GCN Circular 18032
Subject
GRB 150716A: Continued RATIR Optical Observations
Date
2015-07-17T18:44:52Z (9 years ago)
From
Alan M. Watson at Instituto de Astronomia UNAM <alan@astro.unam.mx>
Alan M. Watson (UNAM), Nat Butler (ASU), Alexander Kutyrev (GSFC), William
H. Lee (UNAM), Michael G. Richer (UNAM), Chris Klein (UCB), Ori Fox (UCB),
J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara
(ORAU/GSFC), Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico
Ramirez-Ruiz (UCSC), Jos� A. de Diego (UNAM), Leonid Georgiev (UNAM),
Jes�s Gonz�lez (UNAM), Carlos Rom�n-Z��iga (UNAM), Neil Gehrels (GSFC),
and Harvey Moseley (GSFC) report:
We observed the field of GRB 150716A (Kocevski et al., GCN 18027) with the
Reionization and Transients Infrared Camera (RATIR; www.ratir.org) on the
1.5m Harold Johnson Telescope at the Observatorio Astron�mico Nacional on
Sierra San Pedro M�rtir from 2015/07 17.16 to 2015/07 17.46 UTC (20.69 to
27.82 hours after the BAT trigger), obtaining a total of 4.31 hours
exposure in the r and i bands.
In these observations, the source reported by Watson et al. (GCN 18028) is
detected with
r 20.43 � 0.02
i 19.89 � 0.02
These magnitudes are in the AB system and are not corrected for Galactic
extinction in the direction of the GRB.
While these formal errors would suggest a slight fading compared to the
first night, in a crowded field such as this one, the real errors in the
photometry are likely to be much larger than these formal errors of 0.02
mag. We feel that there is no strong evidence for fading. Also, as noted
by Cenko & Perley (GCN 18029), this source is significantly outside the
enhanced XRT error region reported by Sbarufatti et al. (GCN 18030). We
therefore conclude that it is not the afterglow.
We see no evidence for the source reported by Cenko & Perley (GCN 18029)
in any of our images. However, this is not unexpected, since our images
have significantly worse image quality than theirs.
We thank the staff of the Observatorio Astron�mico Nacional in San Pedro
M�rtir.