GRB 250620
GCN Circular 40809
Subject
IPN triangulation of GRB 250620С (long/bright)
Date
2025-06-22T09:58:12Z (3 days ago)
From
Dmitry Svinkin at Ioffe Institute <dmitrysvinkin@gmail.com>
Via
Web form
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
S. Barthelmy, J. Cummings, H. Krimm, D. Palmer, A. Tohuvavohu,
and J. DeLaunay on behalf of the Swift-BAT team, report:
The bright long-duration GRB 250620C
(Fermi-GBM detection: The Fermi GBM team, GCN 40794;
Mukherjee, GCN 40799;
SVOM-GRM detection: Wang et al., GCN 40807)
was detected by Fermi (GBM trigger 772128434), Swift (BAT),
Konus-Wind, and SVOM (GRM) at about 58030 s UT (16:07:10).
The burst was outside the coded field of view of the BAT.
We have triangulated it to a preliminary, 3 sigma error box
whose area is 17.6 sq. deg, and its maximum
dimension is 25.5 deg (the minimum one is 51.0 arcmin).
The Sun distance was ~50 deg.
This localization may be improved.
The IPN localization is consistent with, but reduces the area of,
the Fermi-GBM (GCN 40794) and BALROG
(https://grb.mpe.mpg.de/grb/GRB250620672/?data_version=tte_v00) localizations.
A triangulation map and HEALPix FITS file are posted at
http://www.ioffe.ru/LEA/GRBs/GRB250620_T58026/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.