GCN Circular 13805
Subject
GRB 120923A: Swift/UVOT Upper Limit
Date
2012-09-23T12:50:40Z (12 years ago)
From
Alice Breeveld at MSSL-UCL <aab@mssl.ucl.ac.uk>
A. A. Breeveld (MSSL-UCL), V. N. Yershov (MSSL-UCL) and N. P. M. Kuin
(MSSL-UCL) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 120923A
143 s after the BAT trigger (Yershov et al., GCN Circ. 13796).
No optical afterglow consistent with the XRT or Gemini position (Goad et
al., GCN Circ. 13801, Levan et al., GCN Circ. 13802) is detected in the
initial UVOT exposure.
A preliminary 3-sigma upper limit using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first finding
chart exposure is:
Filter T_start(s) T_stop(s) Exp(s) Mag
white 143 293 147 >21.3
The magnitude in the table is not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.16 in the direction of the burst
(Schlegel et al. 1998).