GCN Circular 10419
A. N. Morgan, B. E. Cobb, C. R. Klein, J. S. Bloom (UC Berkeley), report: We observed the field of GRB 100213B (Vetere et al., GCN 10412) with the 1.3m PAIRITEL located at Mt. Hopkins, Arizona. Observations began under good weather conditions at 2010-02-14 02:53:48 UT, ~3.92 hours after the Swift trigger. In mosaics (effective exposure time of ~2387 seconds) taken simultaneously in the J, H, and Ks filters, we do not detect any sources within the XRT error circle, nor at the potential NOT position (Malesani et al., GCN 10413). The preliminary photometry yields: post_burst t_mid(h) exp(s) filt U. Limit (3 sig) 4.44 2387 J > 19.2 4.44 2387 H > 18.2 4.44 2387 Ks > 17.1 Observations are ongoing. All magnitudes given in the Vega system, calibrated to 2MASS. No correction for Galactic extinction has been made to the above reported values.