[vsnet-grb-info 2378] GRB 051109a: MDM Observations

[GCN Circulars]

TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  4215
SUBJECT: GRB 051109a: MDM Observations
DATE:    05/11/09 03:52:12 GMT
FROM:    Jules Halpern at Columbia U.  <jules at astro.columbia.edu>

N. Mirabal (U. Michigan), J. P. Halpern, and S. Tonnesen (Columbia U.)
report on behalf of the MDM Observatory GRB follow-up team:

"We are observing the afterglow of Swift GRB 051109 detected by ROTSE-IIIb
(Rykoff et al. GCN #4211, Schaefer et al. GCN #4214) using the MDM 2.4m 
telescope and a Gunn r filter under partly cloudy conditions.  From 38 minutes
to 148 minutes after the burst, the OT faded from R = 18.21 +/- 0.05 to
R = 19.22 +/- 0.08.  Magnitudes are referenced to a USNO B1.0 star at 
22h01m14.60s +40d49'25.3" (J2000) having R=17.23.  This corresponds to a 
power-law decay index of -0.68.  Observations are continuing."