TITLE:   GCN CIRCULAR
NUMBER:  22679
SUBJECT: IPN Triangulation of GRB 180427A
DATE:    18/04/28 15:35:23 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,

V. Connaughton, M. S. Briggs, C. Meegan, V. Pelassa,
and A. Goldstein, 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, 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 GRB 180427A (Bissaldi, GCN Circ. 22678)
was detected by Fermi (GBM; trigger 546518228), Konus-Wind, Mars-Odyssey 
(HEND), INTEGRAL (SPI-ACS), and Swift (BAT) at about 38223 s UT (10:37:03).
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:
   271.012 (18h 04m 03s) +68.454 (+68d 27' 14")
  Corners:
   277.258 (18h 29m 02s) +68.858 (+68d 51' 30")
   265.504 (17h 42m 01s) +67.232 (+67d 13' 56")
   265.042 (17h 40m 10s) +67.831 (+67d 49' 51")
   277.094 (18h 28m 23s) +69.480 (+69d 28' 49")
  ---------------------------------------------
The error box area is 2.88 sq. deg, and its maximum
dimension is 4.82 deg (the minimum one is 36.96 arcmin).
The Sun distance was 86 deg.

This box may be improved.

A triangulation map is posted at
http://www.ioffe.ru/LEA/GRBs/GRB180427_T38222/IPN

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