[vsnet-grb-info 15821] GRB 141121A: RATIR Optical and NIR Observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  17109
SUBJECT: GRB 141121A: RATIR Optical and NIR Observations
DATE:    14/11/28 16:04:21 GMT
FROM:    Alan M. Watson at Instituto de Astronomia UNAM  <alan at astro.unam.mx>

Nat Butler (ASU), Alan M. Watson (UNAM), 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), José
A. de Diego (UNAM), Leonid Georgiev (UNAM), Jesús González (UNAM), Carlos
Román-Zúñiga (UNAM), Neil Gehrels (GSFC), and Harvey Moseley (GSFC) report:

We observed the field of GRB 141121A (Lien et al., GCN 17075) with the
Reionization and Transients Infrared Camera (RATIR; www.ratir.org) on the 1.5m
Harold Johnson Telescope at the Observatorio Astronómico Nacional on Sierra San
Pedro Mártir from 2014/11 28.29 to 2014/11 28.54 UTC (171.20 to 177.06 hours
after the BAT trigger), obtaining a total of 4.62 hours exposure in the r, i,
and z bands.

For a source within the Swift-XRT error circle, in comparison with the SDSS DR9,
we obtain the following detections and upper limits (3-sigma):

r = 21.87 +/- 0.05
i = 21.62 +/- 0.05
z > 21.03

These magnitudes are in the AB system and are not corrected for Galactic
extinction in the direction of the GRB.

Compared to our previous observations (Butler et al., GCN 17101; Watson et al.,
GCN 17105), the afterglow continues to fade roughly as t^-1.7.

We thank the staff of the Observatorio Astronómico Nacional in San Pedro Mártir.