[vsnet-grb-info 10525] GRB 110420B: Swift/UVOT Upper Limits

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  11955
SUBJECT: GRB 110420B: Swift/UVOT Upper Limits
DATE:    11/04/21 14:29:56 GMT
FROM:    Samantha Oates at MSSL  <sro at mssl.ucl.ac.uk>

S. R. Oates (MSSL-UCL) & B. Sbarufatti (INAF-OAB/IASFPA) report on behalf of the Swift-UVOT team

The Swift/UVOT began settled observations of the field of GRB 110420B
2562 s after the BAT trigger (Sbarufatti et al., GCN Circ. 11944).
No optical afterglow is found within the BAT error circle.

Preliminary 3-sigma upper limits using the UVOT photometric system
(Poole et al. 2008, MNRAS, 383, 627) for the first finding chart (FC)
exposure and subsequent exposures are:

Filter         T_start(s)   T_stop(s)      Exp(s)         Mag
###############################################################
white_FC          2562         2711          147         >20.6
white             2562         4765          540         >20.5
v                 3541        16124         1322         >19.9
b                 2926        22368          621         >20.4
u                 2720        28151         1730         >20.0
w1                3950        28007         2844         >19.6
m2                3745        27103         2416         >19.5
w2                3336        15211         1279         >19.7
###############################################################

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).