GRB170921A

This page lists all entries on GRB170921A in GRBweb

Summary IPN Swift GCN 21901 GCN 21903 GCN 21904 GCN 21905 GCN 21906 GCN 21907 GCN 21909 GCN 21910 GCN 21912 GCN 21913 GCN 21915 GCN 21951

Summary table
Variable Value Source
T0 14:28:48 UTC GCN_circulars,Swift Det
ra 26.8490° Swift
decl 30.9067° Swift
pos_error 1.94e-04° Swift
T90 28.9 s Swift
T90_start 14:28:48 UTC Swift
fluence 6.70e-07 erg/cm² Swift
T100 28.9 s
GBM_located False
mjd 58017.60333333333 GCN_circulars,Swift Det
IPN table
GRB_name GRB170921A
ra 26.8500°
decl 30.8667°
pos_error 5.00e-02°
Swift table
GRB_name GRB170921A
t_trigger 14:28:48 UTC
ra 26.8490°
decl 30.9067°
pos_error 1.94e-04°
T90 28.9 s
fluence 6.70e-07 erg/cm²
GCN 21901 table
GRB_name GRB170921A
GCN_number 21901
Detection_method Swift Det
t_trigger 14:28:48 UTC
ra 26.8490°
decl 30.8740°
Circular_text TITLE: GCN CIRCULAR NUMBER: 21901 SUBJECT: GRB 170921A: Swift detection of a burst DATE: 17/09/21 14:44:31 GMT FROM: Boris Sbarufatti at PSU A. D'Ai (INAF-IASFPA), V. D'Elia (ASDC), P. A. Evans (U Leicester), J.D. Gropp (PSU), J. A. Kennea (PSU), H. A. Krimm (NSF/USRA), S. J. LaPorte (PSU), F. E. Marshall (NASA/GSFC), K. L. Page (U Leicester), B. Sbarufatti (PSU) and M. H. Siegel (PSU) report on behalf of the Swift Team: At 14:28:48 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 170921A (trigger=773509). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 26.849, +30.874 which is RA(J2000) = 01h 47m 24s Dec(J2000) = +30d 52' 27" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a single-peaked structure with a duration of about 20 sec. The peak count rate was ~1000 counts/sec (15-350 keV), at ~5 sec after the trigger. The XRT began observing the field at 14:30:25.8 UT, 97.3 seconds after the BAT trigger. Using promptly downlinked data we find a fading, uncatalogued X-ray source with an enhanced position: RA, Dec 26.8484, 30.9069 which is equivalent to: RA(J2000) = 01h 47m 23.63s Dec(J2000) = +30d 54' 24.8" with an uncertainty of 2.2 arcseconds (radius, 90% containment). This location is 118 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 in excess of the Galactic value (5.49 x 10^20 cm^-2, Willingale et al. 2013), with an excess column of 1.4 (+0.67/-0.55) x 10^22 cm^-2 (90% confidence). UVOT took a finding chart exposure of 150 seconds with the White filter starting 100 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 0.05. Burst Advocate for this burst is A. D'Ai (antonino.dai 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 21903 table
GRB_name GRB170921A
GCN_number 21903
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 21903 SUBJECT: GRB 170921A: TAROT Calern observatory optical observations DATE: 17/09/21 19:35:55 GMT FROM: Alain Klotz at IRAP-CNRS-OMP Klotz A., Atteia J.L. (CNRS-OMP-IRAP), Boer, M., Laugier, R. (CNRS-ARTEMIS), Gendre B. (UVI - Etelman Obs.) report: We imaged the field of GRB 170921A detected by SWIFT (trigger 773509) with the TAROT robotic telescope (D=25cm) located at the Calern observatory, France. The observations started 3.86h after the GRB trigger. The elevation of the field increased from 12 degrees above horizon and weather conditions were good. We co-added a series of exposures. No OT is detected with a limiting magnitude of: t0+3.86h to t0+4.23h : Rlim = 19.5 Magnitudes were estimated with the nearby USNO-B1 stars and are not corrected for galactic dust extinction.
