TITLE:   GCN CIRCULAR
NUMBER:  29348
SUBJECT: IPN triangulation of GRB 210121A
DATE:    21/01/23 22:15:41 GMT
FROM:    Dmitry Svinkin at Ioffe Institute  <svinkin@mail.ioffe.ru>

K. Hurley, on behalf of the IPN,

I. G. Mitrofanov, D. V. Golovin, A. S. Kozyrev, M. L. Litvak,
and A. B. Sanin, on behalf of the HEND-Odyssey GRB team,

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

A. von Kienlin, X. Zhang, A. Rau, V. Savchenko, E. Bozzo,
and C. Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team,

and

W. Boynton, C. Fellows, K. Harshman, H. Enos, and R. Starr,
on behalf of the GRS-Odyssey GRB team, report:

The long-duration, bright GRB 210121A
(Insight-HXMT/HE detection: Xue et al., GCN Circ. 29346
GECAM detection: Peng et al., GCN Circ. 29347)
has been detected by Konus-Wind, Mars-Odyssey (HEND),
INTEGRAL (SPI-ACS), Insight (HXMT/HE), and GECAM, so far,
at about 67309 s UT (18:41:49).

We have triangulated it to a preliminary, 3 sigma error box
whose coordinates are:
---------------------------------------------
   RA(2000), deg                 Dec(2000), deg
  ---------------------------------------------
  Center:
    16.981 (01h 07m 55s) -46.401 (-46d 24' 04")
  Corners:
    17.388 (01h 09m 33s) -46.452 (-46d 27' 06")
    17.369 (01h 09m 29s) -46.539 (-46d 32' 20")
    16.575 (01h 06m 18s) -46.348 (-46d 20' 54")
    16.595 (01h 06m 23s) -46.261 (-46d 15' 40")
  ---------------------------------------------
The error box area is 181 sq. arcmin, and its maximum
dimension is 36 arcmin (the minimum one is 5 arcmin).
The Sun distance was 64 deg.

This box may be improved.

A triangulation map is posted at
http://www.ioffe.ru/LEA/GRBs/GRB210121_T67306/IPN

The Konus-Wind time history and spectrum will be given in a forthcoming
GCN Circular.