GCN Circular 41940
Subject
IPN triangulation of GRB 250920A (long/bright)
Event
Date
2025-09-22T16:39:14Z (2 days ago)
From
Dmitry Svinkin at Ioffe Institute <svinkin@mail.ioffe.ru>
Via
Web form
A.S. Kozyrev, D.V. Golovin, M.L. Litvak, I.G. Mitrofanov, and A.B. Sanin
on behalf of the HEND/Mars Odyssey team,
D. Svinkin, D. Frederiks, A. Lysenko, A. Ridnaia,
and T. Cline on behalf of the Konus-Wind team,
A. Goldstein, M. S. Briggs, C. Wilson-Hodge,
and E. Burns on behalf of the Fermi GBM team,
and
W. Boynton, C. Fellows, K. Harshman, H. Enos, R. Starr,
and A.S. Gardner on on behalf of the GRS-Odyssey GRB team,
report:
The bright, long-duration GRB 250920A
(Ferm-GBM detection: The Fermi GBM team, GCN 41895;
Sonawane and Smith, GCN 41918;
BALROG localization: Preis and Greiner, GCN 41896
AstroSat-CZTI detection: Harsha et al., GCN 41899;
SVOM-GRM detection: Wang et al., GCN 41912;
NuSTAR-detection: Waratkar et al., GCN 41926)
was detected by Fermi (GBM trigger 780029651), SVOM (GRM),
AstroSat (CZTI), NuSTAR, Konus-Wind, and Mars-Odyssey (HEND),
at about 10447 s UT (02:54:07).
We have triangulated it to a preliminary, 3 sigma error box
whose coordinates are:
---------------------------------------------
RA(2000), deg Dec(2000), deg
---------------------------------------------
Center:
176.909 (11h 47m 38s) +54.466 (+54d 27' 56")
Corners:
177.868 (11h 51m 28s) +54.769 (+54d 46' 07")
177.751 (11h 51m 00s) +54.775 (+54d 46' 28")
175.963 (11h 43m 51s) +54.152 (+54d 09' 06")
176.079 (11h 44m 19s) +54.148 (+54d 08' 54")
---------------------------------------------
The error box area is 168 sq. arcmin, and its maximum
dimension is 1.27 deg (the minimum one is 2.3 arcmin).
The Sun distance was 53 deg.
This localization may be improved.
A triangulation map and HEALPix FITS file are posted at
http://www.ioffe.ru/LEA/GRBs/GRB250920_T10444/IPN/
The HEALPix triangulation map is the multi-order HEALPix in units of
probability density.
The Konus-Wind time history and spectrum will be given
in a forthcoming GCN Circular.