GCN 21904 table
GRB_name GRB170921A
GCN_number 21904
Detection_method Swift-XRT Other
ra 26.8487°
decl 30.9067°
Circular_text TITLE: GCN CIRCULAR NUMBER: 21904 SUBJECT: GRB 170921A: Swift-XRT refined Analysis DATE: 17/09/21 22:29:22 GMT FROM: Phil Evans at U of Leicester B. Sbarufatti (INAF-OAB/PSU), S.L. Gibson (U. Leicester), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), V. D'Elia (ASDC), A. Melandri (INAF-OAB), D.N. Burrows (PSU), A. Tohuvavohu (PSU) and A. D'Ai report on behalf of the Swift-XRT team: We have analysed 6.5 ks of XRT data for GRB 170921A (D'Ai et al. GCN Circ. 21901), from 82 s to 16.5 ks after the BAT trigger. The data comprise 8 s in Windowed Timing (WT) mode (taken while Swift was slewing), with the remainder in Photon Counting (PC) mode. The best available XRT position (using the promptly downlinked event data, the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue) is RA, Dec = 26.8487, 30.9067 which is equivalent to: RA (J2000): 01 47 23.70 Dec(J2000): +30 54 24.3 with an uncertainty of 2.1 arcsec (radius, 90% confidence). The light curve can be modelled with an initial power-law decay with an index of alpha=3.3 (+0.5, -0.4), followed by a break at T+238 s to an alpha of 0.85 (+0.10, -0.09). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 2.7 (+0.4, -0.3). The best-fitting absorption column is 1.00 (+0.27, -0.23) x 10^22 cm^-2, in excess of the Galactic value of 5.5 x 10^20 cm^-2 (Willingale et al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.5 x 10^-11 (1.2 x 10^-10) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 1.00 (+0.27, -0.23) x 10^22 cm^-2 Galactic foreground: 5.5 x 10^20 cm^-2 Excess significance: 6.7 sigma Photon index: 2.7 (+0.4, -0.3) If the light curve continues to decay with a power-law decay index of 0.85, the count rate at T+24 hours will be 2.1 x 10^-3 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 7.3 x 10^-14 (2.5 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/00773509. This circular is an official product of the Swift-XRT team.
GCN 21905 table
GRB_name GRB170921A
GCN_number 21905
Detection_method MITSuME
Circular_text TITLE: GCN CIRCULAR NUMBER: 21905 SUBJECT: GRB 170921A: MITSuME Okayama upper limits DATE: 17/09/21 22:40:42 GMT FROM: Daisuke Kuroda at OAO/NAOJ D. Kuroda, K. Yanagisawa, Y. Shimizu, H. Toda (OAO, NAOJ), S. Nagayama (NAOJ), M. Yoshida (Subaru, NAOJ), K. Ohta (Kyoto) and N. Kawai(Tokyo Tech) report on behalf of MITSuME collaboration: We observed the field of GRB 170921A (D'Ai et al., GCNC 21901) 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 2017-09-21 14:39:14 UT (~10 min after the burst). We did not find any new point source within the XRT error circle (D'Ai et al., GCNC 21901) in all the three bands. Three sigma upper limits of the OT are listed below. We used SDSS-DR8 catalog for flux calibration. #T0+[day] MID-UT T-EXP[sec] g' Rc Ic ----------------------------------------------------- 0.04269 15:30:16 5760.0 >20.1 >19.8 >18.8 ----------------------------------------------------- T0+ : Elapsed time after the burst [day] T-EXP: Total Exposure time [sec]
GCN 21906 table
GRB_name GRB170921A
GCN_number 21906
Detection_method Swift-XRT Det
ra 26.8491°
decl 30.9067°
Circular_text TITLE: GCN CIRCULAR NUMBER: 21906 SUBJECT: GRB 170921A: Enhanced Swift-XRT position DATE: 17/09/21 23:19:36 GMT FROM: Phil Evans at U of Leicester A.P. Beardmore, P.A. Evans, M.R. Goad and J.P. Osborne (U. Leicester) report on behalf of the Swift-XRT team. Using 2671 s of XRT Photon Counting mode data and 5 UVOT images for GRB 170921A, 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 = 26.84906, +30.90673 which is equivalent to: RA (J2000): 01h 47m 23.77s Dec (J2000): +30d 54' 24.2" with an uncertainty of 1.5 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 21907 table
GRB_name GRB170921A
GCN_number 21907
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 21907 SUBJECT: GRB 170921A: Nanshan optical upper limit DATE: 17/09/22 00:33:24 GMT FROM: Dong Xu at NAOC/CAS H.X. Feng (NAOC), Y.D. Hu (IAA-CSIC), D. Xu, Z.P. Zhu (NAOC), X. Zhang, T.Z. Yang, J.Z. Liu, A. Esamdin, L. Ma (XAO), Y. Qin (Geneva Obs.) report: We observed the field of long GRB 170921A (D'Ai et al., GCN 21901) using the 1m telescope located at Nanshan, Xinjiang, China. We obtained 3*180s R-band frames, starting at 15:52:35.04 UT on 2017-09-21 (i.e., 1.39 hr after the BATtrigger). No optical source is detected at the XRT position (Beardmore et al., GCN 21906) in the stacked image, down to a limiting magnitude of m(R)~20.3, calibrated with the USNO-B1 catalog.
