[vsnet-grb-info 6733] GRB 081007, Faulkes Telescope North optical observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  8333
SUBJECT: GRB 081007, Faulkes Telescope North optical observations
DATE:    08/10/07 07:30:58 GMT
FROM:    James Smith at ARI,Liverpool John Moors U  <rjs at astro.livjm.ac.uk>

R.J. Smith, A. Melandri, I.A. Steele, D.F. Bersier, C.G. Mundell,
(Liverpool JMU), A. Gomboc (Ljubljana), C. Guidorzi (INAF-OAB)
on behalf of a larger collaboration reports:

The robotic 2m Faulkes Telescope North located in Hawaii observed
the field of the GRB 081007 (Baumgartner et al. GCN 8330) starting
automatically as soon as the target rose above the observable horizon
about 17 minutes after the GRB time.

A fading optical source is detected at the XRT position reported by
(Baumgartner et al. GCN 8330). Over the period from 0.2 - 1 hour after the
burst, the OT is seen to fade in both R and I with a flux power law slope
of -0.7.

Filter  Mag		T_mid[min]
-----------------------------
R       17.9 +/- 0.4	17.50
R       18.6 +/- 0.4	46.66

I       17.1 +/- 0.4	21.55
I       17.6 +/- 0.4	39.38
-----------------------------


The calibration was performed using the R2 and I magnitudes of the
USNOB-1 catalogue field star at 22:39:43 -40:10:15.3 J2000. A equivalent
amount of B-band data in which the source is detected have also been
obtained and are being analysed. Further observations are ongoing.