GRB 250929A
GCN Circular 42029
Subject
Fermi GRB 250929A: Global MASTER-Net observations report
Date
2025-09-29T20:31:09Z (4 days ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>
Via
email
V.Lipunov, E.Gorbovskoy, A.Kuznetsov, K.Zhirkov, I.Panchenko, N.Tiurina, P.Balanutsa, V.Topolev, D.Vlasenko,
G.Antipov, A.Sankovich, Yu.Tselik, 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.Sosnovskij (CrAO),
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 250929A ( Fermi GBM team, GCN 42028) errorbox 364 sec after notice time and 395 sec after trigger time at 2025-09-29 20:12:42 UT, with upper limit up to 18.9 mag. The observations began at zenith distance = 53 deg. The sun altitude is -42.7 deg.
The galactic latitude b = -45 deg., longitude l = 273 deg.
Real time updated cover map and OT discovered available here:
https://master.sai.msu.ru/site/master2/observ.php?id=3002549
We obtain a following upper limits.
Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________
425 | 2025-09-29 20:12:42 | MASTER-SAAO | (02h 49m 40.43s , -53d 58m 56.7s) | C | 60 | 18.9 |
425 | 2025-09-29 20:12:42 | MASTER-SAAO | (02h 52m 46.96s , -54d 14m 04.8s) | C | 60 | 18.9 |
Filter C is a clear (unfiltred) band.
The observation and reduction will continue.
The message may be cited.
GCN Circular 42028
Subject
GRB 250929A: Fermi GBM Final Real-time Localization
Date
2025-09-29T20:16:36Z (4 days 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 20:06:07 UT on 29 Sep 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250929A (trigger 780869172.178268 / 250929838).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 58.2, Dec = -60.2 (J2000 degrees, equivalent to J2000 03h 52m, -60d 12'), with a statistical uncertainty of 11.5 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/bn250929838/quicklook/glg_skymap_all_bn250929838.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/bn250929838/quicklook/glg_healpix_all_bn250929838.fit
The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250929838/quicklook/glg_lc_medres34_bn250929838.gif