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GCN Circular 9907

GRB 090912 optical upper limit
2009-09-13T10:17:51Z (15 years ago)
AAVSO GRB Network at AAVSO <>
Arto Oksanen (Hankasalmi Obs., Hankasalmi, Finland) reports to the AAVSO 
International High Energy Network the following optical observations of 
the field of GRB090912 (GCN Circ. #9905, Ukwatta et al.):

A. Oksanen reports an upper limit on the optical afterglow of CR=21.6, 
measured relative to USNO-A2.0 1500-05568008 (R=15.7).  The X-ray 
afterglow position (Beardmore et al., GCN #9906) was observed using the 
0.4-m Hankasalmi Observatory RC telescope with an SBIG STL-1001E CCD 
camera and clear filter.  A total of 57 one-minute exposures were 
obtained, with the mid-point of the exposures at 2009 Sept 12 19:33 UT, 
approximately 3.7 hours post-burst.  Two faint stars near the burst 
location are present in DSS2 images, but there is no transient source at 
the burst location to a limit of CR=21.6.

A detailed report of these observations may be found at the following URL:

A fits image is also available at

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