[vsnet-grb-info 19798] GRB 170906C: Swift/UVOT Upper Limits

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  21835
SUBJECT: GRB 170906C: Swift/UVOT Upper Limits
DATE:    17/09/06 16:50:16 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 170906C
1296 s after the BAT trigger (Siegel et al., GCN Circ. 21826).
No optical afterglow consistent with the XRT position
(Evans et al. GCN Circ. 21828)
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          1296         1446          147         >21.6
white             1296         2585          284         >21.4
v                 1578         2635          136         >19.4
b                 1504         2913          333         >19.9
u                 1479         2708          156         >20.6
w1                1454         2684          156         >19.9
m2                2467         2487           19         >17.8
w2                2591         2611           19         >19.0

The magnitudes in the table 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).