GRB250331B

This page lists all entries on GRB250331B in GRBweb

Summary Swift GCN 39958 GCN 39962 GCN 39974 GCN 39980 GCN 39995 GCN 39996 GCN 40002 GCN 40056

Summary table
Variable Value Source
T0 4:19:43 UTC GCN_circulars,Swift Det
ra 71.3722° Swift
decl 43.8126° Swift
pos_error 4.66e-04° Swift
GBM_located False
mjd 60765.18035879629 GCN_circulars,Swift Det
Swift table
GRB_name GRB250331B
t_trigger 4:19:43 UTC
ra 71.3722°
decl 43.8126°
pos_error 4.66e-04°
GCN 39958 table
GRB_name GRB250331B
GCN_number 39958
Detection_method Swift Det
t_trigger 4:19:43 UTC
ra 71.3810°
decl 43.8050°
Circular_text TITLE: GCN CIRCULAR NUMBER: 39958 SUBJECT: GRB 250331B: Swift detection of a burst DATE: 25/03/31 04:47:31 GMT FROM: David Palmer at LANL S. B. Cenko (GSFC), C. Gronwall (PSU), R. Gupta (NASA GSFC), K. L. Page (U Leicester), D. M. Palmer (LANL) and M. H. Siegel (PSU) report on behalf of the Neil Gehrels Swift Observatory Team: At 04:19:43 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 250331B (trigger=1299965). Swift slewed to the burst after a brief delay to clear an observing constraint. The BAT on-board calculated location is RA, Dec 71.381, +43.805 which is RA(J2000) = 04h 45m 31s Dec(J2000) = +43d 48' 17" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a single-peak structure with a duration of about 8 sec. The peak count rate was ~1400 counts/sec (15-350 keV), at ~2 sec after the trigger. The XRT began observing the field at 04:24:57.3 UT, 313.9 seconds after the BAT trigger. Using promptly downlinked data we find an uncatalogued X-ray source with an enhanced position: RA, Dec 71.37364, 43.81080 which is equivalent to: RA(J2000) = 04h 45m 29.67s Dec(J2000) = +43d 48' 38.9" with an uncertainty of 1.9 arcseconds (radius, 90% containment). This location is 28 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 https://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 does not constrain the column density. UVOT took a finding chart exposure of 150 seconds with the White filter starting 317 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 100% of the XRT error circle. The typical 3-sigma upper limit has been about 19.6 mag. 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 large, but uncertain, extinction expected. Burst Advocate for this burst is S. B. Cenko (brad.cenko AT nasa.gov). 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 39962 table
GRB_name GRB250331B
GCN_number 39962
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 39962 SUBJECT: GRB 250331B: COLIBRÍ/DDRAGO optical upper limit DATE: 25/03/31 06:21:34 GMT FROM: damien dornic Damien Dornic (CPPM), Margarita Pereyra (UNAM), Jean-Grégoire Ducoin (CPPM), Jean-Luc Atteia (IRAP), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Dalya Akl (AUS), Camila Angulo (UNAM), Sarah Antier (OCA), Rosa L. Becerra (U Roma), Nathaniel R. Butler (ASU), Francis Fortin (IRAP), Ny Avo Rakotondrainibe (LAM), Noémie Globus (UNAM), Kin Ocelotl López (UNAM), Diego López-Cámara (UNAM), Francesco Magnani (CPPM), Enrique Moreno Méndez (UNAM), Benjamin Schneider (LAM) and Antonio de Ugarte Postigo (LAM) report: We imaged the field of Swift/BAT GRB 250331B (Cenko et al., GCN Circ. 39958) with the DDRAGO wide-field imager on the COLIBRÍ telescope at the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir in Mexico. We started observing at 2025-03-31 04:21:10 UTC (87 s after the trigger) and obtained a total of 100 s exposure in the i filter. The data were coadded with the COLIBRÍ pipeline and analyzed in STDWeb/STDPipe (Karpov 2025), with photometric calibration against Pan-STARRS DR1 and image subtraction against Pan-STARRS DR2. Our photometry is in the AB system and is not corrected for Galactic extinction. At the XRT localization, we do not find any optical counterpart to a 3-sigma limiting magnitude of: i > 20.96 We warmly thank the COLIBRÍ and DDRAGO engineering teams and the staff of the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir.
