GCN Circular 14830
D. A. Perley (Caltech) and S. B. Cenko (GSFC) report: The Palomar 60-inch telescope automatically responded to GRB 130609A (Cummings et al., GCN 14828) and began taking observations at 04:03:23 UT (58.25 minutes after the BAT trigger) as soon as the sky became dark. A sequence of cycled 60-second r, i, and z images was acquired. We detect no source consistent with the XRT localization in either individual images or in combined stacks of the first 6 images in each filter. Approximate 5-sigma limiting magnitudes from the combined images at an approximate mean time of 4:20 UT (75 minutes after the GRB trigger) are: r > 22.5 i > 21.5 z > 20.9 These limits are suggestive of a dark GRB. Cummings et al. report a detection of significant excess absorption in the XRT spectrum, which may indicate a dust-extinguished (as opposed to high-redshift) event, although given the quoted errors there the excess may be only marginal. NIR follow-up is highly encouraged.