[vsnet-grb-info 12319] GRB 120821A: Swift/XRT observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  13699
SUBJECT: GRB 120821A: Swift/XRT observations
DATE:    12/08/22 12:05:46 GMT
FROM:    Paolo D'Avanzo at INAF-OAB  <paolo.davanzo at brera.inaf.it>

P. D'Avanzo, A. Melandri, S. Campana (INAF-OAB) report on behalf of the
Swift team:

The Swift XRT observed the error circle of the INTEGRAL-detected GRB
120821A (Mereghetti et al, GCN Circ. 13696) from 15.2 to 17.2 ks after the
trigger. The data comprise 2.0 ks of Photon Counting (PC) mode data. No
clear afterglow candidate is detected. We note however the presence of a
very faint and low-significance source within the INTEGRAL error circle
(Mereghetti et al, GCN Circ. 13696) at the following position: RA, Dec
=255.25762, -40.51365 which is equivalent to:

RA (J2000): 17h 01m 01.83s
Dec (J2000): -40d 30' 49.1"

with an uncertainty of 6.7 arcsec (radius, 90% confidence).

The source has a count rate of (4.5 +/- 2.1) x 10^-3 cts/s. This
corresponds to an observed 0.3-10 keV flux of (2.7 +/- 1.2) x 10^-13
erg/cm2/s (assuming a typical GRB spectrum with photon spectral index of
2). If we consider the Galactic absorption in this direction (1.1 x 10^22
cm^-2; Kalberla et al. 2005) this corresponds to an unabsorbed flux of
(5.5 +/- 2.5) x 10^-12 erg/cm2/s. Given the limited statistics, it is not
possible to determine whether the source is fading.