TITLE:   GCN CIRCULAR
NUMBER:  17632
SUBJECT: GRB 150323C: RATIR Optical Afterglow Observations
DATE:    15/03/24 06:49:44 GMT
FROM:    Owen Littlejohns at Az State U  <olittlej@asu.edu>

Alan M. Watson (UNAM), Owen Littlejohns (ASU), 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), 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 150323C (Amaral-Rogers, et al., GCN
17621) 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 2015/03 24.14 to 2015/03 24.27 UTC (10.20 to 13.42 hours
after the BAT trigger), obtaining a total of 2.49 hours exposure
in the r, i and z bands.

For a source within the Swift-XRT error circle (D'Elia, et al.,
GCN 17630), in comparison with the SDSS DR9, we obtain the
following detections and upper limit (3-sigma):

  r     23.00 +/- 0.15
  i     22.63 +/- 0.11
  z     > 20.61

These magnitudes are in the AB system and are not corrected for
Galactic extinction in the direction of the GRB. In comparison to
an earlier epoch of observations (Xin, et al., GCN 17631) we find
this magnitude to be consistent with a power-law decay with an
approximate temporal decay index alpha = 0.5.

We thank the staff of the Observatorio Astron�mico Nacional in
San Pedro M�rtir.