[vsnet-grb-info 8228] GRB 090809: afterglow confirmation at the NOT

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  9755
SUBJECT: GRB 090809: afterglow confirmation at the NOT
DATE:    09/08/10 00:27:57 GMT
FROM:    Dong Xu at DARK,NBI  <dong at astro.ku.dk>

D. Xu, G. Leloudas, D. Malesani, J.P.U. Fynbo (DARK/NBI), P. Jakobsson 
(Univ. of Iceland), and G. Furesz (CfA/Harvard) report on a larger 
collaboration:

We observed the field of GRB 090809 (Markwardt et al., GCN 9754) with 
the Nordic Optical Telescope equipped with ALFOSC. We obtained 3x300 s 
I-band frames, starting on August 9th, 21:49:10 UT, 4.29889 hr after the 
burst; and 1x300 s R-band frame,  starting 5.29861 hr after the burst.

We confirm the presence of the UVOT source (Markwardt et al., GCN 9754) 
at coordinates:

RA(J2000) = 21:54:43.17
Dec(J2000) = -00:05:01.9

which are consistent with the UVOT position. We note that the source is 
not visible in the archival SDSS frames of this field, thereby proving 
that it is the optical afterglow of GRB 090809.

The afterglow is detected in each I-band and R-band frame. The 
preliminary magnitudes are I~19.9 and R~20.3 respectively, against the 
same reference star, 0899-0602834 in the USNO B1 catalog.

Further photometric observations are underway. We encourage 
spectroscopic follow-up.