GRB250807A

This page lists all entries on GRB250807A in GRBweb

Summary IPN Swift GCN 41262 GCN 41270 GCN 41274 GCN 41281 GCN 41283 GCN 41290 GCN 41291 GCN 41295 GCN 41299

Summary table
Variable Value Source
T0 10:46:06.990 UTC GCN_circulars,Konus-Wind Det
ra 51.4483° Swift
decl -47.8878° Swift
pos_error 9.71e-05° Swift
GBM_located False
mjd 60894.44869201389 GCN_circulars,Konus-Wind Det
IPN table
GRB_name GRB250807A
ra 51.4208°
decl -47.8833°
pos_error 5.00e-02°
Swift table
GRB_name GRB250807A
t_trigger 10:46:08.440 UTC
ra 51.4483°
decl -47.8878°
pos_error 9.71e-05°
GCN 41262 table
GRB_name GRB250807A
GCN_number 41262
Detection_method Swift Det
t_trigger 10:46:08.440 UTC
ra 51.4200°
decl -47.8770°
Circular_text TITLE: GCN CIRCULAR NUMBER: 41262 SUBJECT: GRB 250807A: Swift detection of a burst with an optical counterpart DATE: 25/08/07 11:03:36 GMT FROM: noelklin@umbc.edu N. J. Klingler (GSFC/UMBC/CRESSTII), R. Brivio (INAF-OAB), J. J. DeLaunay (PSU), R. Gupta (NASA GSFC), J. A. Kennea (PSU), K. L. Page (U Leicester) and C. Salvaggio (INAF-OAB) report on behalf of the Neil Gehrels Swift Observatory Team: At 10:46:08.44 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 250807A (trigger=1340514). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 51.420, -47.877 which is RA(J2000) = 03h 25m 41s Dec(J2000) = -47d 52' 38" 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 80 sec. The peak count rate was ~19000 counts/sec (15-350 keV), at ~35 sec after the trigger. The XRT began observing the field at 10:47:49.5 UT, 101.1 seconds after the BAT trigger. XRT found a bright, uncatalogued X-ray source located at RA, Dec 51.4478, -47.8880 which is equivalent to: RA(J2000) = 03h 25m 47.47s Dec(J2000) = -47d 53' 16.8" with an uncertainty of 4.8 arcseconds (radius, 90% containment). This location is 77 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 111 seconds after the BAT trigger. There is a candidate afterglow in the rapidly available 2.7'x2.7' sub-image at RA(J2000) = 03:25:47.59 = 51.44829 DEC(J2000) = -47:53:16.2 = -47.88782 with a 90%-confidence error radius of about 0.75 arc sec. This position is 1.3 arc sec. from the center of the XRT error circle. The estimated magnitude is 17.98 with a 1-sigma error of about 0.14. No correction has been made for the expected extinction corresponding to E(B-V) of 0.011. Burst Advocate for this burst is N. J. Klingler (noelklin AT umbc.edu). 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/)
GCN 41270 table
GRB_name GRB250807A
GCN_number 41270
Detection_method Swift-XRT Det
ra 51.4479°
decl -47.8876°
Circular_text TITLE: GCN CIRCULAR NUMBER: 41270 SUBJECT: GRB 250807A: Enhanced Swift-XRT position DATE: 25/08/07 16:14:45 GMT FROM: Phil Evans at U of Leicester P.A. Evans, M.R. Goad, J.P. Osborne and A.P. Beardmore (U. Leicester) report on behalf of the Swift-XRT team. Using 769 s of XRT Photon Counting mode data and 3 UVOT images for GRB 250807A, 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 = 51.44795, -47.88761 which is equivalent to: RA (J2000): 03h 25m 47.51s Dec (J2000): -47d 53' 15.4" with an uncertainty of 2.0 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 41274 table
GRB_name GRB250807A
GCN_number 41274
Detection_method Optical
ra 51.4481°
decl -47.8877°
Circular_text TITLE: GCN CIRCULAR NUMBER: 41274 SUBJECT: GRB 250807A: SVOM/VT optical observation DATE: 25/08/08 03:38:37 GMT FROM: Yinuo Ma Y. N. Ma, Z. H. Yao, L. P. Xin, Y. L. Qiu, C. Wu, H. L. Li, X. H. Han, Y. Xu, J. Wang, P. P. Zhang, W. J. Xie, Y. J. Xiao, H. B. Cai, L. Lan, J. S. Deng, J. Y. Wei (NAOC), J. Palmerio (CEA) report on behalf of the SVOM/VT team. SVOM/VT performed a Target of Opportunity observation of GRB 250807A detected by Swift-BAT（Klingler et al., GCN 41262; Evans et al., GCN 41270). The observation began at 2025-08-07T11:21:39.516 UTC, 35.52 minutes after the trigger, in the VT_B (400nm-650nm) and VT_R (650nm-1000nm) channels