[vsnet-grb-info 16601] GRB 150527A: Swift/UVOT Upper Limits

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  17882
SUBJECT: GRB 150527A: Swift/UVOT Upper Limits
DATE:    15/05/27 21:46:10 GMT
FROM:    Alice Breeveld at MSSL-UCL  <a.breeveld at ucl.ac.uk>

A. A. Breeveld (UCL-MSSL) and P. A. Evans (U. Leicester)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 150527A 68 
s after the BAT trigger (Evans et al., GCN Circ. 17874).
No optical afterglow consistent with the enhanced XRT position (Evans et 
al. GCN Circ. 17879) or with the RATIR or REM sources (Butler et al., 
GCN Circ. 17876 and Nicastro et al., GCN Circ. 17881) is detected in the 
initial UVOT exposures.
Preliminary 3-sigma upper limits using the UVOT photometric system 
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first finding 
chart (FC) exposure and subsequent exposures are:

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

white_FC            68          218          147         >20.2
u_FC               280          523          240         >19.1
white            10385        11927         1542         >21.2
v                 4315         4515          197         >18.8
b                 3700        10380         1082         >20.8
u                  280         6271          623         >19.6
w1                5920         6120          197         >19.4
w2                4110        12019          281         >19.8

The magnitudes in the table are not corrected for the Galactic 
extinction due to the reddening of E(B-V) = 0.97 in the direction of the 
burst (Schlegel et al. 1998). We note however that the value for 
extinction could be unreliable at this position.