TITLE:   GCN CIRCULAR
NUMBER:  16182
SUBJECT: GRB 140428A: 1.5m OSN I-band detection
DATE:    14/04/29 11:34:51 GMT
FROM:    Javier Gorosabel at IAA-CSIC  <jgu@iaa.es>

F.J. Aceituno (OSN/IAA-CSIC), A.J. Castro-Tirado (IAA-CSIC/UMA), R.
Sanchez-Ramirez (IAA-CSIC), J. Gorosabel (IAA-CSIC/UPV-EHU), report on
behalf of a larger collaboration:

“We observed the field of GRB 140428A (Kocevski et al., GCN 16177; Page 
et al., GCN 16178) with the 1.5m OSN telescope at Observatorio de Sierra
Nevada. Three 300s images were acquired in the I-band starting on Apr 29,
00:09:39 UT (i.e. ~1.5 hours burst). A preliminary reduction clearly shows
the optical afterglow reported by Perley (GCNC 16180) with a Vega
magnitude of I~20.8. This magnitude must be taken with caution given the
likely presence of the Lyman-alpha break in the I-band filter pass-band.”