[AAVSO-HEN] GRB 090813: Liverpool Telescope afterglow confirmation

[grb at aavso.org]

The following is a GCN Circular circulated via the AAVSO network.
For an archive and more information on circulars visit:
http://lheawww.gsfc.nasa.gov/docs/gamcosray/legr/bacodine/gcn3_archive.html

TITLE:   GCN CIRCULAR
NUMBER:  9784
SUBJECT: GRB 090813: Liverpool Telescope afterglow confirmation
DATE:    09/08/13 06:17:10 GMT
FROM:    James Smith at ARI,Liverpool John Moors U  <rjs at astro.livjm.ac.uk>

R.J. Smith, I.A. Steele, Z. Cano (Liverpool JMU), C. Guidorzi (U.
Ferrara),  C.G. Mundell, A. Melandri, S. Kobayashi, C.J. Mottram,
D.F. Bersier,  (Liverpool JMU), A. Gomboc (U. Ljubljana), report on behalf 
of a large collaboration:

On 2009 August 13 at 04:13:40.8 UT the 2-m Liverpool Telescope
automatically began observing the Swift GRB 090813 (Cummings et al.,
GCN Circ. 9781) using the r' and i' filters. We confirm the detection by 
Gorosabel et al (GCN 9782) and Cenko et al (GCN 9783) of an optical 
counterpart to the XRT source. We measure a position of 15:03:05.9 
88:34:05.5 J2000 with an uncertainty of 1arcsec and further, confirm the 
OT is fading. Ths position is 1 arcsec from and therefore conssitent from 
that reported by Cenko et al (GCN 9783).


Mid Time     Delay from BAT   Total Exp  Filter     Mag
(UT)	     trigger (min)      (s)
----------------------------------------------------------
04:13:45.8      3.05		10	R	19.36 +/- 0.13
04:18:11.9      7.48		120	R	19.90 +/- 0.05
04:20:58.2     10.25		120	I	18.11 +/- 0.02
----------------------------------------------------------

Both astrometry and photometry is calibrated and quoted with respect
to USNO-B.

Further observations are ongoing.