GRB250306A

This page lists all entries on GRB250306A in GRBweb

Summary IPN Swift GCN 39606 GCN 39608 GCN 39611 GCN 39616 GCN 39617 GCN 39619

Summary table
Variable Value Source
T0 16:30:04.612 UTC GCN_circulars,Konus-Wind Det
ra 354.7300° Swift
decl -47.9930° Swift
pos_error 2.33e-02° Swift
GBM_located False
mjd 60740.68755337963 GCN_circulars,Konus-Wind Det
IPN table
GRB_name GRB250306A
ra 354.7292°
decl -48.0000°
pos_error 5.00e-02°
Swift table
GRB_name GRB250306A
t_trigger 16:30:08 UTC
ra 354.7300°
decl -47.9930°
pos_error 2.33e-02°
GCN 39606 table
GRB_name GRB250306A
GCN_number 39606
Detection_method Swift Det
t_trigger 16:30:08 UTC
ra 354.7300°
decl -47.9930°
Circular_text TITLE: GCN CIRCULAR NUMBER: 39606 SUBJECT: GRB 250306A: Swift detection of a burst DATE: 25/03/06 16:51:42 GMT FROM: David Palmer at LANL P. A. Evans (U Leicester), R. Gupta (NASA GSFC), J. A. Kennea (PSU), K. L. Page (U Leicester) and D. M. Palmer (LANL) report on behalf of the Neil Gehrels Swift Observatory Team: At 16:30:08 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 250306A (trigger=1293340). Swift did not slew to the burst. The BAT on-board calculated location is RA, Dec 354.730, -47.993 which is RA(J2000) = 23h 38m 55s Dec(J2000) = -47d 59' 35" 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 10 sec. The peak count rate was ~14,000 counts/sec (15-350 keV), at ~0 sec after the trigger. Due to a Sun observing constraint, Swift cannot slew to the BAT position until 01:23 UT on 2025 March 18. There will thus be no XRT or UVOT data for this trigger before this time. Burst Advocate for this burst is P. A. Evans (pae9 AT leicester.ac.uk). 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 39608 table
GRB_name GRB250306A
GCN_number 39608
Detection_method Swift Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 39608 SUBJECT: Swift GRB 250306A: Global MASTER-Net observations report DATE: 25/03/06 18:13:38 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 250306A ( P. A. Evans et al., GCN 39606) errorbox 4918 sec after notice time and 5733 sec after trigger time at 2025-03-06 18:05:42 UT, with upper limit up to 18.3 mag. Observations started at twilight. The observations began at zenith distance = 74 deg. The sun altitude is -12.9 deg. The galactic latitude b = -65 deg., longitude l = 332 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2802578 We obtain a following upper limits. Tmid-T0 | Site |Filt.| Expt. | Limit| Comment _________|_____________________|_____|_______|______|________ 5823 | MASTER-SAAO | C | 180 | 18.3 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited.
GCN 39611 table
GRB_name GRB250306A
GCN_number 39611
Detection_method AstroSat CZTI
Circular_text TITLE: GCN CIRCULAR NUMBER: 39611 SUBJECT: GRB 250306A: AstroSat CZTI detection DATE: 25/03/07 05:36:41 GMT FROM: Gaurav Waratkar at IIT Bombay M. Tembhurnikar (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 long duration GRB 250306A which was also detected by Swift/BAT (P. A. Evans et al., GCN Circ. 39606). The source was clearly detected in the CZT detectors in the 20-200 keV energy range. The light curve peaks at 2025-03-06 16:30:09.5 UTC. The measured peak count rate associated with the burst is 298 (+41, -38) counts/s above the background in the combined data of three quadrants (out of four), with a total of 717 (+168, -110) counts. The local mean background count rate was 220 (+3, -6) counts/s. Using cumulative rates, we measure a T90 of 7.2 (+1.5, -1.5) s. The source was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve peaks at 2025-03-06 16:30:09.0 UTC. The measured peak count rate associated with the burst is 1146 (+81, -74) counts/s above the background in the combined data of all quadrants, with a total of 3170 (+271, -287) counts. The local mean background count rate was 1370 (+7, -8) counts/s. We measure a T90 of 6.8 (+0.7, -1.1) 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 39616 table
GRB_name GRB250306A
GCN_number 39616
Detection_method Swift-BAT Det
ra 354.7300°
decl -47.9930°
