[vsnet-grb-info 15272] GRB 140709A: 10.4m GTC optical decay

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  16564
SUBJECT: GRB 140709A: 10.4m GTC optical decay
DATE:    14/07/10 11:39:14 GMT
FROM:    Juan Carlos Tello at IAA-CSIC  <jtello at iaa.es>

A.J. Castro-Tirado (IAA-CSIC, ISA-UMA), J. Gorosabel (IAA-CSIC, UPV-EHU),
J. C. Tello, R. Cunniffe, A. Gonzalez-Rodriguez, A. Sota, M. Jelinek, S.
Jeong, O. Lara-Gil, S. R. Oates, R. Sanchez-Ramirez (IAA-CSIC, Granada), P.
Kubanek (IP-ASCR, Prague) and  S. Pandey (ARIES) report:

The field of GRB 140709A (Hagen et al. GCNC  16546) was observed in i'-band
with  the 10.4m GTC telescope in two epochs centered on July 9.12955 and
10.10966 UT (1.9 and 25.4 hours post burst). Comparison between those two
epochs reveals that the optical candidate reported by Castro-Tirado et al.
(GCNC 16554) has faded by ~0.7 mags (from i'~21.3 to 22.0, both in AB),
implying a shallow decay index of ~0.2.  A similar decay is measured in
z'-band.