2011ApJ...737...83L

We present deep 1.2 mm continuum mapping of a 566 arcmin² area within the Lockman Hole North (LHN) field, previously a target of the Spitzer Wide-Area Infrared Extragalactic survey and extremely deep 20 cm mapping with the Very Large Array, which we have obtained using the Max-Planck millimeter bolometer (MAMBO) array on the IRAM 30 m telescope. After filtering, our full map has an rms sensitivity ranging from 0.45 to 1.5 mJy/beam, with an average of 0.75 mJy/beam. Using the pixel flux distribution (PFD) in a map made from our best data, we determine the shape, normalization, and approximate flux density cutoff for 1.2 mm number counts well below our nominal sensitivity and confusion limits. After validating our full data set through comparison with this map, we successfully detect 41 1.2 mm sources with signal-to-noise ratio (S/N) > 4.0 and S_1.2 mm_≃ 2-5 mJy. We use the most significant of these detections to directly determine the integral number counts down to 1.8 mJy, which are consistent with the results of the PFD analysis. Ninety-three percent of our 41 individual detections have 20 cm counterparts, 49% have Spitzer/MIPS 24 µm counterparts, and one may have a significant Chandra X-ray counterpart. We resolve ≃ 3% of the cosmic infrared background (CIB) at 1.2 mm into significant detections and directly estimate a 0.05 mJy faint-end cutoff for the counts that is consistent with the full intensity of the 1.2 mm CIB. The median redshift of our 17 detections with spectroscopic or robust photometric redshifts is z_median= 2.3, and rises to z_median= 2.9 when we include redshifts estimated from the radio/far-infrared spectral index. By using a nearest neighbor and angular correlation function analysis, we find evidence that our S/N > 4.0 detections are clustered at the 95% confidence level.