TITLE:   GCN CIRCULAR
NUMBER:  11861
SUBJECT: GRB 110402A: PAIRITEL NIR Upper Limits
DATE:    11/04/02 06:02:36 GMT
FROM:    Adam Morgan at U.C. Berkeley  <qmorgan@gmail.com>

A. N. Morgan, C. R. Klein, and J. S. Bloom (UC Berkeley) report:

We observed the field of GRB 110402A (Ukwatta et al., GCN 11857) with
the 1.3m PAIRITEL located at Mt. Hopkins, Arizona. Observations began
at 2011-04-02 04:28:41 UT, ~4.26 hours after the Swift Trigger.  In
mosaics (effective exposure time of 0.63 hours) taken simultaneously
in the J and H filters, we do not detect any source at the optical
afterglow location (Mundell et al., GCN 11858, Leloudas et al., GCN
11859).  Our preliminary Ks band reduction is corrupted.

The preliminary photometry yields:

post burst
t_mid (hr) exp.(hr) filt  U. Limit (3 sig)
4.77       0.63     J     > 19.1
4.77       0.63     H     > 18.2

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