TITLE:   GCN CIRCULAR
NUMBER:  30076
SUBJECT: IPN triangulation of GRB 210524A
DATE:    21/05/25 10:03:18 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,
A. Lysenko, and T. Cline on behalf of the Konus-Wind team,

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

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

The intense, long-duration GRB 210524A
(Fermi-GBM detection: The Fermi GBM team, GCN Circ. 30071;
BALROG localization: Biltzinger et al., GCN Circ. 30073)
was detected by Fermi (GBM trigger 643525204), Konus-Wind,
Mars-Odyssey (HEND), INTEGRAL (SPI-ACS), and Swift-BAT
at about 17999 s UT (04:59:59).
The burst was outside the coded field of view of the BAT.

We have triangulated it to a preliminary, 3 sigma error box
whose coordinates are:
  ---------------------------------------------
   RA(2000), deg                 Dec(2000), deg
  ---------------------------------------------
  Center:
   343.564 (22h 54m 15s) -46.672 (-46d 40' 19")
  Corners:
   342.645 (22h 50m 35s) -49.867 (-49d 52' 00")
   344.262 (22h 57m 03s) -43.354 (-43d 21' 13")
   344.203 (22h 56m 49s) -43.132 (-43d 07' 56")
   342.607 (22h 50m 26s) -49.680 (-49d 40' 48")
  ---------------------------------------------
The error box area is 1584 sq. arcmin, and its maximum
dimension is 6.8 deg (the minimum one is 4 arcmin).
The Sun distance was 95 deg.

This box may be improved.

The IPN localization is consistent with, but reduces the area of, the
Fermi RoboBA and BALROG localizations (GCN Circ. 30071 and 30073).

A triangulation map is posted at
http://www.ioffe.ru/LEA/GRBs/GRB210524_T18010/IPN/

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