simultaneously. The optical afterglow (Evans et al., GCN 41262) is detected in both VT_R and VT_B using VT X-band data at R.A. = 51.448126 , DEC = -47.887663 degrees: RA (J2000) = 3:25:47.55 Dec (J2000) = -47:53:15.58 with an uncertainty of 0.5 arcsec. The magnitudes are: mid time (sec) | exposure time (s) | band | mag (AB) | mag err ---------------|-------------------|------|----------|-------- 2236 | 70 | VT_B | 20.52 | 0.08 14319 | 70 | VT_B | 21.07 | 0.10 2236 | 70 | VT_R | 18.98 | 0.03 14319 | 70 | VT_R | 19.29 | 0.03 Our photometry was not corrected for Galactic extinction. During our observations, the light curves exhibit an initial brightening followed by a decay phase. The Space Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA, China), National Centre for Space Studies (CNES, France) and the Chinese Academy of Sciences (CAS, China), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. VT was jointly developed by Xi'an Institute of Optics and Precision Mechanics (XIOPM), CAS and National astronomical observatories (NAOC), CAS.
GCN 41281 table
GRB_name GRB250807A
GCN_number 41281
Detection_method AstroSat CZTI
Circular_text TITLE: GCN CIRCULAR NUMBER: 41281 SUBJECT: GRB 250807A: AstroSat CZTI detection of bright long burst DATE: 25/08/08 09:48:16 GMT FROM: Gaurav Waratkar at IIT Bombay S.Salunke (IUCAA), G. Waratkar (IITB), A. Vibhute (IUCAA), V. Bhalerao (IITB), D. Bhattacharya (Ashoka University/IUCAA), A. R. Rao (IUCAA/TIFR), and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration: Analysis of AstroSat CZTI data with the CIFT framework (Sharma et al., 2021, JApA, 42, 73) showed the detection of a bright long-duration GRB 250807A which was also detected by Swift/BAT (N. J. Klingler et.al, GCN Circ. 41262), and Konus-Wind (reported through GCN Notices). The source was clearly detected in the CZT detectors in the 20-200 keV energy range. The light curve showed multiple peaks of emission with the strongest peak at 2025-08-07 10:46:42.50 UTC. The measured peak count rate associated with the burst is 535 (+49, -47) counts/s above the background in the combined data of all quadrants, with a total of 6218 (+449, -269) counts. The local mean background count rate was 275 (+1, -4) counts/s. Using cumulative rates, we measure a T90 of 44 (+2, -3) s. In the preliminary analysis, we find 630 Compton events associated with this event. The source was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve showed multiple peaks of emission with the strongest peak at 2025-08-07 10:46:42.27 UTC. The measured peak count rate associated with the burst is 3662 (+110, -125) counts/s above the background in the combined data of all quadrants, with a total of 36237 (+1153, -1203) counts. The local mean background count rate was 1239 (+5, -6) counts/s. We measure a T90 of 48 (+1, -3) s from the cumulative Veto light curve. CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, URSC, IUCAA, SAC, and PRL. The Indian Space Research Organisation funded, managed, and facilitated the project. CZTI GRB detections are reported regularly on the payload site at: http://astrosat.iucaa.in/czti/?q=grb
GCN 41283 table
GRB_name GRB250807A
GCN_number 41283
Detection_method Konus-Wind Det
ra 51.4200°
decl -47.8770°
Circular_text TITLE: GCN CIRCULAR NUMBER: 41283 SUBJECT: GRB 250807A: SVOM/GRM observation DATE: 25/08/08 11:07:22 GMT FROM: Chenwei Wang at IHEP SVOM/GRM team: Chen-Wei Wang, Shi-Jie Zheng, Yue Huang, Shao-Lin Xiong, Shuang-Nan Zhang (IHEP) SVOM/ECLAIRs team: Sebastien Guillot (IRAP) Report on behalf of the SVOM team: SVOM/GRM was triggered in-flight by GRB 250807A (SVOM trigger reference: sb25080702) at 2025-08-07T10:46:06.700 UTC (T0), which is also detected by Swift/BAT (N. J. Klingler et al., GCN #41262), AstroSat (S.Salunke et al., GCN #41281) and Konus-Wind. With the event-by-event data downloaded through the X-band ground station, the GRM light curve shows that