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GCN Circular 15362

Subject
GRB 131018B: Swift/UVOT Upper Limits
Date
2013-10-20T21:17:55Z (11 years ago)
From
Samantha Oates at MSSL <sro@mssl.ucl.ac.uk>
S. R. Oates (MSSL-UCL) and P. D'Avanzo (INAF-OAB)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 131018B
83 ks after the LAT trigger (Vianello et al., GCN Circ. 15357).
No new optical candidate is detected within the LAT 
error circle (Vianello et al., GCN Circ. 15357) in the initial UVOT exposures.
We note an optical source within the error circle of the 
candidate XRT position (D'Avanzo et al., GCN Circ. 15361), 
which is found in the USNO-B1 catalogue.

Preliminary 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the initial exposures are:

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

white          90363	    91160          785         >21.7
v              91168	    91427          255         >19.4
u              88969	    95244         1300         >20.6

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.58 in the direction of the burst
(Schlegel et al. 1998).
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