GCN 21909 table
GRB_name GRB170921A
GCN_number 21909
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 21909 SUBJECT: GRB 170921A: NOT optical observations DATE: 17/09/22 07:23:28 GMT FROM: Daniele Malesani at Dark Cosmology Centre, Niels Bohr Inst D. Malesani (DARK/NBI), K. E. Heintz (Univ. Iceland and DARK/NBI), N. R. Tanvir (Univ. Leicester), D. A. Kann (IAA/CSIC), T. Pursimo (NOT), and S. Dyrbye (NOT) report on behalf of a larger collaboration: We observed the field of GRB 170921A (D'Ai et al., GCN 21901) with the Nordic Optical Telescope equipped with the AlFOSC imager. Observations were carried out with the SDSS r' and z' filters, for a total exposure of 900 and 1800 s, respectively. We did not detect any new object inside or in the proximity of the enhanced X-ray error circle (Beardmore et al., GCN 21906). At mean epochs 2017 Sep 21.941 and Sep 21.958 UT (8.1 and 8.5 hr after the GRB), we report 3-sigma limiting magnitudes r' > 24.3 and z' > 23.3, respectively (both AB, calibrated against the Pan-STARRS catalog). Our non-detections are consistent with the reports by TAROT (Klotz et al., GCN 21903), MITSuME (Kuroda et al., GCN 21905), and Nanshan (Feng et al., GCN 21907).
GCN 21910 table
GRB_name GRB170921A
GCN_number 21910
Detection_method Swift-XRT Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 21910 SUBJECT: GRB 170921A: LCO 2m telescope observations DATE: 17/09/22 12:07:33 GMT FROM: Cristiano Guidorzi at Ferrara U,Italy C. Guidorzi (U. Ferrara), S. Kobayashi (LJMU), C.G. Mundell (U. Bath), A. Gomboc (U. Nova Gorica), I.A. Steele (LJMU), A. Cucchiara, D. Morris, and B. Gendre (U. Virgin Islands) on behalf of a large collaboration report: We began observing Swift GRB 170921A (D'Ai et al. GCN 21901) on September 21, from 14:52 to 15:05 UT (from 24 to 37 minutes since the GRB trigger time) with the LCO 2-m telescope in Hawaii in the SDSS R and I filters. Within the enhanced Swift-XRT circle (Beardmore et al. GCN 21906) we do not detect any optical counterpart down to the following limits, in agreement with previous reports (Klotz et al. GCN 21903; Kuroda et al. GCN 21905; Feng et al. GCN 21907; Malesani et al. GCN 21909): Mid Time Exposure Filter Magnitude (AB) (min) (s) ------------------------------------------------------- 26.8 5x60 SDSS-R > 20.7 34.0 3x60 SDSS-I > 19.8 ------------------------------------------------------- as calibrated against nearby SDSS objects.
