TITLE:   GCN CIRCULAR
NUMBER:  9006
SUBJECT: Further Swift/UVOT observations of GRB 090313
DATE:    09/03/16 20:55:05 GMT
FROM:    Patricia Schady at MSSL/Swift  <ps@mssl.ucl.ac.uk>

P.Schady (MSSL-UCL), F.E.Marshall (NASA/GSFC) and J. Mao (INAF-OAB) report 
on behalf of the Swift/UVOT team:

Following on from GCN 8990 (Schady et al.), we report on Swift/UVOT 
observations of GRB 090313 for all optical and ultraviolet filters. A 
fading source is detected in the v filter and marginally in the b-band 
filter at a position consistent with the optical afterglow reported by 
Chornock et al. (GCN 8979). These observations are in agreement with the 
spectroscopic redshift z=3.375 (Chornock et al., GCN 8994).

The magnitudes and 3-sigma upper limits for GRB 090313 within each 
co-added UVOT filter are as follows:

Filter   T_mid (hrs)    Exp (s)   Mag/3-sigma UL
v          11.0          551      20.10 +/- 0.30 (3.6 sigma)
b          11.2          770      21.50 +/- 0.38 (2.8 sigma)
u          8.1           1024     > 21.44
uvw1       8.6           1771     > 21.78
uvm2       9.3           886      > 21.22
uvw2       10.9          886      > 21.58

where T_mid is the weighted mean time of the observations. The values 
quoted above are not corrected for the Galactic extinction due to the 
reddening of E(B-V)  = 0.03 in the direction of the burst (Schlegel et al. 
1998). All photometry is on the UVOT photometry system described in Poole 
et al. (2008, MNRAS, 383, 627).

In addition, we note an error in GCN 8990 (Schady et al.), where we 
mistakenly labelled the results for the u filter as b and vice versa.