TITLE:   GCN CIRCULAR
NUMBER:  31877
SUBJECT: IPN triangulation of GRB 220403C
DATE:    22/04/11 21:09:21 GMT
FROM:    Dmitry Svinkin at Ioffe Institute  <svinkin@mail.ioffe.ru>

A.S. Kozyrev, D.V. Golovin, M.L. Litvak, I.G. Mitrofanov, and A.B. Sanin
on behalf of the MGNS/BepiColombo and HEND/Mars Odyssey teams,

J. Benkhoff on behalf of the BepiColombo team,

D. Svinkin, 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,

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, R. Starr,
and A.S. Gardner on behalf of the GRS-Odyssey GRB team, report:

The bright, long-duration GRB 220403C
(Swift/BAT-GUANO detection: Tohuvavohu et al. GCN Circ. 31824)
was detected by Konus-Wind, Fermi (GBM in the trigger 670673407), INTEGRAL 
(SPI-ACS), BepiColombo (MGNS), Mars-Odyssey (HEND),
Swift (BAT), CALET (CGBM), and ISS (ASIM)
at about 36830 s UT (10:13:50).
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:
    17.570 (01h 10m 17s) -56.225 (-56d 13' 31")
  Corners:
    17.411 (01h 09m 39s) -56.347 (-56d 20' 48")
    17.548 (01h 10m 12s) -56.349 (-56d 20' 56")
    17.728 (01h 10m 55s) -56.104 (-56d 06' 13")
    17.591 (01h 10m 22s) -56.101 (-56d 06' 05")
  ---------------------------------------------
The error box area is 68 sq. arcmin, and its maximum
dimension is 18 arcmin (the minimum one is 4.3 arcmin).
The Sun distance was 62 deg.

This box may be improved.

The box is inconsistent with the GRB 220403A Konus-GBM annulus centered at
RA(2000)=355.082 deg (23h 40m 20s) Dec(2000)=-4.166 deg (-4d 09' 56"),
whose radius is 23.380 +/- 23.380 deg (3 sigma).
Thus GRB 220403C and GRB 220403A (GCN 31818) are unrelated.

A triangulation map is posted at
http://www.ioffe.ru/LEA/GRBs/GRB220403_T36829/IPN/

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