GCN 39974 table
GRB_name GRB250331B
GCN_number 39974
Detection_method Swift-XRT Det
ra 71.3722°
decl 43.8126°
Circular_text TITLE: GCN CIRCULAR NUMBER: 39974 SUBJECT: GRB 250331B: Enhanced Swift-XRT position DATE: 25/03/31 15:22:51 GMT FROM: Phil Evans at U of Leicester J.P. Osborne, A.P. Beardmore, P.A. Evans and M.R. Goad (U. Leicester) report on behalf of the Swift-XRT team. Using 824 s of XRT Photon Counting mode data and 1 UVOT images for GRB 250331B, 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 = 71.37215, +43.81257 which is equivalent to: RA (J2000): 04h 45m 29.32s Dec (J2000): +43d 48' 45.2" with an uncertainty of 3.6 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 39980 table
GRB_name GRB250331B
GCN_number 39980
Detection_method Swift Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 39980 SUBJECT: Swift GRB 250331B: Global MASTER-Net observations report DATE: 25/03/31 17:47:41 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs V.Lipunov, E.Gorbovskoy, N.Tiurina, P.Balanutsa, , D.Vlasenko, I.Panchenko, A.Kuznetsov, G.Antipov, A.Sankovich, A.Sosnovskij, Yu.Tselik, M.Gulyaev, Ya.Kechin, V.Senik, A.Chasovnikov, K.Labsina, I. Gorbunov (Lomonosov MSU), O.Gress, N.Budnev (ISU), C.Francile, F. Podesta, R.Podesta, E. Gonzalez (Observatorio Astronomico Felix Aguilar (OAFA), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity) D.Buckley (SAAO), R.Rebolo (The Instituto de Astrofisica de Canarias), L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory) MASTER-SAAO robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in South Africa (South African Astronomical Observatory) was pointed to the Swift GRB 250331B ( S. B. Cenko et al., GCN 39958) errorbox 47556 sec after notice time and 47612 sec after trigger time at 2025-03-31 17:33:15 UT, with upper limit up to 16.9 mag. Observations started at twilight. The observations began at zenith distance = 85 deg. The sun altitude is -13.0 deg. The galactic latitude b = -1 deg., longitude l = 161 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2828939 We obtain a following upper limits. Tmid-T0 | Site |Filt.| Expt. | Limit| Comment _________|_____________________|_____|_______|______|________ 47702 | MASTER-SAAO | C | 180 | 16.5 | 47902 | MASTER-SAAO | C | 180 | 16.7 | 48101 | MASTER-SAAO | C | 180 | 16.9 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited.
GCN 39995 table
GRB_name GRB250331B
GCN_number 39995
Detection_method Swift-XRT Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 39995 SUBJECT: GRB 250331B: Swift-XRT refined Analysis DATE: 25/04/01 07:45:10 GMT FROM: Phil Evans at U of Leicester T. Sbarrato (INAF-OAB), P. D'Avanzo (INAF-OAB), J.A. Kennea (PSU), D.N. Burrows (PSU), M. A. Williams (PSU), A.P. Beardmore (U. Leicester), J.P. Osborne (U. Leicester), M.G. Bernardini (INAF-OAB) and P.A. Evans report on behalf of the Swift-XRT team: We have analysed 5.5 ks of XRT data for GRB 250331B, from 321 s to 35.1 ks after the BAT trigger. The data are entirely in Photon Counting (PC) mode. The light curve can be modelled with a power-law decay with a decay index of alpha=1.11 (+0.17, -0.14). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 2.2 (+0.9, -0.8). The best-fitting absorption column is 2.1 (+1.5, -1.1) x 10^22 cm^-2, in excess of the Galactic value of 6.6 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 5.7 x 10^-11 (1.6 x 10^-10) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 2.1 (+1.5, -1.1) x 10^22 cm^-2 Galactic foreground: 6.6 x 10^21 cm^-2 Excess significance: 2.2 sigma Photon index: 2.2 (+0.9, -0.8) If the light curve continues to decay with a power-law decay index of 1.11, the count rate at T+24 hours will be 7.9 x 10^-4 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 4.5 x 10^-14 (1.2 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/01299965. This circular is an official product of the Swift-XRT team.
