TITLE:   GCN CIRCULAR
NUMBER:  29090
SUBJECT: IPN triangulation of GRB 201218A
DATE:    20/12/19 01:12:10 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, R. Aptekar, D. Frederiks, A. Ridnaia,
and T. Cline on behalf of the Konus-Wind team,

S. Barthelmy, J. Cummings, H. Krimm, and D. Palmer,
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, very bright GRB 201218A
(Fermi-GBM detection: The Fermi GBM team, GCN Circ. 29081;
BALROG localization: Biltzinger et al., GCN Circ. 29083)
has been detected by Fermi (GBM trigger 629957660),
Konus-Wind,  Mars-Odyssey (HEND), and Swift (BAT),
so far, at about 15256 s UT (04:14:16).
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:
   288.498 (19h 13m 59s) +28.356 (+28d 21' 23")
  Corners:
   288.470 (19h 13m 53s) +28.144 (+28d 08' 38")
   288.400 (19h 13m 36s) +28.556 (+28d 33' 23")
   288.526 (19h 14m 06s) +28.569 (+28d 34' 08")
   288.596 (19h 14m 23s) +28.156 (+28d 09' 22")
  ---------------------------------------------
The error box area is 168 sq. arcmin, and its maximum
dimension is 26 arcmin (the minimum one is 6.7 arcmin).
The Sun distance was 56 deg.

The IPN localization is consistent with, but reduces the area of, the 
Fermi RoboBA and BALROG localizations (GCN Circ. 29081 and 29083).

A triangulation map is posted at
http://www.ioffe.ru/LEA/GRBs/GRB201218_T15255/IPN/

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