[vsnet-grb-info 12365] GRB 120908A: Swift Observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  13740
SUBJECT: GRB 120908A: Swift Observations
DATE:    12/09/10 14:55:07 GMT
FROM:    Stefan Immler at NASA/GSFC  <stefan.m.immler at nasa.gov>

S. Immler (CRESST/GSFC/UMD), C. Pagani (U. Leicester), and
A. A. Breeveld (MSSL-UCL) report on behalf of the Swift team:

Swift began a Target of Opportunity observation of the MAXI/GSC
discovered burst GRB 120908A (Morii et al. GCN 13731) at 2012-09-09
13:41:43 UT.

We have analyzed 3.7 ks of XRT data, starting ~54 ks after the MAXI
trigger. The data are entirely in Photon Counting mode, centered on
the MAXI position and partially covering the MAXI error region.
No new source is detected in the XRT data. The 3-sigma upper limit
is 0.004 counts/sec which is 2.4e-13 erg cm^-2 s^-1 for a typical GRB
spectrum.

The Swift/UVOT began settled observations of the field 54.4 ks after
the MAXI trigger (Morii et al., GCN Circ. 13731). No optical afterglow
consistent with the MAXI position given in that circular is detected
in the initial UVOT exposures. Preliminary 3-sigma upper limits using
the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc.
1358, 373) for the initial exposures are:

Filter         T_start(s)   T_stop(s)      Exp(s)         Mag

white            54383        66117         2345         >21.7

The magnitude in the table is not corrected for the Galactic
extinction due to the reddening of E(B-V) = 0.23 in the direction of
the burst (Schlegel et al. 1998).