TITLE:   GCN CIRCULAR
NUMBER:  20859
SUBJECT: IPN Triangulation of GRB 170311B (long/very intense)
DATE:    17/03/13 18:56:23 GMT
FROM:    Dmitry Svinkin at Ioffe Institute  <svinkin@mail.ioffe.ru>

K. Hurley, on behalf of the IPN,

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

D. Svinkin, S. Golenetskii, R. Aptekar, D. Frederiks, A. Kozlova,
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:

A long-duration, very intense GRB 170311B
has been detected by Konus-Wind, Mars-Odyssey (HEND),
and Swift (BAT), so far, at about 49490 s UT (13:44:50).
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:
   354.919 (23h 39m 40s) +31.187 (+31d 11' 14")
  Corners:
   355.382 (23h 41m 32s) +31.782 (+31d 46' 54")
   355.104 (23h 40m 25s) +31.806 (+31d 48' 21")
   354.474 (23h 37m 54s) +30.587 (+30d 35' 13")
   354.747 (23h 38m 59s) +30.567 (+30d 34' 01")
  ---------------------------------------------
The error box area is 1076 sq. arcmin, and its maximum
dimension is 1.42 deg (the minimum one is 13.4 arcmin).
The Sun distance was 34 deg.

This box may be improved.

A triangulation map is posted at
http://www.ioffe.ru/LEA/GRBs/GRB170311_T49504/IPN

The time history and spectrum will be given in forthcoming GCN Circulars.