TITLE:   GCN CIRCULAR
NUMBER:  30002
SUBJECT: IPN triangulation of GRB 210511B
DATE:    21/05/12 18:15:02 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,

and

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

The long-duration GRB 210511B
(Fermi-GBM detection: The Fermi GBM team, GCN Circ. 29988;
Bissaldi and Meegan, GCN Circ. 29996;
BALROG localization: Kunzweiler et al., GCN Circ. 29989;
GECAM detection: Cai et al., GCN Circ. 29990;
AGILE detection: Ursi et al., GCN Circ. 29991)
was detected by Fermi (GBM trigger 642425204), Konus-Wind,
Mars-Odyssey (HEND), INTEGRAL (SPI-ACS), AGILE and GECAM-B
at about 41199 s UT (11:26:39).

We have triangulated it to a preliminary, 3 sigma error box
whose coordinates are:
  ---------------------------------------------
   RA(2000), deg                 Dec(2000), deg
  ---------------------------------------------
  Center:
   312.914 (20h 51m 39s) +58.375 (+58d 22' 31")
  Corners:
   306.385 (20h 25m 33s) +59.894 (+59d 53' 39")
   306.250 (20h 25m 00s) +60.029 (+60d 01' 45")
   318.903 (21h 15m 37s) +56.519 (+56d 31' 10")
   318.984 (21h 15m 56s) +56.371 (+56d 22' 16")
  ---------------------------------------------
The error box area is 2687 sq. arcmin, and its maximum
dimension is 7.6 deg (the minimum one is 6.0 arcmin).
The Sun distance was 75 deg.

This box may be improved.

This error box is consistent with, but reduces the areas of, the Fermi 
(RoboBA and BALROG), and GECAM localizations.

A triangulation map is posted at
http://www.ioffe.ru/LEA/GRBs/GRB210511_T41201/IPN

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