[vsnet-grb-info 7159] GRB 081226B: Swift XRT and UVOT upper limits

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  8740
SUBJECT: GRB 081226B: Swift XRT and UVOT upper limits
DATE:    08/12/27 10:02:56 GMT
FROM:    Phil Evans at U of Leicester  <pae9 at star.le.ac.uk>

P.A. Evans (U. Leicester) and E.A. Hoversten (PSU) report on behalf of
the Swift team:

Swift observed the field of GRB 081226B (Mereghetti et al. GCN Circ
8734) for 8 ks, beginning 9.6 ks after the INTEGRAL trigger. The XRT
data (all in Photon Counting mode) contain no source in the INTEGRAL
error circle. A 3-sigma upper limit is 0.001 counts/sec which is 5.6e-14
erg cm^-2 s^-1 for a typical GRB spectrum.

Given the absence of an XRT position, the UVOT images were compared to
archival images from the Digitized Sky Survey.  No candidate afterglow
was found in the INTEGRAL error circle.  UVOT magnitude 3-sigma upper
limits are reported in the following table:

Filter   T_start   T_stop   Exp(s)  Mag (3-sigma upper limit)
-------------------------------------------------------------
WHITE     9744     22737    1414        > 22.24
v         9621     27619    1940        > 20.48
b         9720     21824    1414        > 21.06
u         9694     16082     352        > 20.34
uvw1     10019     15877     313        > 20.20
uvm2     15472     28224     787        > 20.75
uvw2     10812     23271     932        > 21.27

The quoted upper limits have not been corrected for the expected
Galactic extinction along the line of sight of E_(B-V) = 0.01 mag.
All photometry is on the UVOT photometric system described in Poole et
al. (2008, MNRAS, 383, 627).

This circular is an official product of the Swift XRT and UVOT teams.