Columbia University Astronomy and 

University of Michigan 

MDM Observatory GRB Team

1.3m Followup
R.A. 04h 17m 09s.4, Decl. +18o11' 57."9 (J2000.0)

GCN Circular #3900: GRB 050827: Optical Limit
J. P. Halpern (Columbia U.) reports on behalf of the MDM Observatory
GRB follow-up team:

"I observed the error box of GRB 050827 (Swift trigger #152325, GCN #3893)
in the R band with the MDM 1.3m telescope for 50 minutes starting on
Aug. 28 09:32 UT, or 14.6 hours after the burst.  There is no optical
object to a limiting magnitude R=23.5 within 16", or twice the error circle 
radius, of the XRT candidate afterglow reported by Capalbi et al. (GCN #3899).  
Even after correcting this limit for Galactic absorption A(R)=1.47 mag at its
location (Schlegel et al. 1998), it would be unusual for a persistent X-ray 
source of flux 1.0E-12 erg cm^-2 s^-1 to have no optical counterpart.  So
this supports the identification of the X-ray source as the GRB afterglow."

Jules Halpern
Nestor Mirabal
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Last Modified: August 30, 2005