TITLE:   GCN CIRCULAR
NUMBER:  39013
SUBJECT: Improved IPN triangulation of GRB 250107C
DATE:    25/01/22 15:22:14 GMT
FROM:    Dmitry Svinkin at Ioffe Institute <svinkin@mail.ioffe.ru>

A.S. Kozyrev, D.V. Golovin, M.L. Litvak, I.G. Mitrofanov, and A.B. Sanin
on behalf of the MGNS/BepiColombo and the HEND/Mars-Odyssey teams,

J. Benkhoff on behalf of the BepiColombo team,

D. Svinkin, D. Frederiks, A. Lysenko, A. Ridnaia,
and T. Cline on behalf of the Konus-Wind team,

Y. Zhang, C. Wang, S. Xiong, J. Wei, and B. Cordier
on behalf of the SVOM-GRM team,

A. Goldstein, M. S. Briggs, C. Wilson-Hodge,
and E. Burns on behalf of the Fermi GBM team,

S. Barthelmy, J. Cummings, H. Krimm, D. Palmer, and A. Tohuvavohu
on behalf of the Swift-BAT 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 long-duration GRB 250107C
(SVOM-GRM and GECAM-B detections: Xue et al., GCN 38870;
initial IPN triangulation: Svinkin et al., GCN 38879;
Konus-Wind detection: Frederiks et al., GCN 38895;
CALET-GBM detection: Yoshida et al., GCN 38896)
was detected by Konus-Wind, SVOM (GRM), GECAM-B, CALET (GBM),
and BepiColombo (MGNS) at about 67936 s UT (18:52:16).

We have triangulated it to a preliminary, 3 sigma error box
whose coordinates are:
 -------------------------------
  RA(2000), deg   Dec(2000), deg
 -------------------------------
 Corners:
  348.940          +19.143
  344.400          +27.679
  344.615          +27.357
  348.961          +19.155
 -------------------------------
The error box area is 825 sq. arcmin, and its maximum
dimension is 10.5 deg (the minimum one is 1.4 arcmin).
The Sun distance was 70 deg.

This localization may be improved.

A triangulation map and HEALPix FITS file are posted at
http://www.ioffe.ru/LEA/GRBs/GRB250107_T67934/IPN/
The HEALPix triangulation map is the multi-order HEALPix in units of
probability density.