TITLE:   GCN CIRCULAR
NUMBER:  9471
SUBJECT: Corrections to GRB 090531B Swift/UVOT Upper Limits
DATE:    09/06/01 14:29:44 GMT
FROM:    Patricia Schady at MSSL/Swift  <ps@mssl.ucl.ac.uk>

P. Schady (MSSL-UCL) and J. R. Cummings (NASA/UMBC) report on behalf of 
the Swift/UVOT team:

We report a mistake in a few of the times provided in GCN 9469, including 
the start time of the observations, which was in fact 3849 s after the BAT 
trigger (Cummings et al., GCN Circ. 9461). Also, the exposure times of the 
UVOT observations should have been two times the values given.

The corrected 3-sigma upper limits for the UVOT observations of the field 
of GRB 090531B are provided below.

Filter T_mid(s)  Exp(s)  3-sig Mag UL

white    3924      147      > 20.52
v        4105      197      > 19.08
b        4926      197      > 20.06
u        4721      197      > 19.74
uvw1     4515      197      > 19.65
uvm2     4310      197      > 19.32
uvw2     5336      197      > 19.61

The values quoted above are not corrected for the large Galactic 
extinction due to the reddening of E(B-V)=1.12 in the direction of the 
burst (Schlegel et al. 1998). The photometry is on the UVOT photometric 
system described in Poole et al. (2008, MNRAS, 383, 627).