THE BOLOCAM GALACTIC PLANE SURVEY: SURVEY DESCRIPTION AND DATA REDUCTION

Abstract

We present the Bolocam Galactic Plane Survey (BGPS), a 1.1 mm continuum\nsurvey at 33" effective resolution of 170 square degrees of the Galactic Plane\nvisible from the northern hemisphere. The survey is contiguous over the range\n-10.5 < l < 90.5, |b| < 0.5 and encompasses 133 square degrees, including some\nextended regions |b| < 1.5. In addition to the contiguous region, four targeted\nregions in the outer Galaxy were observed: IC1396, a region towards the Perseus\nArm, W3/4/5, and Gem OB1. The BGPS has detected approximately 8400 clumps over\nthe entire area to a limiting non-uniform 1-sigma noise level in the range 11\nto 53 mJy/beam in the inner Galaxy. The BGPS source catalog is presented in a\ncompanion paper (Rosolowsky et al. 2010). This paper details the survey\nobservations and data reduction methods for the images. We discuss in detail\nthe determination of astrometric and flux density calibration uncertainties and\ncompare our results to the literature. Data processing algorithms that separate\nastronomical signals from time-variable atmospheric fluctuations in the data\ntime-stream are presented. These algorithms reproduce the structure of the\nastronomical sky over a limited range of angular scales and produce artifacts\nin the vicinity of bright sources. Based on simulations, we find that extended\nemission on scales larger than about 5.9' is nearly completely attenuated (>\n90%) and the linear scale at which the attenuation reaches 50% is 3.8'.\nComparison with other millimeter-wave data sets implies a possible systematic\noffset in flux calibration, for which no cause has been discovered. This\npresentation serves as a companion and guide to the public data release through\nNASA's Infrared Processing and Analysis Center (IPAC) Infrared Science Archive\n(IRSA). New data releases will be provided through IPAC IRSA with any future\nimprovements in the reduction.\n