[vsnet-grb-info 19111] GRB 170208B: Swift/UVOT Upper Limits

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  20657
SUBJECT: GRB 170208B: Swift/UVOT Upper Limits
DATE:    17/02/10 01:47:01 GMT
FROM:    Mike Siegel at PSU/Swift MOC  <siegel at swift.psu.edu>

M. H. Siegel (PSU) reports on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 170208B
127 s after the BAT trigger (Siegel et al., GCN Circ. 20632).
No optical afterglow consistent with the enhanced XRT position
(Goad et al. GCN Circ. 20635) or the GROND position
(Kruehler et al., GCN Circ. 20640)
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

u_FC               127          377          246         >20.7
v                  432         2146          214         >19.6
b                  382         2096          233         >20.3
u                  127         2211          598         >21.3
w1                 482         2195          214         >20.1
m2                 457         2171          214         >19.9
w2                 408         2122          234         >19.7

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.05 in the direction of the burst
(Schlegel et al. 1998).