GRB250331C

This page lists all entries on GRB250331C in GRBweb

Summary Swift GCN 39959 GCN 39960 GCN 39963 GCN 39977 GCN 39981 GCN 39997 GCN 40003 GCN 40013 GCN 40057

Summary table
Variable Value Source
T0 4:37:40 UTC GCN_circulars,Swift Det
ra 80.9562° Swift
decl 33.0635° Swift
pos_error 2.85e-04° Swift
GBM_located False
mjd 60765.192824074074 GCN_circulars,Swift Det
Swift table
GRB_name GRB250331C
t_trigger 4:37:40 UTC
ra 80.9562°
decl 33.0635°
pos_error 2.85e-04°
GCN 39959 table
GRB_name GRB250331C
GCN_number 39959
Detection_method Swift Det
t_trigger 4:37:40 UTC
ra 80.9930°
decl 33.0290°
Circular_text TITLE: GCN CIRCULAR NUMBER: 39959 SUBJECT: GRB 250331C: Swift detection of a burst DATE: 25/03/31 04:55:40 GMT FROM: David Palmer at LANL S. B. Cenko (GSFC), C. Gronwall (PSU), 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 04:37:40 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 250331C (trigger=1299967). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 80.993, +33.029 which is RA(J2000) = 05h 23m 58s Dec(J2000) = +33d 01' 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 25 sec. The peak count rate was ~800 counts/sec (15-350 keV), at ~1 sec after the trigger. The XRT began observing the field at 04:39:51.5 UT, 130.9 seconds after the BAT trigger. Using promptly downlinked data we find a bright, uncatalogued X-ray source located at RA, Dec 80.95740, 33.06310 which is equivalent to: RA(J2000) = 05h 23m 49.78s Dec(J2000) = +33d 03' 47.2" with an uncertainty of 3.7 arcseconds (radius, 90% containment). This location is 163 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. A power-law fit to a spectrum formed from promptly downlinked event data gives a column density consistent with the Galactic value of 6.49 x 10^21 cm^-2 (Willingale et al. 2013). The initial flux in the 2.5 s image was 1.04e-09 erg cm^-2 s^-1 (0.2-10 keV). UVOT took a finding chart exposure of 150 seconds with the White filter starting 139 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 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 39960 table
GRB_name GRB250331C
GCN_number 39960
Detection_method Swift-XRT Other
ra 80.9564°
decl 33.0632°
Circular_text TITLE: GCN CIRCULAR NUMBER: 39960 SUBJECT: GRB 250331C: Prompt enhanced Swift-XRT position DATE: 25/03/31 05:45:04 GMT FROM: Phil Evans at U of Leicester P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team: Using 1.6 ks of promptly downlinked XRT event data for GRB 250331C, we find an enhanced XRT position of the afterglow: RA, Dec: 80.95640, 33.06317 which is equivalent to: RA (J2000) = 05 23 49.54 Dec (J2000) = +33 03 47.4 with an uncertainty of 1.9 arcseconds (radius, 90% confidence). Analysis of the promptly available data is online at http://www.swift.ac.uk/sper/1299967. Position enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans et al. (2009, MNRAS, 397, 1177). This circular is an official product of the Swift-XRT team.
GCN 39963 table
GRB_name GRB250331C
GCN_number 39963
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 39963 SUBJECT: GRB 250331C: COLIBRÍ/DDRAGO optical upper limit DATE: 25/03/31 06:24:32 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 250331C (Cenko et al., GCN Circ. 39959) 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 04:43:50 UTC (370 s after the trigger) and obtained a total of 720 s of exposure time 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 (Evans et al. 39960), we do not find any optical counterpart to a 3-sigma limiting magnitude of: i > 22.26 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 39977 table
GRB_name GRB250331C
GCN_number 39977
Detection_method Swift-XRT Det
ra 80.9562°
decl 33.0635°
Circular_text TITLE: GCN CIRCULAR NUMBER: 39977 SUBJECT: GRB 250331C: Enhanced Swift-XRT position DATE: 25/03/31 16:38:10 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 1624 s of XRT Photon Counting mode data and 2 UVOT images for GRB 250331C, 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 = 80.95619, +33.06347 which is equivalent to: RA (J2000): 05h 23m 49.49s Dec (J2000): +33d 03' 48.5" with an uncertainty of 2.2 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 39981 table
GRB_name GRB250331C
GCN_number 39981
Detection_method Swift Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 39981 SUBJECT: Swift GRB 250331C: Global MASTER-Net observations report DATE: 25/03/31 18:16:57 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 250331C ( S. B. Cenko et al., GCN 39959) errorbox 48174 sec after notice time and 48531 sec after trigger time at 2025-03-31 18:06:32 UT, with upper limit up to 18.0 mag. The observations began at zenith distance = 75 deg. The sun altitude is -20.0 deg. The galactic latitude b = -1 deg., longitude l = 174 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2828956 We obtain a following upper limits. Tmid-T0 | Site |Filt.| Expt. | Limit| Comment _________|_____________________|_____|_______|______|________ 48622 | MASTER-SAAO | C | 180 | 17.9 | 48821 | MASTER-SAAO | C | 180 | 18.0 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited.
GCN 39997 table
GRB_name GRB250331C
