GCN Circular 11422

Chris Stockdale (Churchill, Victoria, Australia) reports to the AAVSO
International High Energy Network the following optical observation of
GRB 101024 (GCN #11370, De Pasquale et al.):

Chris Stockdale reports a detection of the optical afterglow of GRB 
101024 (GCN #11370, De Pasquale et al.; #11371, De Pasquale et al.;
#11373, Hentunen et al.; #11382, Laas-Bourez et al.; #11383 Kruehler et 
al.), detecting the afterglow at the same position as the Swift UVOT 
position. The afterglow was observed unfiltered for 24 minutes beginning 
at 12:42:07 UT on 2010 October 24.  Thirteen exposures of 24 minutes 
were taken for the detection; a median combination of images 2 through 
13 having a midpoint time of 12:54:25 UT on 2010 October 24 yields a CR 
magnitude of 19.3 with calculated S/N of 5.5; the magnitude was measured 
relative to the R-band catalog magnitude of USNO-B1.0 0127-0023867 
(R=15.7).  Observations were made using an SBIG ST-7XME CCD camera 
attached to a 280 mm Schmidt-Cassegrain.  The position of the afterglow 
was imaged for an additional 60 minutes subsequent to these frames, but 
the source was not detected.

The AAVSO High Energy Network was made possible through grants from the
Charles Curry Foundation and NASA.