[vsnet-grb-info 26510] SGR 1830-0645: Swift/UVOT Upper Limits

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  28610
SUBJECT: SGR 1830-0645: Swift/UVOT Upper Limits
DATE:    20/10/13 14:20:18 GMT
FROM:    Paul Kuin at MSSL  <npkuin at gmail.com>

Paul Kuin (UCL-MSSL) and Kim Page (U.Leicester)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of SGR 1830-0645/
GRB 201010 71 s after the BAT trigger (Page et al., GCN Circ. 28594).
This field is crowded with sources. Near the XRT position
(Osborne et al. GCN Circ. 28596) we find two sources which were
both observed not to vary within our measuring accuracy of 0.07 mag.
Hence, no optical afterglow consistent with the XRT position
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            71          221          147         >17.6
u_FC               284          534          246         >18.1
white               71          757          186         >17.6
v                  614         5462          216         >16.4
b                  540          733           39         >17.6
u                  284         6049          434         >18.0
w1                 664         5872          216         >18.6
m2                 639         5667          216         >19.7
w2                 590         5257          216         >19.3

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 1.78 in the direction of the burst
(Schlegel et al. 1998).