TITLE:   GCN CIRCULAR
NUMBER:  44458
SUBJECT: IPN triangulation of GRB 260428A
DATE:    26/05/04 15:04:29 GMT
FROM:    Anna Ridnaia at Ioffe Institute <ridnaia@mail.ioffe.ru>

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,

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

C. Wang (IHEP), S. Xiong (IHEP), S. Zhang (IHEP),
J. Wei (NAOC),  B. Cordier (CEA) on behalf of the SVOM-GRM 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 short-duration GRB 260428A
(Fermi-GBM detection: Fermi GBM team, GCN Circ. 44415;
AstroSat-CZTI detection: Goyal et al., GCN Circ. 44421;
GECAM-B detection: Wang et al., GCN Circ. 44423;
SVOM/GRM observation: Wang et al., GCN Circ. 44424)
was detected by Fermi (GBM), Konus-Wind, AstroSat (CZTI),
GECAM-B, SVOM (GRM), and Mars-Odyssey (HEND) 
at about 51636 s UT (14:20:36).

We have triangulated it to a preliminary, 3 sigma error box
whose coordinates are:
---------------------------------------------
  RA(2000), deg                 Dec(2000), deg
 ---------------------------------------------
 Center:
  283.386 (18h 53m 33s)  +0.365 ( +0d 21' 53")
 Corners:
  283.274 (18h 53m 06s)  +1.978 ( +1d 58' 41")
  283.221 (18h 52m 53s)  +2.065 ( +2d 03' 56")
  283.504 (18h 54m 01s)  -1.335 ( -1d 20' 06")
  283.558 (18h 54m 14s)  -1.435 ( -1d 26' 07")
 ---------------------------------------------
The error box area is 561 sq. arcmin, and its maximum
dimension is 3.5 deg (the minimum one is 3 arcmin).
The Sun distance was 111 deg.

A triangulation map and HEALPix FITS file are posted at
http://www.ioffe.ru/LEA/GRBs/GRB260428_T51639/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.