GRB 250331E
GCN Circular 39988
Subject
GRB 250331E: Fermi GBM Final Real-time Localization
Date
2025-03-31T22:57:04Z (2 months ago)
From
Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply@GIOC.nsstc.nasa.gov>
Via
email
The Fermi GBM team reports the detection of a likely LONG GRB
At 22:46:32 UT on 31 Mar 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250331E (trigger 765153997.78765 / 250331949).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 196.6, Dec = -27.7 (J2000 degrees, equivalent to J2000 13h 06m, -27d 41'), with a statistical uncertainty of 14.0 degrees.
The angle from the Fermi LAT boresight is 73.0 degrees.
The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250331949/quicklook/glg_skymap_all_bn250331949.png
The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250331949/quicklook/glg_healpix_all_bn250331949.fit
The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250331949/quicklook/glg_lc_medres34_bn250331949.gif
GCN Circular 39991
Subject
Fermi GRB 250331E: Global MASTER-Net observations report
Date
2025-04-01T01:16:06Z (2 months ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>
Via
email
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) started inspect of the Fermi GRB 250331E ( Fermi GBM team, GCN 39988) errorbox 4 sec after trigger time at 2025-03-31 22:46:37 UT, with upper limit up to 19.3 mag. The observations began at zenith distance = 12 deg. The sun altitude is -62.4 deg.
The galactic latitude b = 35 deg., longitude l = 308 deg.
Real time updated cover map and OT discovered available here:
https://master.sai.msu.ru/site/master2/observ.php?id=2829592
We obtain a following upper limits.
Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________
35 | 2025-03-31 22:46:37 | MASTER-SAAO | (12h 57m 48.00s , -20d 04m 42.7s) | C | 60 | 19.0 |
114 | 2025-03-31 22:47:56 | MASTER-SAAO | (13h 06m 14.94s , -20d 06m 25.5s) | C | 60 | 19.1 |
1229 | 2025-03-31 23:06:32 | MASTER-SAAO | (13h 25m 08.68s , -32d 04m 39.4s) | C | 60 | 19.0 |
1388 | 2025-03-31 23:09:10 | MASTER-SAAO | (13h 34m 31.38s , -32d 07m 08.5s) | C | 60 | 19.2 |
2434 | 2025-03-31 23:26:37 | MASTER-SAAO | (13h 25m 13.32s , -32d 05m 29.0s) | C | 60 | 19.2 |
2593 | 2025-03-31 23:29:15 | MASTER-SAAO | (14h 07m 32.41s , -36d 55m 59.7s) | C | 60 | 19.3 |
3468 | 2025-03-31 23:43:50 | MASTER-SAAO | (14h 07m 42.96s , -36d 54m 45.6s) | C | 60 | 19.1 |
4282 | 2025-03-31 23:57:24 | MASTER-SAAO | (14h 07m 44.51s , -36d 53m 28.5s) | C | 60 | 19.1 |
5764 | 2025-04-01 00:22:06 | MASTER-SAAO | (14h 07m 53.30s , -36d 53m 01.5s) | C | 60 | 19.1 |
6499 | 2025-04-01 00:34:21 | MASTER-SAAO | (14h 07m 57.57s , -36d 54m 12.1s) | C | 60 | 19.2 |
7157 | 2025-04-01 00:45:19 | MASTER-SAAO | (14h 07m 59.18s , -36d 53m 44.9s) | C | 60 | 19.1 |
7236 | 2025-04-01 00:46:38 | MASTER-SAAO | (13h 35m 38.73s , -27d 21m 54.8s) | C | 60 | 19.1 |
7315 | 2025-04-01 00:47:58 | MASTER-SAAO | (13h 44m 37.58s , -27d 21m 15.5s) | C | 60 | 19.3 |
7474 | 2025-04-01 00:50:36 | MASTER-SAAO | (13h 22m 32.82s , -25d 27m 53.6s) | C | 60 | 19.3 |
Filter C is a clear (unfiltred) band.
The observation and reduction will continue.
The message may be cited.
GCN Circular 40007
Subject
GRB 250331E: SVOM/GRM observation
Date
2025-04-02T08:09:11Z (2 months ago)
From
Yue Wang <m18509381757@163.com>
Via
Web form
SVOM/GRM team: Yue Wang, Chen-Wei Wang, Shi-Jie Zheng, Yue Huang, Shao-Lin Xiong, Shuang-Nan Zhang (IHEP)
SVOM/ECLAIRs team: Frédéric Daigne (IAP), Frédéric Piron (LUPM), Nicolas Dagoneau (CEA)
Report on behalf of the SVOM team:
SVOM/GRM was triggered in-flight by GRB 250331E (SVOM trigger reference: sb25033103) at 2025-03-31T22:46:35.000 (T0). This burst was also detected by Fermi/GBM (Fermi GBM Team, GCN 39988).
With the event-by-event data downloaded through the X-band ground station, the GRM light curve shows that this burst consists of single main pulse with a T90 of 12.0 +1.0/-2.0 s in the 15-5000 keV band.
In addition, ECLAIRs was taking data and did not trigger, since the position of this burst, as determined by Fermi/GBM (GCN 39988, RA: 196.6 deg, DEC: -27.7 deg, Error: 14.0 deg), is located at about 60.7 degrees from the SVOM optical axis, and outside the ECLAIRs field of view.
The SVOM/GRM light curve can be found here:
https://www.bursthub.cn//admin/static/svgrb250331E.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/GRM point of contact for this burst is: Yue Wang (IHEP) (yuewang@ihep.ac.cn)