[vsnet-grb-info 4481] GRB 070406: Optical candidate

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  6253
SUBJECT: GRB 070406: Optical candidate
DATE:    07/04/07 15:04:31 GMT
FROM:    W.K. Zheng at NAOC  <zwk at bao.ac.cn>

L.P. Xin, M.Zhai, Y.L. Qiu, J.Y. Wei, J.Y. Hu, J.S. Deng,
and W.K. Zheng on behalf of EAFON report:

We have refined the first epoach of Xinglong TNT 80cm data of 
GRB070406(Cummings et al.; GCN 6247), we find an uncatalog object
at the location: RA, DEC  198.9206, +16.5708 (J2000),which is
RA (J2000) 13:15:41
Dec(J2000) +16:34:15
this position is 3.3 arcmin away from the center of BAT position but
3.3 arcmin is 0.3 arcmin far away from the uncertainty of BAT position.

We also reimaged this fied 35.4 hours after the burst with the same
band, preliminary result shows the object has faded ~1 mag during our
two epoach observation, the object has a mag of ~18.4 derived form
USNO-A2.0 35.4 hours after the burst. so we recommend this object as
the candidate of GRB070406 though it is 0.3 arcmin far away from the
uncertainty of BAT position.

We also find there is a faint galaxy 9.8 arcsec away from the candidate
in the SDSS image, at the location:RA, DEC 198.9192, +16.5732,
this galexy has a magnitude of r=22.07. While the galaxy mentioned in
GCN6249(Ofek et al.) lies on the other side of the BAT center positon.

We encourage further photometry and spectrum observation to confirm
this candidate.

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