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GCN Circular 5623

GRB 060926: OPTIMA-Burst -- further observations
2006-09-27T00:40:02Z (17 years ago)
Alexander Stefanescu at MPE <>
A. Stefanescu, F. Schrey, S. Duscha, G. Kanbach, M. Muehlegger, N.
Primak, H. Steinle (MPE Garching) of the OPTIMA-Burst Team report the

We have observed the OT of GRB 060926 under unfavorable weather 
conditions until it became unobservable at ~18:40 UT. To make 
comparision easier with GCN 5618 (U. Kiziloglu et al.), we have 
callibrated our observations against the R2-magnitudes of 4 nearby 
USNO-B1 stars (1030-0324059, 1030-0324042, 1030-0324039, 1030-0324046). 
We estimate the magnitude of the OT as follows:

    t-t_BAT        exp-time
[min] (mid-exp)     [s]         R_mag
    35.4             600         20.3 +-0.5
    59.7             600         20.6 +-0.5
    72.7             600         20.7 +-0.7
    90.7             2x 1200     21.0 +-0.7
    101.2            1200        21.1 +-0.7

We fitted these values with a powerlaw with a decay index of 0.73 +-0.1.
This is significantly shallower than the powerlaw between the MASTER 
observations (GCN 5619, V. Lipunov et al.) and ours, with a decay index 
of 0.90 +-0.06 - allthough this could be due to incompatibilities in 

We thank J. Papamastorakis of the University of Crete and his team for 
the possibility to use the 1.3m Telescope at Skinakas Observatory for a 
prolonged period of time.
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