[vsnet-grb-info 16278] GRB 150309A: Swift/UVOT Upper Limits

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  17559
SUBJECT: GRB 150309A: Swift/UVOT Upper Limits
DATE:    15/03/10 13:16:03 GMT
FROM:    Samantha Oates at MSSL  <sro at mssl.ucl.ac.uk>

S. R. Oates (IAA-CSIC/UCL-MSSL) and J. R. Cummings (NASA/UMBC)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 150309A
140 s after the BAT trigger (Cummings et al., GCN Circ. 17553).
No optical afterglow consistent with the XRT position
(Osborne et al. GCN Circ. 17555)
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           140          290          147         >20.3
u_FC               299          549          246         >19.4
white              140        12463          881         >21.1
v                  630         6293          432         >19.3
b                  555        12046         1121         >20.8
u                  299        17720         2241         >21.1
w1                 679        16806         1318         >20.8
m2                 654         6498          432         >20.1
w2                 605         6089          432         >20.3

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.14 in the direction of the burst
(Schlegel et al. 1998).