[AAVSO-HEN] GRB 090807: Swift/UVOT Upper Limits

[grb at aavso.org]

The following is a GCN Circular circulated via the AAVSO network.
For an archive and more information on circulars visit:
http://lheawww.gsfc.nasa.gov/docs/gamcosray/legr/bacodine/gcn3_archive.html

TITLE:   GCN CIRCULAR
NUMBER:  9751
SUBJECT: GRB 090807: Swift/UVOT Upper Limits
DATE:    09/08/07 23:57:25 GMT
FROM:    Craig Swenson at PSU/Swift  <cswenson at astro.psu.edu>

C. A. Swenson (PSU) and Cannizzo (NASA/UMBC)report on behalf of the
Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 090807
164 s after the BAT trigger (Cannizzo et al., GCN Circ. 9746).
No optical afterglow consistent with the XRT position (Beardmore et al.,
GCN Circ. 9748) is detected in the initial UVOT exposures.
Preliminary 3-sigma upper limits using the UVOT photometric system
(Poole et al. 2008, MNRAS, 383, 627) for the first finding chart (FC)
exposure and subsequent exposures are:

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

white_FC           164          313          147         >21.2
u_FC               322          571          246         >20.1
white              164         1026          295         >21.1
u                  322          571          246         >20.1

The values quoted above are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.18 in the direction of the burst
(Schlegel et al. 1998).