[vsnet-grb-info 21473] GRB 181225A: KAIT Follow-Up Observations with Upper Limit

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  23572
SUBJECT: GRB 181225A: KAIT Follow-Up Observations with Upper Limit
DATE:    18/12/28 04:44:24 GMT
FROM:    Weikang Zheng at UC Berkeley  <weikang at berkeley.edu>

WeiKang Zheng, Keto Zhang, Alexei V. Filippenko, and Sergiy Vasylyev
(UC Berkeley) report on behalf of the KAIT GRB team:

The 0.76-m Katzman Automatic Imaging Telescope (KAIT), located at
Lick Observatory, observed the field of the AGILE-, GBM- and
LAT-detected burst GRB 181225A (Ursi et al., GCN Circ. 23560;
Arimoto et al. GCN Circ., 23561; Poolakkil et al., GCN Circ. 23562).
More than 250 galaxies near the Fermi/LAT localization (Arimoto et al.
GCN Circ., 23561) were selected from the Glade catalog
(http://aquarius.elte.hu/glade/) according to
their priority score. On 2018 Dec. 26 UT, KAIT observed 82 of them having
top-priority scores, with each clear-filter exposure time being 60 s.
The first image was taken at 01:47:23 UT, about 14.05 hr after
AGILE/MCAL trigger time, and the last image at 04:24:11 UT.

For the two Swfit/XRT sources reported by D'Elia (GCN 23565), the first
one was not covered by KAIT images. The second source, which was considered
to be a candidate X-ray afterglow for GRB181225A, was covered by one
of the KAIT image taken at 03:46:38 UT (namely 16.04 hours after
AGILE/MCAL trigger. However, we do not detect any optical afterglow
candidate
around the second XRT source, with limiting mag ~19.0 calibrated to the
Pan-STARRS1 catalog.