Circular_text TITLE: GCN CIRCULAR NUMBER: 39616 SUBJECT: GRB 250306A: NuSTAR detection of the prompt emission DATE: 25/03/07 17:27:29 GMT FROM: Brian Grefenstette at Caltech/NuSTAR B. Grefenstette (Caltech) reports on behalf of the NuSTAR Search for INteresting Gamma-ray Signals (SINGS) working group: The NuSTAR SINGS working group reports the detection of prompt emission from the Long GRB 250306A in both the NuSTAR CsI anti-coincidence shields. This GRB was identified through a blind search using the CsI shield rates. Details of the search algorithm will be described in a future paper. The NuSTAR SINGS algorithm triggered at 2025-03-06 16:30:03 (with a resolution ~5-seconds). This is consistent with the detections by the Neil Gehrels Swift BAT (Evans et al, GCN circ. 39606) and ASTROSAT (Tembhurnikar et al., GCN circ. 39611). The NuSTAR CsI shield data are recorded at 1 Hz. The GRB appears to be composed of a single, narrow burst with a duration of a few seconds with a peak rate of ~4,000 counts per second. The baseline rate is ~1,000 cps during this time period. We also see a single short burst above 100 keV in the CdZnTe detectors. Using the localization from Swift/BAT at RA = 354.730, Dec = -47.993 implies an offset from the NuSTAR boresight of 64.95 deg (e.g., through the side of the instrument) and the offset from the geocenter of 114-deg Discovery report and preliminary analysis for this GRB can be found here: https://nustarsoc.caltech.edu/NuSTAR_Public/grbs/reports/2025/250306A/ Information on NuSTAR SINGS can be found here: https://nustarsoc.caltech.edu/NuSTAR_Public/grbs/ NuSTAR is a NASA Small Explorer mission led by Caltech and managed by JPL for NASA’s Science Mission Directorate in Washington.
GCN 39617 table
GRB_name GRB250306A
GCN_number 39617
Detection_method Swift-BAT Det
ra 354.7240°
decl -47.9980°
Circular_text TITLE: GCN CIRCULAR NUMBER: 39617 SUBJECT: GRB 250306A: Swift-BAT refined analysis DATE: 25/03/07 18:38:30 GMT FROM: Rahul Gupta at NASA GSFC T. Parsotan (GSFC), S. D. Barthelmy (GSFC), P. A. Evans (U Leicester), R. Gupta (GSFC), H. A. Krimm (NSF), S. Laha (GSFC/UMBC), A. Y. Lien (U Tampa), C. B. Markwardt (GSFC), M. J. Moss (GSFC), D. M. Palmer (LANL), D. Sadaula (GSFC/UMBC), T. Sakamoto (AGU) (i.e. the Swift-BAT team): Using the data set from T-240 to T+961 sec from the recent telemetry downlink, we report further analysis of BAT GRB 250306A (trigger #1293340) (Evans et al., GCN Circ. 39606). The BAT ground-calculated position is RA, Dec = 354.724, -47.998 deg which is RA(J2000) = 23h 38m 53.7s Dec(J2000) = -47d 59' 52.8" with an uncertainty of 1.1 arcmin, (radius, sys+stat, 90% containment). The partial coding was 13%. The mask-weighted BAT light curve shows a distinct peak at around BAT trigger time, followed by a rapid decay and a quieter post-peak phase. T90 (15-350 keV) is 11.44 +- 2.44 sec (estimated error including systematics). The time-averaged spectrum from T-1.52 to T+19.04 sec is best fit by a power law with an exponential cutoff. This fit gives a photon index 0.87 +- 0.24, and Epeak of 132.8 +- 45.6 keV (chi squared 62.11 for 56 d.o.f.). For this model the total fluence in the 15-150 keV band is 8.9 +- 0.3 x 10^-06 erg/cm2 and the 1-sec peak flux measured from T+0.18 sec in the 15-150 keV band is 35.9 +- 1.6 ph/cm2/sec. A fit to a simple power law gives a photon index of 1.37 +- 0.05 (chi squared 75.58 for 57 d.o.f.). 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/1293340
GCN 39619 table
GRB_name GRB250306A
GCN_number 39619
Detection_method Konus-Wind Det
t_trigger 16:30:04.612 UTC
Circular_text TITLE: GCN CIRCULAR NUMBER: 39619 SUBJECT: Konus-Wind detection of GRB 250306A DATE: 25/03/07 22:30:19 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 250306A (Swift-BAT detection: Evans et al., GCN 39606; Astrosat-CZTI detection: Tembhurnikar et al., GCN 39611) triggered Konus-Wind at T0=59404.612 s UT (16:30:04.612). The burst light curve shows a double-peaked structure which starts at ~T0-0.5 s and has a total duration of ~15 s. The emission is seen up to ~3 MeV. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB250306_T59404/ As observed by Konus-Wind, the burst had a fluence of 2.32(-0.15,+0.16)x10^-5 erg/cm2, and a 64-ms peak flux, measured from T0+1.120 s, of 1.40(-0.12,+0.12)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+18.176 s) is best fit in the 20 keV - 20 MeV range by the GRB (Band) model with the following parameters: the low-energy photon index alpha = -0.94(-0.08,+0.08), the high energy photon index beta = -2.78(-0.33,+0.19), the peak energy Ep = 179(-10,+11) keV (chi2 = 84/97 dof). The spectrum near the maximum count rate (measured from T0+0.256 to T0+1.792 s) is best fit in the 20 keV - 20 MeV range by the GRB (Band) model with the following parameters: the low-energy photon index alpha = -0.62(-0.08,+0.09), the high energy photon index beta = -2.59(-0.13,+0.10), the peak energy Ep = 217(-13,+14) keV (chi2 = 55/54 dof). All the quoted errors are at the 68% confidence level. All the quoted values are preliminary.