GCN_number 39997
Detection_method Swift-XRT Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 39997 SUBJECT: GRB 250331C: Swift-XRT refined Analysis DATE: 25/04/01 07:45:44 GMT FROM: Phil Evans at U of Leicester M. A. Williams (PSU), S. Dichiara (PSU), J.A. Kennea (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), M.G. Bernardini (INAF-OAB), E. Ambrosi (INAF-IASFPA) , M. Capalbi (INAF-IASFPA) and P.A. Evans report on behalf of the Swift-XRT team: We have analysed 3.9 ks of XRT data for GRB 250331C, from 137 s to 62.7 ks after the BAT trigger. The data comprise 95 s in Windowed Timing (WT) mode with the remainder in Photon Counting (PC) mode. The light curve can be modelled with a power-law decay with a decay index of alpha=2.81 (+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 2.11 (+0.11, -0.08). The best-fitting absorption column is consistent with the Galactic value of 6.5 x 10^21 cm^-2 (Willingale et al. 2013). The PC mode spectrum has a photon index of 1.65 (+0.32, -0.30) and a best-fitting absorption column of 9.0 (+3.4, -2.5) x 10^21 cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 5.9 x 10^-11 (8.6 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 9.0 (+3.4, -2.5) x 10^21 cm^-2 Galactic foreground: 6.5 x 10^21 cm^-2 Excess significance: <1.6 sigma Photon index: 1.65 (+0.32, -0.30) If the light curve continues to decay with a power-law decay index of 2.81, the count rate at T+24 hours will be 3.2 x 10^-7 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.9 x 10^-17 (2.8 x 10^-17) erg cm^-2 s^-1. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/01299967. This circular is an official product of the Swift-XRT team.
GCN 40003 table
GRB_name GRB250331C
GCN_number 40003
Detection_method Swift-UVOT Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 40003 SUBJECT: GRB 250331C: Swift/UVOT Upper Limits DATE: 25/04/01 13:06:09 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 250331C 140 s after the BAT trigger (Cenko et al., GCN Circ. 39959). No optical afterglow consistent with the XRT position (Beardmore et al., GCN Circ. 39977) 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 140 289 147 >21.1 u_FC 297 547 246 >19.9 white 140 1717 411 >22.3 v 628 1767 136 >19.1 b 553 1863 133 >20.1 u 297 1841 363 >20.1 w1 676 1817 136 >19.1 m2 652 1792 136 >19.8 w2 603 1743 136 >20.0 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.921 in the direction of the burst (Schlegel et al. 1998).
GCN 40013 table
GRB_name GRB250331C
GCN_number 40013
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 40013 SUBJECT: GRB 250331C: Calapai Observatory, Massa S. Giorgio (Messina), upper limit DATE: 25/04/02 20:48:13 GMT FROM: Giovanni Calapai at Calapai Astronomical Observatory, Massa S. Giorgio, Messina, Italy Giovanni Calapai at Calapai Astronomical Observatory, Massa S. Giorgio, (Messina) Italy Member of: GRB/UAI Gamma Ray Burst Section of Unione Astrofili Italiani. Report: We imaged the field of GRB 250331C detected by Swift Burst Alert Telescope (BAT) (Cenko et al. GCN 39959), with the 11 inches Schmidt-Cassegrain (Celestron 11) telescope F/D=6,3. The observations were started at 2025-03-31 20:59 UT (approximately 16.37 hours after burst) stacking a set of unfiltered CCD image. The observations were made with modest sky conditions and the target low on the horizon. We co-added 30 exposures of 60 sec each. Start T0+ End T0+ CR lim 16.37 hour 16.92 hour 18.7 We did not found any optical counterpart in the error box of the XRTcandidate. Evans GCN 39960 Magnitudes were estimated with the PanSTARRS cat. and are not corrected for galactic dust extinction. Our observations are consistent with other already reported Dornic et al. (GCN 39963), Lipunov et al. (GCN 39981), Siegel et al. (GCN 40003). The message may be cited.
GCN 40057 table
GRB_name GRB250331C
GCN_number 40057
Detection_method Swift-BAT Det
ra 80.9630°
decl 33.0680°
Circular_text TITLE: GCN CIRCULAR NUMBER: 40057 SUBJECT: GRB 250331C Swift-BAT refined analysis DATE: 25/04/04 16:17:44 GMT FROM: Mike Moss at NASA GSFC A. Y. Lien (U Tampa), S. D. Barthelmy (GSFC), S. B. Cenko (GSFC), R. Gupta (GSFC), H. A. Krimm (NSF), S. Laha (GSFC/UMBC), 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-239 to T+963 sec from the recent telemetry downlink, we report further analysis of BAT GRB 250331C (trigger #1299967) (Cenko, et al., GCN Circ. 39959). The BAT ground-calculated position is RA, Dec = 80.963, 33.068 deg which is RA(J2000) = 05h 23m 51.0s Dec(J2000) = +33d 04' 03.4" with an uncertainty of 2.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 100%. The mask-weighted light curve shows a dim pulse of emission with some possible complex structure. The T90 (15-350 keV) is 70.10 +- 11.70 sec (estimated error including systematics). The time-averaged spectrum from T-12.59 to T+66.67 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.88 +- 0.23. The fluence in the 15-150 keV band is 6.6 +- 1.0 x 10^-07 erg/cm2. The 1-sec peak photon flux measured from T-3.19 sec in the 15-150 keV band is 0.3 +- 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/1299967