GCN Circular 8764
Subject
GRB 090102: TAROT Calern observatory optical light curve
Date
2009-01-02T05:14:46Z (16 years ago)
From
Alain Klotz at CESR-CNRS <Alain.Klotz@free.fr>
Klotz, A. (CESR-OMP), Gendre, B. (OAMP),
Boer M. (OHP), Atteia J.L. (LATT-OMP) report:
We analyzed images of GRB 090102 detected by SWIFT
(trigger 338895) with the TAROT at the Calern
observatory, France.
In our previous GCN Circ. (9761) we made a mistake
in the celestial coordinates of the optical afterglow.
TAROT position is compatible with UVOT (Mangano et
al. GCNC 8762).
The first image is trailed with a duration of 60.0s
(see the description in Klotz et al., 2006, A&A 451, L39)
and we detect the growth of the optical light curve
that culminates at t0+60s (+/- 3s) with a brightness R=13.4
(i.e. ~40s after the end of the gamma activity).
We calibrated magnitudes in R band using
NOMAD1 1231-0209716 (R=13.31).
After t0+60s, the decay of the afteglow is classic with
a decay of alpha=1.6 +/- 0.2. Hereafter, TAROT Calern
data (tstart and tend are expressed in seconds after
the BAT trigger t0):
tstart tend R dR
40.8 46.8 14.3 0.2
46.8 52.8 13.6 0.1
52.8 58.8 13.4 0.1
58.8 64.8 13.4 0.1
64.8 70.8 13.5 0.1
70.8 76.8 13.7 0.1
76.8 82.8 13.7 0.1
82.8 88.8 14.0 0.1
88.8 94.8 14.1 0.1
94.8 100.8 14.3 0.1
107.6 137.6 14.4 0.2
144.6 174.6 14.9 0.2
181.6 211.6 15.5 0.3
Further observations are in progress