Columbia University Astronomy and 

University of Michigan 
Dartmouth College 
Astronomy and Physics

MDM Observatory GRB Team

GRB 050824: Optical follow-up
1.3m First 1.3m Last
2.4m (John T.) 2.4m (David R.)
00h48m56s.16, +22°36'33."0 (J2000.0)

GCN Circular #3907: GRB 050824: MDM Observations
J. P. Halpern (Columbia U.) and N. Mirabal (U. Michigan) report on behalf of
the MDM Observatory GRB follow-up team:

"We observed the Swift GRB 050824 afterglow (Gorosabel et al., GCN #3865)
in the R band on five consecutive nights using the MDM 1.3m telescope.
Photometry was established using two Landolt standard-star fields on one
photometric night.  From 5.6 to 12.6 hours, the decay is consistent with
a power law of index -0.55+/-0.05, which extrapolates well to the MASTER 
photometry at 24 and 47 minutes (Lipunov et al., GCN #3883).  This decay
index is similar to that seen in the Swift XRT light curve, -0.4+/-0.2
(Campana et al., CGN #3877), immediately preceding the MDM observations.
An unobserved inflection in the optical light curve then occurs, and from
1.3 to 4.4 days the decay index is -0.43+/-0.04.  Our final measured point
is R=22.18+/-0.06 on Aug. 29.32.

Images and light curves are posted at

This message may be cited."

Decay Curve
Expanded Decay Curve

Jules Halpern
Nestor Mirabal
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Last Modified: September 29, 2005