this burst consists of multiple pulses with a T90 of 71.0 +4.5/-7.0 s in the 15-5000 keV band. The SVOM/GRM light curve can be found here: https://www.bursthub.cn//admin/static/svgrb250807A.png In addition, the position of this burst, as determined by Swift/BAT (RA= 51.420, DEC= -47.877, GCN #41064), is located at about 69 degrees from the SVOM optical axis, which is outside the ECLAIRs field of view. Nonetheless, the burst is seen (via analysis of X-band data) in the ECLAIRs data above 50 keV at the T0 given by GRM, likely through the ECLAIRs shielding. With this localization, the time-averaged spectrum from T0-15 to T0+130 s is best fitted by a power law function with an exponential high-energy cutoff. The power law index is -1.19 +/-0.03 and the cutoff energy, parameterized as Epeak, is 547 +52/-45 keV. The event fluence (10-1000 keV) in this time interval is (1.00 +/-0.10)E-04 erg/cm^2. Thus GRB 250807A is consistent with Type II GRBs in the 'Amati' relation diagram, as shown at: https://www.bursthub.cn//admin/static/grb250807A_amati.png The Space Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA, China), National Center for Space Studies (CNES, France) and the Chinese Academy of Sciences (CAS, China), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. GRM is developed by the Institute of High Energy Physics (IHEP) of CAS. The SVOM point of contact for this burst is: Chen-Wei Wang (IHEP)(cwwang@ihep.ac.cn)
GCN 41290 table
GRB_name GRB250807A
GCN_number 41290
Detection_method Swift-XRT Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 41290 SUBJECT: GRB 250807A: Swift-XRT refined Analysis DATE: 25/08/08 15:31:42 GMT FROM: Phil Evans at U of Leicester J.P. Osborne (U. Leicester), R. Brivio (INAF-OAB), A. D'Ai (INAF-IASFPA), S. Campana (INAF-OAB), D.N. Burrows (PSU), M.A. Williams (PSU), S. Dichiara (PSU), K.L. Page (U. Leicester) and P.A. Evans report on behalf of the Swift-XRT team: We have analysed 4.6 ks of XRT data for GRB 250807A, from 93 s to 91.2 ks after the trigger. The data comprise 1.2 ks in Windowed Timing (WT) mode (the first 5 s were taken while Swift was slewing) with the remainder in Photon Counting (PC) mode. The late-time light curve (from T0+6.7 ks) can be modelled with a power-law decay with a decay index of alpha=1.75 (+0.11, -0.10). A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 1.96 (+/-0.03). The best-fitting absorption column is 1.90 (+/-0.11) x 10^21 cm^-2, in excess of the Galactic value of 1.4 x 10^20 cm^-2 (Willingale et al. 2013). The PC mode spectrum has a photon index of 1.85 (+0.11, -0.10) and a best-fitting absorption column of 1.8 (+0.4, -0.3) x 10^21 cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.9 x 10^-11 (4.9 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 1.8 (+0.4, -0.3) x 10^21 cm^-2 Galactic foreground: 1.4 x 10^20 cm^-2 Excess significance: 8.0 sigma Photon index: 1.85 (+0.11, -0.10) The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/01340514. This circular is an official product of the Swift-XRT team.
GCN 41291 table
GRB_name GRB250807A
GCN_number 41291
Detection_method Swift-UVOT Det
Circular_text TITLE: GCN CIRCULAR NUMBER: 41291 SUBJECT: GRB 250807A: Swift/UVOT Detection DATE: 25/08/08 16:24:35 GMT FROM: s.shilling@lancaster.ac.uk S. P. R. Shilling (Lancaster U.) and N. J. Klingler (GSFC/UMBC/CRESSTII) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 250807A 111 s after the BAT trigger (Klingler et al., GCN Circ. 41262). A source consistent with the enhanced XRT position (Evans et al., GCN Circ. 41270) is detected in the initial UVOT exposures. Preliminary detections and 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag white 111 261 147 18.00 +/- 0.04 v 653 1769 136 >18.8 b 579 1695 117 >19.5 u 323 1840 361 19.88 +/- 0.31 w1 702 1818 117 >19.0 w2 801 821 19 >17.7 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.011 in the direction of the burst (Schlegel et al. 1998).
