TITLE:   GCN CIRCULAR
NUMBER:  17112
SUBJECT: IPN Triangulation of GRB 141121A (initial episode)
DATE:    14/11/28 20:00:34 GMT
FROM:    Dmitry Svinkin at Ioffe Institute  <svinkin@mail.ioffe.ru>

K. Hurley and J. Goldsten, on behalf of the MESSENGER NS GRB team,

S. Golenetskii, R. Aptekar, V. Pal'shin, D. Frederiks,
D. Svinkin, and T. Cline on behalf of the Konus-Wind team,

S. Barthelmy, J. Cummings, N. Gehrels, H. Krimm, and D. Palmer,
on behalf of the Swift-BAT team, and

A. von Kienlin, X. Zhang, A. Rau, V. Savchenko, E. Bozzo, and C.
Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team, report:

The possible initial emission episode of GRB 141121A reported by
Konus-Wind (Golenetskii et al., GCN Circ. 17108) has been also observed 
by INTEGRAL (SPI-ACS) and MESSENGER (GRNS) at about 13083 s UT 
(03:38:03; =T0(BAT)-760 s), so far.

We have triangulated it to a INTEGRAL-MESSENGER annulus centered at 
RA(2000)=46.543 deg (03h 06m 10s)  Dec(2000)=+16.630 deg (+16d 37' 49"), 
whose radius is 71.291 +/- 0.356 deg (3 sigma).

The distance between the Swift-XRT position of GRB 141121A (Evans et 
al., GCN Circ. 17080) and the central line of the annulus is 32 arcsec, 
which strengthen the association of the episode with GRB 141121A.

A triangulation map is posted at
http://www.ioffe.ru/LEA/GRBs/GRB141121A/IPN/