[AAVSO-HEN] GRB 090813: P60 Optical Afterglow Confirmation

[grb at aavso.org]

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TITLE:   GCN CIRCULAR
NUMBER:  9783
SUBJECT: GRB 090813: P60 Optical Afterglow Confirmation
DATE:    09/08/13 05:25:55 GMT
FROM:    S. Bradley Cenko at Caltech  <cenko at srl.caltech.edu>

S. B. Cenko (Caltech) reports on behalf of a larger collaboration:

We have imaged the field of GRB090813 (Cummings et al., GCN 9781) with the
automated Palomar 60 inch telescope.  Observations were taken in the Sloan
r', i', and z' filters beginning at approximately 4:12 UT (~ 2 minutes
after the burst).

Inside the XRT error circle we find a fading point source with coordinates
(J2000.0):

   RA: 15:03:08.48
   Dec: +88:34:05.5

with an estimated error of ~ 0.3" in each coordinate.  Presumably this is
the same source identified by Gorosabel et al. (GCN 9782).

With reference to several USNO-B1 sources in the field, we measure the
following I-band magnitudes for the afterglow:

UT (mid-point)     Exposure (s)       Magnitude
----------------------------------------------------------------
04:15:47           60                 17.8
04:20:33           60                 18.2

Further observations are planned.