TITLE:   GCN CIRCULAR
NUMBER:  20097
SUBJECT: GRB 161022A: Swift/UVOT Upper Limits
DATE:    16/10/22 16:48:34 GMT
FROM:    Lea Hagen at PSU  <lea.zernow.hagen@gmail.com>

L. M. Z. Hagen (PSU) and M. Stamatikos (OSU/NASA/GSFC)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 161022A
137 s after the BAT trigger (Stamatikos et al., GCN Circ. 20087). No
optical afterglow consistent with the XRT position (Evans et al. GCN
Circ. 20094) 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 early exposures are:

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

white              137         1544          539         >21.25
u                  296         1668          333         >19.90
b                  551         1692           99         >19.27
v                  627         1421           97         >18.34
uvw1               676         1644          116         >18.86
uvm2               824         1272           38         >17.99
uvw2               602         1570          116         >19.10


The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.04 in the direction of the burst
(Schlegel et al. 1998).