GCN 41295 table
GRB_name GRB250807A
GCN_number 41295
Detection_method Konus-Wind Det
t_trigger 10:46:06.990 UTC
Circular_text TITLE: GCN CIRCULAR NUMBER: 41295 SUBJECT: Konus-Wind detection of GRB 250807A DATE: 25/08/08 18:25:17 GMT FROM: Dmitry Svinkin at Ioffe Institute D. Svinkin, D. Frederiks, A. Lysenko, A. Ridnaia, A. Tsvetkova, M. Ulanov, and T. Cline on behalf of the Konus-Wind team, report: The long-duration GRB 250807A (Swift-BAT detection: Klingler et al., GCN 41262; AstroSat-CZTI detection: Salunke et al., GCN 41281; SVOM-GRM detection: Wang et al., GCN 41283) triggered Konus-Wind at T0=38766.990 s UT (10:46:06.990). The burst light curve shows a multipeaked structure which starts at ~T0-2.3 s and has a total duration of ~79 s. The emission is seen up to ~2 MeV. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB250807_T38766/ As observed by Konus-Wind, the burst had the total fluence of 1.03(-0.09,+0.08)x10^-4 erg/cm2, and the 64-ms peak flux, measured from T0+35.904 s, of 1.11(-0.10,+0.10)x10^-5 erg/cm2/s (both in the 20 keV - 10 MeV energy range). The time-averaged spectrum of the burst (measured from T0 to T0+79.104 s) is best fit in the 20 keV - 10 MeV range by the GRB (Band) model with the following parameters: the low-energy photon index alpha = -1.04(-0.04,+0.04), the high energy photon index beta = -2.74(-0.66,+0.26), the peak energy Ep = 369(-26,+26) keV (chi2 = 132/97 dof). The spectrum near the maximum count rate (measured from T0+29.952 to T0+38.144 s) is best fit in the 20 keV - 10 MeV range by a power law with exponential cutoff model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) with alpha = -1.04(-0.05,+0.05) and Ep = 390(-25,+28) keV (chi2 = 105/86 dof). Fitting by a GRB (Band) model yields the same alpha and Ep, and an upper limit on the high energy photon index: beta < -3.5 (chi2 = 105/85 dof). All the quoted errors are at the 68% confidence level. All the quoted values are preliminary.
GCN 41299 table
GRB_name GRB250807A
GCN_number 41299
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 41299 SUBJECT: GRB 250807A: SVOM/VT optical continued observation DATE: 25/08/09 09:00:02 GMT FROM: Yinuo Ma Y. N. Ma, Z. H. Yao, L. P. Xin, Y. L. Qiu, C. Wu, H. L. Li, X. H. Han, Y. Xu, J. Wang, P. P. Zhang, W. J. Xie, Y. J. Xiao, H. B. Cai, L. Lan, J. S. Deng, J. Y. Wei (NAOC), J. Palmerio (CEA) report on behalf of the SVOM/VT team. SVOM/VT conducted continued observations of GRB 250807A detected by Swift/BAT（Klingler et al., GCN 41262), AstroSat-CZTI (Salunke et al., GCN 41281), SVOM/GRM (Wang et al,. GCN 41283) and Konus-Wind (Svinkin et al,. GCN 41295). The magnitude of the optical afterglow (Klingler et al., GCN 41262; Ma et al., GCN 41274; Shilling et al., GCN 41291) is: mid time | exposure time (s) | band | mag (AB) | mag err -----------|-------------------|------|----------|-------- 18.25h | 31*70 | VT_R | 21.59 | 0.08 Our photometry was not corrected for Galactic extinction. The Space Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA, China), National Centre for Space Studies (CNES, France) and the Chinese Academy of Sciences (CAS, China), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. VT was jointly developed by Xi'an Institute of Optics and Precision Mechanics (XIOPM), CAS and National astronomical observatories (NAOC), CAS.