GCN Circular 3171
Subject
GRB050401: TNG R-band observation
Date
2005-04-02T11:36:52Z (20 years ago)
From
Nicola Masetti at IASF,CNR,Bologna <masetti@bo.iasf.cnr.it>
P. D'Avanzo, D. Fugazza (INAF-OAB), N. Masetti (INAF-IASF, Bologna) and
M. Pedani (TNG), on behalf of a larger collaboration, report:
"We have obtained R-band photometry of the optical afterglow (McNaught &
Price, GCN #3163; Rykoff et al., GCN #3165) of GRB050401 (Angelini et al.,
GCN #3161; Barbier et al., GCN #3162) using DOLoRes at TNG.
The observations, for a total exposure time of 30 minutes, were performed
under moderate seeing conditions (around 1.2 arcsec).
A preliminary analysis of the images allowed us to derive the following
photometry for the OT, calibrated after observing the SA104 Landolt
standard field:
R = 23.18 +/- 0.10 on 2005 April 2.072 UT, 11.39 hours after the burst
Using this OT magnitude and those reported in GCNs #3163 and #3165, and
assuming a canonical power-law decay, we obtain for the OT a decay index
alpha ~ 1, quite typical of GRB optical afterglows.
We are particularly grateful to the TNG staff for their remarkable support
to these observations."
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