorzi et al., GCN 17316; Wiseman et al., 17336; Pandey GCN 17337) was detected with a brightness of R=21.3+/-0.2 mag at the mid-time of 4.2 hours after the burst, calibrated by the nearby USNO B1.0 R2 mag. The message may be cited.
GCN 17340 table
GRB_name GRB150120B
GCN_number 17340
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 17340 SUBJECT: GRB 150120B: FTN early optical light curve DATE: 15/01/21 14:51:41 GMT FROM: Cristiano Guidorzi at Ferrara U,Italy C. Guidorzi, S. Dichiara (U. Ferrara), C.G. Mundell (LJMU), A. Gomboc (U. Ljubljana) on behalf of a large collaboration report: The 2-m Faulkes Telescope North observed Swift GRB150120B (D'Elia et al. GCN 17314; Perley GCN 17315) from 18 to 100 minutes since the burst trigger time with SDSS r and i filters. Both light curves are fitted with a power-law with a decay index alpha=0.8 +- 0.1. A comparison with the observations at later times (Perley GCN 17335; Wiseman et al. GCN 17336; Pandey GCN 17337; Xin et al. GCN 17339) suggests that a steepening of the decay must have occurred between ~2e4 and ~6e4 s.
GCN 17343 table
GRB_name GRB150120B
GCN_number 17343
Detection_method Swift-BAT Det
Circular_text TITLE: GCN CIRCULAR NUMBER: 17343 SUBJECT: GRB 150120B: RATIR Optical and NIR Observations DATE: 15/01/21 21:24:35 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 (ORAU/GSFC), 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 150120B (D'Elia, et al., GCN 17314) 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 2015/01 21.09 to 2015/01 21.29 UTC (18.73 to 23.64 hours after the BAT trigger), obtaining a total of 3.91 hours exposure in the r, i, and z bands. For a source coincident with the GROND optical transient (Wiseman et al., GCN 17336), in comparison with 2MASS, we obtain the following detections and upper limit (3-sigma): r = 23.4 +/- 0.2 i = 22.6 +/- 0.1 z > 20.72 These magnitudes are in the AB system and 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 17347 table
GRB_name GRB150120B
GCN_number 17347
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 17347 SUBJECT: GRB 150120B: Mondy optical observations DATE: 15/01/23 19:00:55 GMT FROM: Alexei Pozanenko at IKI, Moscow E. Mazaeva (IKI), A. Volnova (IKI), E. Klunko (ISTP), I. Korobtsev (ISTP), M. Eselevich (ISTP), A. Pozanenko (IKI) report on behalf of larger GRB follow-up collaboration: We observed the field of GRB 150120B (D'Elia et al., GCN 17314) with AZT-33IK telescope of Sayan observatory (Mondy) Jan., 20 starting on (UT) 11:42:02. We obtained 65 images in R-filter of 120 s exposure. In two combined images within enhanced Swift-XRT error circle (Goad et al., GCN 17320) we clearly detect optical afterglow (Perley et al. GCN 17315, Guidorzi et al. GCN 17316). Photometry of the afterglow is following Date UT start t-T0 Filter Exp. OT Err. (mid, days) (s) 2015-01-20 11:42:02 0.20149 R 30*120 21.25 0.22 2015-01-20 12:42:04 0.24348 R 30*120 21.43 0.25 Photometry is based on nearby USNO B1.0 (R2) stars: USNO-B1.0_id R 0980-0031064 15.57 0980-0031070 14.16 0980-0031080 16.35 0980-0031095 15.41
GCN 17366 table
GRB_name GRB150120B
GCN_number 17366
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 17366 SUBJECT: GRB 150120B: Khureltogot optical observations DATE: 15/01/30 21:25:11 GMT FROM: Alexei Pozanenko at IKI, Moscow E. Mazaeva (IKI), S. Schmalz (AIP), N. Tungalag (Research Center of Astronomy and Geophysics MAS), A. Volnova (IKI), I.Molotov (KIAM), A. Pozanenko (IKI) report on behalf of larger GRB follow-up collaboration: We observed the field of GRB 150120B (D'Elia et al., GCN 17314) with ORI-40 telescope of Khureltogot observatory on Jan., 20 starting on (UT) 10:52:51. We obtained 90 unfiltered images of 60 s exposure. Within enhanced Swift-XRT error circle (Goad et al., GCN 17320) we clearly detect optical afterglow (Perley et al. GCN 17315, Guidorzi et al. GCN 17316) in a combined image. Photometry of the afterglow is following Date UT start t-T0 Filter Exp. OT OT_err (mid, days) (s) 2015-01-20 10:52:51 0.18068 none 90*60 20.75 0.20 The photometry is based on R magnitudes of nearby USNO-B1.0 stars USNO-B1_id R2 0981-0032639 16.04 0981-0032644 17.10
GCN 17651 table
GRB_name GRB150120B
GCN_number 17651
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 17651 SUBJECT: GRB 150120B: GMG observation DATE: 15/03/29 08:21:35 GMT FROM: Jirong Mao at Yunnan Obs J. Mao, J. Zhang, and J.-M. Bai (YNAO) report: We observed the field of GRB 150120B (D'Elia et al., GCN 17314) with the 2.4-meter optical telescope at Gao-Mei-Gu (GMG) station of Yunnan Observatory. Observations began from UT 13:42:43.5 20th, Jan., 2015 (about 6.3 hours after the trigger). We clearly detected the optical counterpart with brightness of R=22.1+/-0.1 mag. J. Mao apologizes for this very late GCN circular submission.