GCN Circular 17200
Subject
GRB 141220A: Photometry from OSIRIS/GTC
Date
2014-12-20T11:08:46Z (9 years ago)
From
Antonio de Ugarte Postigo at IAA-CSIC <deugarte@iaa.es>
A. de Ugarte Postigo (IAA-CSIC, DARK/NBI), C.C. Thoene (IAA-CSIC),
J. Gorosabel (IAA-CSIC, UPV-EHU), N.R. Tanvir (U. Leicester),
J.P.U. Fynbo (DARK/NBI), P. Pesev (GRANTECAN), G. Gomez Velarde
(GRANTECAN), and D. Perez Valladares (GRANTECAN) report on behalf
of a larger collaboration:
Photometric observations of the afterglow of GRB 141220A (Cummings et al.
GCN 17196, Gorosabel et al. GCN 17197, de Ugarte Postigo et al. GCN 17198)
were obtained by OSIRIS/GTC starting 20.6 min after the GRB onset. The
afterglow was detected at r' = 18.11+/-0.05 mag in the first image and had
decayed by 0.6+/-0.1 mag 38.7 min after the burst. Using our photometric data
we derive a decay slope of alpha=0.96+/-0.11 (where F_nu ~ t^-alpha). These
results are consistent with the observations reported by Guidorzi et al. (GCN
17199). Our photometry was performed using SDSS stars as reference.
We encourage further observations and in particular spectroscopy of the
afterglow, in particular to check for possible variability of the FeII* features
between 5400 and 6100 A.