GCN Circular 6929
Subject
GRB 071013: TNT optical data refined analysis
Event
Date
2007-10-17T15:08:04Z (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 and W.K. Zheng on behalf of EAFON report:
We refined the TNT data obtained in Oct. 13 (GCN 6908)
the object observed by Kornienko et al. (GCN 6925) can
not be confirmedin our R band images that were observed
in the same period.Our data was taken under bad seeing ~4".
In combined 6*60s R band image taken bewteen 12:39:03 -
12:47:54 (UT), we could not see the object at the position
RA(J2000)=18:37:49.1 Dec(J2000)=+33:50:25(Kornienko et al., GCN 6925).
The source of USNO-B1.0 1238-0299614(RA(J2000)=18:37:48.84
Dec(J2000)= +33:50:26.7) was marginally detected in this combined
image at 2.5 sigma level, and no obvious new object around was detected
at the same sigma level. We examined images before
and after this period, also no obvious new object was detected.
Using the same comparison star at RA (J2000) = 18:38:05.67,
Dec (J2000) = +33:54:14.61 which has R2=17.22 (Kann et al.,
GCN 6917, GCN 6926),we estimate the USNO-B1.0 1238-0299614 star
had the following magnitude at the epoch of our observation (GCN 6908):
---------------------------------------------------
T_start(UT) T_stop(UT) Band Exptime Mag M_err
12:21:38 12:38:45 R 13*60s 19.3 0.3
12:39:03 12:47:54 R 6*60s 19.4 0.4
12:48:47 13:46:44 R 11*300s 19.7 0.2
---------------------------------------------------
We suggest the object reported in GCN6926 is the same star.
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