TITLE:   GCN CIRCULAR
NUMBER:  12760
SUBJECT: GRB 111228A: PAIRITEL NIR Detection
DATE:    11/12/29 08:18:18 GMT
FROM:    Adam Morgan at U.C. Berkeley  <qmorgan@gmail.com>

GRB 111228A: PAIRITEL NIR Detection

A. N. Morgan (UC Berkeley) reports:

We observed the field of GRB 111228A (Ukwatta et al., GCN 12737) with
the 1.3m PAIRITEL located at Mt. Hopkins, Arizona. Observations began
at 2011-12-29 06:55:25 UT, ~15.2 hours after the Swift Trigger.  In
mosaics (effective exposure time of 0.46 hours) taken simultaneously
in the J, H, and Ks filters, we marginally detect a source at the
optical afterglow location (Ukwatta et al., GCN 12737; Xin et al., GCN
12738; Klotz et al., GCN 12742; Pandey et al., GCN 12745; Nascimbeni
et al., GCN 12748; Xu et al. GCN 12750; Nysewander et al., GCN 12751;
Kuin & Ukwatta, GCN 12752; Gorosabel et al., GCN 12753; Hentunen et
al., GCN 12754; Sinykov et al., GCN 12756; Guelbenzu et al., GCN
12757).

The preliminary photometry yields:

post burst
t_mid (hr) exp.(hr) filt  mag    m_err
15.56      0.46     J     18.3   0.2
15.56      0.46     H     17.8   0.3
15.56      0.46     Ks    16.2   0.3

All magnitudes are given in the Vega system, calibrated to 2MASS. No
correction for Galactic extinction has been made to the above reported
values. Further observations are ongoing.