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GCN Circular 31177

Subject
IPN triangulation of GRB 211204C
Date
2021-12-07T04:14:27Z (3 years ago)
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 teams,

K. Hurley, on behalf of the IPN,

A. Ridnaia, D. Frederiks, D. Svinkin, 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 long-duration GRB 211204C
(Fermi GBM detection: Fermi GBM team, GCN 31171Loading...
 
 ;
GECAM detection: Zhang et al., GCN 31173Loading...
 
 ;
Swift/BAT-GUANO detection: DeLaunay et al., GCN 31174Loading...
 
 )
was detected by Fermi (GBM trigger 660346625), Konus-Wind,
INTEGRAL (SPI-ACS), Mars-Odyssey (HEND), GECAM-B (GRD),
and Swift (BAT) at about 77820 s UT (21:37:00).
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:
  338.952 (22h 35m 48s) +52.171 (+52d 10' 15")
 Corners:
  338.910 (22h 35m 38s) +49.891 (+49d 53' 29")
  338.806 (22h 35m 14s) +49.979 (+49d 58' 43")
  339.068 (22h 36m 16s) +54.400 (+54d 24' 01")
  339.176 (22h 36m 42s) +54.316 (+54d 18' 59")
 ---------------------------------------------
The error box area is 1084 sq. armin, and its maximum
dimension is 4.5 deg (the minimum one is 4.1 arcmin).
The Sun distance was 105 deg.

This box may be improved.

The IPN localization is consistent with, but reduces the area of, the
Fermi GBM on-ground calculated localization (GCN Circ. 31171Loading...
 
 ) and
GECAM-B automatic on-ground localization (GCN Circ. 31173Loading...
 
 ).

A triangulation map is posted at
http://www.ioffe.ru/LEA/GRBs/GRB211204_T77823/IPN

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