GCN Circular 6965
Subject
GRB071018: 2nd epoch obsevations of Xinglong TNT
Event
Date
2007-10-21T18:24:51Z (18 years ago)
From
L.P. Xin at NAOC <xlp@bao.ac.cn>
L.P. Xin, M. Zhai, Y.L. Qiu, J.Y. Wei, J.Y. Hu, J.S. Deng,
J. Wang, Y. Urata and W.K. Zheng on behalf of EAFON report:
We observed the field of GRB071018 (Krim et al. GCN 6932) with the TNT 0.8m
telescope at Xinglong Observatory for the 2nd epoch, Observation was started
from 19:12:25 UT, 19th Oct. 1.494 days after the burst. A series of R-band
images were obtained. In our 14*600s combined images we can still find the
two sources of our last observation (Xin et al. GCN 6936).
The estimated bringhtness of the source #1 and #2 (Xin et al. GCN6936)
derieved from USNO-B1.0 R2 magnitude were R=20.67+-0.318 and R=20.72+-0.36
respectively. The magnitude of source #1 was consistent with the value
reported by SARA (Updike et al. GCN 6944) and Mercator (Alberto
Castro-Tirado, GCN6947). but bringter than the value of our last observation
(Xin et al. GCN6936), So the source #1 only maybe a avariable source as
reported (Adria, GCN 6944), and the source $2 also might not be the OT of the
burst.
At the locations of the XRT error circles of source 1 and source 2 (GCN 6943,
Beardmore et al.), We found no new optical source to the 3sigma limit
magnitude R=21.2 .
We also checked the combined image (Xin et al. GCN6936) obtained on 18th Oct,
No new source was found at the location of XRT source 2 to 3-sigma limit
magnitude R=21.5. The location of XRT source 1 was outside the field of view
of the combined image.
This massage may be cited.