TITLE:   GCN CIRCULAR
NUMBER:  21138
SUBJECT: IPN Triangulation of GRB 170522A
DATE:    17/05/25 10:46:13 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 170522A
(Fermi-GBM detection: Stanbro and Meegan, GCN Circ. 21126;
Fermi-LAT detection: Arimoto and Racusin, GCN Circ. 21127;
Konus-Wind observation: Frederiks et al., GCN Circ. 21129)
was detected by Fermi (GBM trigger 517160740), Konus-Wind,
INTEGRAL (SPI-ACS), Mars-Odyssey (HEND), and Swift (BAT),
at about 56735 s UT (15:45:35).
The burst was outside the coded field of view of the BAT.

We have triangulated it to a GBM-HEND annulus centered at 
RA(2000)=80.195 deg (05h 20m 47s) Dec(2000)=+23.945 deg (+23d 56' 40"), 
whose radius is 53.106 +/- 0.070 deg (3 sigma).

The LAT position reported by Arimoto and Racusin (GCN Circ. 21127)
is consistent with the annulus. The annulus combined with
the LAT (90 % containment, statistical-only) error circle
gives the following error box:
---------------------------------------------
  RA(2000), deg  Dec(2000), deg
---------------------------------------------
Center:
     139.1949    +25.6971
Corners:
     139.1335    +25.7084
     139.2170    +25.5157
     139.2562    +25.6856
     139.2950    +25.8556
---------------------------------------------
The error box area is 101.5 sq. arcmin
(a factor of 4 smaller that that of LAT error circle).

This box may be improved.

None of the Swift-XRT sources reported by Mingo et al. (GCN Circ. 21133)
are consistent with the box, and only Source 1 is consistent
with the annulus.

A triangulation map is posted at
http://www.ioffe.ru/LEA/GRBs/GRB170522_T56735/IPN