[vsnet-grb-info 5195] GRB 071010B optical photometry

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  6892
SUBJECT: GRB 071010B optical photometry
DATE:    07/10/11 19:33:51 GMT
FROM:    AAVSO GRB Network at AAVSO  <matthewt at aavso.org>

A. Oksanen (Nyrola Observatory, Jyvaskyla, Finland), M. Templeton (AAVSO) 
and A. Henden (AAVSO) report further details on optical observations of 
GRB071010B (GCN #6871, Markwardt et al.; GCN #6873 Oksanen; GCN #6878 
Kennea et al.; GCN #6884 Kann et al.):

Further to the initial report given in GCN #6873, Arto Oksanen reports 
unfiltered photometry of the GRB 071010B afterglow spanning 2007 Oct 10 
21:02:33 UT to 2007 Oct 11 03:24:27 UT (T0 + 17 minutes to T0 + 6 hours 39 
minutes post-burst).  The data are reasonably well fit by a single power 
law with index -1.14.  The measured unfiltered magnitudes are 
approximately 0.3 magnitudes fainter than the Rc magnitudes reported by 
Kann et al (GCN #6884) taken at the same time, which is consistent with 
differences in zero-point calibration and bandpass.  It should be noted 
that this field is covered by the SDSS, and that the AAVSO will obtain a 
BVRI calibration with the Sonoita Research Observatory, weather 
permitting.

Oksanen also reports additional preliminary Ic and V-band magnitudes:

2007 Oct 10, 21:32 UT   Ic = 17.64 +/- 0.05
2007 Oct 10, 21:52 UT   V  = 18.30 +/- 0.05

Both magnitudes are calibrated relative to the transformed SDSS ugriz
magnitudes for the object at RA 10:01:54.62, Dec +45:40:29.0 (J2000).

Further details of these observations, light curves, and analyses are in
preparation for publication in the electronic Journal of the AAVSO.

Full details of the observations are available at the following URL:
ftp://ftp.aavso.org/grb/ArtoOksanen_GRB071010B_2454384.45422_.txt

The AAVSO thanks the Curry Foundation for their continued support of the
AAVSO International High Energy Network.