GCN Circular 41041
Subject
IPN triangulation of GRB 250706C (consistent with the GRB 250706B)
Event
Date
2025-07-08T19:30:06Z (17 hours ago)
From
Anna Ridnaia at Ioffe Institute <ridnaia@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,
A. Ridnaia, D. Frederiks, A. Lysenko, D. Svinkin,
and T. Cline on behalf of the Konus-Wind team,
E. Burns on behalf of the IPN,
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 very bright, long-duration GRB 250706C
(Konus-Wind detection: Frederiks et al., GCNs 41013, 41027;
Fermi-LAT detection: Longo et al., GCN 41019)
was detected by Konus-Wind and Mars-Odyssey (HEND)
at about 60322 s UT (16:45:22), ~1200 s before GRB 250706B
(SVOM detection: Palmerio et al, GCNs 40989, 41026)
We have triangulated it to a Konus-HEND annulus centered at
RA(2000)=342.841 deg (22h 51m 22s) Dec(2000)=-8.288 deg (-8d 17' 19"),
whose radius is 63.671 +/- 0.024 deg (3 sigma).
This localization may be improved.
The SVOM/ECLAIRs source localization reported for GRB 250706B (GCN 40989)
is consistent with the Konus-HEND annulus, the Konus-Wind ecliptic latitude
response and the Fermi-LAT position (GCN 41019), indicating that GRB 250706B and
GRB 250706C are distinct emission episodes of the same GRB.
A triangulation map and HEALPix FITS file are posted at
http://www.ioffe.ru/LEA/GRBs/GRB250706_T60322/IPN/
The HEALPix triangulation map is the multi-order HEALPix in units of
probability density.