[AAVSO-HEN] GRB 090817: 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:  9822
SUBJECT: GRB 090817: Swift/UVOT Upper Limits
DATE:    09/08/17 15:58:28 GMT
FROM:    Alice Breeveld at MSSL-UCL  <aab at mssl.ucl.ac.uk>

  A. Breeveld (MSSL/UCL) and W. Baumgartner (GSFC) report on behalf of  
the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 090817   
11008 s after the INTEGRAL trigger (Beckmann et al., GCN Circ. 9815).  
No new sources are found in the UVOT data at the position of the XRT  
source (P.A. Evans et al., GCN Circ. 9819). Preliminary 3-sigma upper  
limits using the UVOT photometric system (Poole et al. 2008, MNRAS,  
383, 627) and a 3 arcsec radius aperture, for the initial summed  
exposures are:

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

white         11516        17719          413         >21.3
v                11975        12398          416         >19.6
b                11058        17509          787         >21.2
u                11008        17157           78         >19.5

The values quoted above are not corrected for the Galactic extinction  
due to the reddening of E(B-V) = 0.66 in the direction of the burst  
(Schlegel et al. 1998).