GRB 250523A
GCN Circular 40538
Subject
GRB 250523A: Fermi GBM Final Real-time Localization
Date
2025-05-23T14:36:55Z (6 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 14:26:23 UT on 23 May 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250523A (trigger 769703188.305002 / 250523602).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 52.9, Dec = 55.2 (J2000 degrees, equivalent to J2000 03h 31m, 55d 12'), with a statistical uncertainty of 3.0 degrees.
The angle from the Fermi LAT boresight is 38.0 degrees.
The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250523602/quicklook/glg_skymap_all_bn250523602.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/bn250523602/quicklook/glg_healpix_all_bn250523602.fit
The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250523602/quicklook/glg_lc_medres34_bn250523602.gif
GCN Circular 40539
Subject
GRB 250523A: BALROG localization (Fermi Trigger 769703188 / GRB 250523602)
Date
2025-05-23T14:53:57Z (6 days ago)
From
Jochen Greiner at MPE <jcgrog@mpe.mpg.de>
Via
email
T. Preis (University of Innsbruck) & J. Greiner (MPE Garching) report:
The public trigdat data of the Fermi Gamma-ray Burst Monitor (GBM) trigger
769703188 at 14:26:23 on 23 May 2025 were automatically fitted for spectrum
and sky location with BALROG (Burgess et al. 2018, MNRAS 476, 1427;
Berlato et al. 2019, ApJ 873, 60).
The best-fit position is:
RA(2000.0) = 64.4 deg
Decl.(2000.0) = 53.7 deg
The 1 sigma statistical error radius is 2.9 deg.
We estimate an additional systematic error of 1 deg.
Further details are available at:
https://grb.mpe.mpg.de/grb/GRB250523602/
The Healpix map can be downloaded from:
https://grb.mpe.mpg.de/grb/GRB250523602/healpix
The location parameters are available as JSON at:
https://grb.mpe.mpg.de/grb/GRB250523602/json
GCN Circular 40544
Subject
Fermi GRB 250523A: Global MASTER-Net observations report
Date
2025-05-23T20:31:57Z (6 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-Kislovodsk robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) started inspect of the Fermi GRB 250523A ( Fermi GBM team, GCN 40538) errorbox 21017 sec after notice time and 21056 sec after trigger time at 2025-05-23 20:17:20 UT, with upper limit up to 17.1 mag. The observations began at zenith distance = 81 deg. The sun altitude is -25.3 deg.
The galactic latitude b = -0 deg., longitude l = 145 deg.
Real time updated cover map and OT discovered available here:
https://master.sai.msu.ru/site/master2/observ.php?id=2879253
We obtain a following upper limits.
Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________
21087 | 2025-05-23 20:17:20 | MASTER-Kislovodsk | (03h 30m 46.09s , +56d 01m 35.6s) | C | 60 | 17.1 |
21175 | 2025-05-23 20:18:48 | MASTER-Kislovodsk | (03h 45m 14.18s , +56d 02m 05.0s) | C | 60 | 17.0 |
21462 | 2025-05-23 20:23:35 | MASTER-Kislovodsk | (03h 02m 54.34s , +56d 12m 15.7s) | C | 60 | 17.1 |
21545 | 2025-05-23 20:24:58 | MASTER-Kislovodsk | (03h 17m 09.58s , +56d 11m 13.2s) | C | 60 | 17.1 |
Filter C is a clear (unfiltred) band.
The observation and reduction will continue.
The message may be cited.