GCN Circular 41050
Subject
IPN triangulation of GRB 250704B (short/hard, consistent with EP 250704a)
Event
Date
2025-07-09T15:26:13Z (4 days 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,
Y. Zhang, C. Wang, S. Xiong, J. Wei, and B. Cordier
on behalf of the SVOM-GRM team,
C. Wang, S. Xiong, S. Zheng and Y. Zhang,
on behalf of the Insight-HXMT 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, short-duration GRB 250704B
(SVOM/GRM observation: Wang et al., GCN 40940;
Konus-Wind detection: Frederiks et al., GCN 40972;
Insight-HXMT detection: Wang et al., GCN 40978;
CALET/CGBM detection: Shimizu et al., GCN 41025)
was detected by SVOM(GRB), Konus-Wind, Insight (HXMT),
CALET (CGBM), and Mars-Odyssey (HEND) at about 29791 s UT (08:16:31).
We have triangulated it to a preliminary, 3 sigma error box
whose coordinates are:
---------------------------------------------
RA(2000), deg Dec(2000), deg
---------------------------------------------
Center:
300.880 (20h 03m 31s) +12.053 (+12d 03' 11")
Corners:
300.926 (20h 03m 42s) +12.075 (+12d 04' 30")
300.872 (20h 03m 29s) +12.109 (+12d 06' 33")
300.834 (20h 03m 20s) +12.031 (+12d 01' 52")
300.888 (20h 03m 33s) +11.997 (+11d 59' 49")
---------------------------------------------
The error box area is 19 sq. arcmin, and its maximum
dimension is 7 arcmin (the minimum one is 4 arcmin).
The Sun distance was 141 deg.
This localization may be improved.
The position of EP250704a (Li et al., GCNs 40941, 40956)
is consistent with the IPN localization, supporting
the association of the GRB and EP 250704a.
A triangulation map and HEALPix FITS file are posted at
http://www.ioffe.ru/LEA/GRBs/GRB250704_T29791/IPN/
The HEALPix triangulation map is the multi-order HEALPix in units of
probability density.