GCN 21912 table
GRB_name GRB170921A
GCN_number 21912
Detection_method Swift-BAT Det
ra 26.8400°
decl 30.8800°
Circular_text TITLE: GCN CIRCULAR NUMBER: 21912 SUBJECT: GRB 170921A: Swift-BAT refined analysis DATE: 17/09/22 14:27:15 GMT FROM: Amy Lien at GSFC T. Sakamoto (AGU), S. D. Barthelmy (GSFC), J. R. Cummings (CPI), A. D'Ai (INAF-IASFPA) H. A. Krimm (NSF/USRA), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), D. M. Palmer (LANL), M. Stamatikos (OSU), T. N. Ukwatta (LANL) (i.e. the Swift-BAT team): Using the data set from T-239 to T+963 sec from the recent telemetry downlink, we report further analysis of BAT GRB 170921A (trigger #773509) (D'Ai et al., GCN Circ. 21901). The BAT ground-calculated position is RA, Dec = 26.840, 30.880 deg which is RA(J2000) = 01h 47m 21.6s Dec(J2000) = +30d 52' 47.1" with an uncertainty of 1.8 arcmin, (radius, sys+stat, 90% containment). The partial coding was 86%. The mask-weighted light curve shows a single-peaked structure that starts at ~T-22 s, peaks at ~T+3 s, and ends at ~T+13 s. T90 (15-350 keV) is 28.9 +- 6.0 sec (estimated error including systematics). The time-averaged spectrum from T-21.82 to T+13.00 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.76 +- 0.17. The fluence in the 15-150 keV band is 6.7 +- 0.8 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T+2.74 sec in the 15-150 keV band is 0.8 +- 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/773509/BA/
GCN 21913 table
GRB_name GRB170921A
GCN_number 21913
Detection_method Swift-UVOT Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 21913 SUBJECT: GRB 170921A: Swift/UVOT Upper Limits DATE: 17/09/22 14:56:56 GMT FROM: Sam LaPorte at PSU GRB 170921A: Swift/UVOT Upper Limits S. J. LaPorte (PSU) and A. D'Ai (INAF-IASFPA) report on behalf of the Swift/UVOT team: (Beardmore et al. GCN Circ. 21906) The Swift/UVOT began settled observations of the field of GRB 170921A 101 s after the BAT trigger (D'Ai et al., GCN Circ. 21901). No optical afterglow consistent with the XRT position 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 101 251 147 >20.7 u_FC 259 509 246 >20.4 white 101 6816 766 >21.4 v 590 7186 451 >19.9 b 516 6611 471 >20.6 u 259 12926 1346 >21.1 w1 639 12273 1171 >20.6 m2 1412 11366 1102 >21.0 w2 566 16512 687 >21.0 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.05 in the direction of the burst (Schlegel et al. 1998).
GCN 21915 table
GRB_name GRB170921A
GCN_number 21915
Detection_method Swift-XRT Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 21915 SUBJECT: GRB 170921A: RATIR Optical Afterglow Detection and NIR Observations DATE: 17/09/22 23:22:09 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), Ori Fox (STScI), J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (UVI), Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico Ramirez-Ruiz (UCSC), Jesús González (UNAM), Carlos Román-Zúñiga (UNAM), Harvey Moseley (GSFC), John Capone (UMD), V. Zach Golkhou (ASU), and Vicki Toy (UMD) report: We observed the field of GRB 170921A (D'Ai, et al., GCN 21901) with the Reionization and Transients Infrared Camera (RATIR; www.ratir.org) on the 1.5m Harold Johnson Telescope at the Observatorio Astronómico Nacional on Sierra San Pedro Mártir from 2017/09 22.18 to 2017/09 22.51 UTC (13.82 to 21.76 hours after the BAT trigger), obtaining a total of 5.29 hours exposure in the r and i bands and 2.22 hours exposure in the Z, Y, J, and H bands. For a source within the Swift-XRT error circle (Beardmore, et al., GCN 21906), in comparison with the SDSS DR9 and 2MASS catalogs, we obtain the following weak detections and upper limits (3-sigma): r = 24.45 +/- 0.34 i = 24.38 +/- 0.34 Z > 23.05 Y > 22.83 J > 22.47 H > 22.19 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 Astronómico Nacional in San Pedro Mártir.
GCN 21951 table
GRB_name GRB170921A
GCN_number 21951
Detection_method Swift Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 21951 SUBJECT: GRB 170921A: 15 GHz upper limits from AMI DATE: 17/10/01 20:13:58 GMT FROM: Kunal Mooley at Oxford U K. P. Mooley (Hintze Fellow, Oxford), T. D. Staley, R. P. Fender (Oxford), G. E. Anderson (Curtin), T. Cantwell (Manchester), D. Titterington, S. H. Carey, J. Hickish, Y. C. Perrott, N. Razavi-Ghods, P. Scott (Cambridge), K. Grainge, A. Scaife (Manchester) The AMI Large Array robotically triggered on the Swift alert for GRB 170921A (D'Ai et al., GCN 21901) as part of the 4pisky program, and subsequent follow up observations were obtained up to 10 days post-burst. Our observations at 15 GHz on 2017 Sep 21.89, Sep 27.04 and Sep 28.97 (UT) do not reveal any radio source at the XRT location (Beardmore et al., GCN 21906), with 3sigma upper limits of 186 uJy, 117 uJy and 159 uJy respectively. We thank the AMI staff for scheduling these observations. The AMI-GRB database is a log of all GRB follow up observations with the AMI, and is available at http://4pisky.org/ami-grb/.