[vsnet-grb-info 9052] SGR 1833-0832: Swift/UVOT Upper Limits

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  10540
SUBJECT: SGR 1833-0832: Swift/UVOT Upper Limits
DATE:    10/03/22 22:08:21 GMT
FROM:    Frank Marshall at GSFC  <marshall at milkyway.gsfc.nasa.gov>

F.E. Marshall (NASA/GSFC) and J.M. Gelbord (PSU)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of SGR 1833-0832
71 s after the BAT trigger (Gelbord et al., GCN Circ. 10526).
No optical afterglow consistent with the XRT position
(Evans and Goad, GCN_Circ. 10529) is detected in the initial UVOT exposures.
Preliminary 3-sigma upper limits using the UVOT photometric system
(Poole et al. 2008, MNRAS, 383, 627) for the first finding chart (FC)
exposures and subsequent exposures are:

Filter         T_start(s)   T_stop(s)      Exp(s)         Mag

white_FC            71          220          147         >20.6
u_FC               283          533          246         >20.5
white               71        57748         1793         >22.3
v                  612        69706         3549         >21.4
b                  539        57397         3660         >21.3
u                  283        75812         5479         >22.3
w1                4479        75666         6430         >21.8
m2                5710        74760         4446         >22.5
w2                5300        68903         3050         >22.3

The values quoted above are not corrected for the Galactic extinction
due to the very large reddening in the direction of the source
(Schlegel et al. 1998). The large X-ray column density to the source found 
with the Swift/XRT (Gelbord and Vetere, GCN Circ. 10531) also
indicates very large optical extinction.