GCN Circular 8699
Subject
GRB 081222: Faulkes Telescope South observations
Date
2008-12-22T13:51:17Z (15 years ago)
From
Cristiano Guidorzi at Ferrara U,Italy <guidorzi@fe.infn.it>
A. Melandri (Liverpool JMU), C. Guidorzi (U. Ferrara), D. Carter
(Liverpool JMU)
report on behalf of a larger collaboration:
On 2008 December 22 (10:17:46 UT) we began observing the field of GRB 081222
(Grupe et al. GCN Circ. 8691) with the Faulkes Telescope South.
Observations consisted of two sequences of 6x300s exposures acquired
using the SDSS-i and SDSS-r filters, respectively.
We clearly detect the optical afterglow reported by REM (Covino et al.
GCN Circ. 8692) and GROND (Updike et al. GCN Circ. 8693), with the following
magnitudes:
Telescope Filter T_mid[hr] Exposure[s] Mag
--------------------------------------------------------------
FTS SDSS-i 5.47 2x300 20.45 +/- 0.25
FTS SDSS-r 6.01 2x300 21.34 +/- 0.30
--------------------------------------------------------------
The calibration was performed using the R2 and I magnitudes of several
USNOB-1 catalogue field objects. Uncertainties include the different
zero points of the USNOB-1 stars. Compared with the value reported by GROND
(Updike et al. GCN Circ. 8693), we estimate a power-law index between the
two epochs of about 1.1 .