GCN 39996 table
GRB_name GRB250331B
GCN_number 39996
Detection_method Swift-XRT Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 39996 SUBJECT: GRB 250331B: Swift-XRT refined Analysis DATE: 25/04/01 07:45:13 GMT FROM: Phil Evans at U of Leicester P. D'Avanzo (INAF-OAB), D.N. Burrows (PSU), M. A. Williams (PSU), S. Dichiara (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), M.G. Bernardini (INAF-OAB), E. Ambrosi (INAF-IASFPA) and P.A. Evans report on behalf of the Swift-XRT team: We have analysed 5.5 ks of XRT data for GRB 250331B, from 321 s to 35.1 ks after the BAT trigger. The data are entirely in Photon Counting (PC) mode. The light curve can be modelled with a power-law decay with a decay index of alpha=1.11 (+0.17, -0.14). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 2.2 (+0.9, -0.8). The best-fitting absorption column is 2.1 (+1.5, -1.1) x 10^22 cm^-2, in excess of the Galactic value of 6.6 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 5.7 x 10^-11 (1.6 x 10^-10) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 2.1 (+1.5, -1.1) x 10^22 cm^-2 Galactic foreground: 6.6 x 10^21 cm^-2 Excess significance: 2.2 sigma Photon index: 2.2 (+0.9, -0.8) If the light curve continues to decay with a power-law decay index of 1.11, the count rate at T+24 hours will be 7.9 x 10^-4 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 4.5 x 10^-14 (1.2 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/01299965. This circular is an official product of the Swift-XRT team.
GCN 40002 table
GRB_name GRB250331B
GCN_number 40002
Detection_method Swift-UVOT Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 40002 SUBJECT: GRB 250331B: Swift/UVOT Upper Limits DATE: 25/04/01 13:04:29 GMT FROM: Mike Siegel at PSU/Swift MOC M. H. Siegel (PSU) and S. B. Cenko (GSFC) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 250331B 317 s after the BAT trigger (Cenko et al., GCN Circ. 39958). No optical afterglow consistent with the XRT position (Osborne et al., GCN Circ. 39974) 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 317 467 147 >19.5 white 317 1020 334 >19.9 v 474 1070 78 >18.3 b 572 764 39 >18.3 u 547 1144 58 >18.6 w1 523 1120 58 >18.0 m2 670 690 19 >17.7 w2 621 1046 58 >18.4 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.979 in the direction of the burst (Schlegel et al. 1998).
GCN 40056 table
GRB_name GRB250331B
GCN_number 40056
Detection_method Swift-BAT Det
ra 71.3770°
decl 43.7940°
Circular_text TITLE: GCN CIRCULAR NUMBER: 40056 SUBJECT: GRB 250331B Swift-BAT refined analysis DATE: 25/04/04 16:16:25 GMT FROM: Mike Moss at NASA GSFC S. Laha (GSFC/UMBC), S. D. Barthelmy (GSFC), S. B. Cenko (GSFC), R. Gupta (GSFC), H. A. Krimm (NSF), A. Y. Lien (U Tampa), C. B. Markwardt (GSFC), M. J. Moss (GSFC), D. M. Palmer (LANL), T. Parsotan (GSFC), D. Sadaula (GSFC/UMBC), T. Sakamoto (AGU) (i.e. the Swift-BAT team): Using the data set from T-240 to T+842 sec from the recent telemetry downlink, we report further analysis of BAT GRB 250331B (trigger #1299965) (Cenko, et al., GCN Circ. 39958). The BAT ground-calculated position is RA, Dec = 71.377, 43.794 deg which is RA(J2000) = 04h 45m 30.4s Dec(J2000) = +43d 47' 39.1" with an uncertainty of 2.6 arcmin, (radius, sys+stat, 90% containment). The partial coding was 55%. The mask-weighted light curve displays a single dim pulse. The T90 (15-350 keV) is 3.95 +- 0.77 sec (estimated error including systematics). The time-averaged spectrum from T-0.72 to T+3.76 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 2.61 +- 0.38. The fluence in the 15-150 keV band is 1.5 +- 0.3 x 10^-07 erg/cm2. The 1-sec peak photon flux measured from T+1.28 sec in the 15-150 keV band is 0.9 +- 0.2 ph/cm2/sec. All the quoted errors are at the 90% confidence level. The results of the batgrbproduct analysis are available at https://swift.gsfc.nasa.gov/results/batgrbcat/BAT_refined_circular/1299965