The 1.1 mm Bolocam Galactic Plane Survey

John Bally (Univ. of Colorado)

The Bolocam Galactic Plane Survey (BGPS) covers 170 square degrees of the northern Galactic Plane at a wavelength of 1.1 mm in the dust continuum. The survey was obtained with the 144 element Bolocam camera on the 10.4 meter diameter radio telescope at the Caltech Submillimeter Observatory.

The survey team is pleased to announce the release of the survey data and source catalog through the NASA/IPAC Infrared Science Archive (IRSA) at the Infrared Processing and Analysis Center (IPAC):

Millimeter-wavelength thermal dust emission traces the densest molecular gas most directly associated with the birth of stars and star clusters. BGPS probes a range of scales from cores in nearby clouds destined to produce individual stars and more distant clumps which may give birth to massive stars and star clusters. It will enable the investigation of the initial conditions of massive star and cluster formation without the biases inherent in source selection based on embedded infrared sources, HII regions, masers, or other signposts of on-going star formation.

The BGPS images and catalog provide an important database for future sub/millimeter observations. At wavelengths around 1 cm, the GBT has the same beam size as the CSO, making it an ideal instrument with which to probe the temperature and density of BGPS clumps using the 1.3 cm ammonia transitions. Spectral line, continuum, and polarization observations of BGPS clumps with the GBT will probe their grain properties, chemistry, and magnetic fields.

BGPS will serve as a finder chart for studies with ALMA and EVLA in the near future. High angular resolution line and continuum interferometry will determine when and how massive clumps fragment into star-forming cores, trace the flows of matter from molecular clouds onto clumps, cores, circumstellar disks, forming stars and planetary systems, and probe the feedback and self-regulation of star and cluster formation. ALMA and EVLA spectral line observations will measure velocity fields and trace chemical evolution. Continuum observations will identify young stars and probe the evolution of their ionizing radiation and resulting HII regions. The roughly 8400 clumps identified in BGPS will enable the investigations of the dependence of clump properties over the full range of Galactic environments from the Galactic center to the outer galaxy accessible in the anti-center direction.

The BGPS with an effective resolution of 33" FWHM provides contiguous coverage from -10.5 ≤ l ≤ 90.5, |b| ≤ 0.5 and is augmented with increased latitude coverage (to +/- 1.5 degrees) toward the Cygnus X region near l~80 and in four strips at l = 3, 15, 30, and 31. The area coverage of this section of BGPS is 133 square degrees. In addition, four targeted regions in the outer Galaxy were observed including IC1396 (9 square degrees), the l = 111 complex containing NGC7538 (4 square degrees), the W3/4/5 complex (18 square degrees), and Gem OB1 (6 square degrees). The survey has detected approximately 8400 clumps to an rms noise level ranging from 30 to 60 mJy/beam.

The Northern hemisphere BGPS compliments the southern hemisphere ATLASGAL survey at the APEX sub-mm telescope in Chile (Schuller et al. 2009) and covers most of the fields soon to be observed by the Hi-GAL consortium using the Herschel Space Observatory.

The data release includes fully reduced FITS map files, noise maps, and a catalog of sources produced by a custom catalog algorithm. BGPS sources are usually extended asymmetric structures, so the catalog reports source positions based on the maximum of emission in each source. The maxima are likely the best targets for follow-up observations of these millimeter continuum sources. Source centroids, sizes, and flux densities are also reported. Papers describing the data acquisition, reduction, and catalog production have been submitted to the ApJ (Aguirre et al. 2009; Rosolowsky et al. 2009) and are available from the IPAC site.

University of Colorado graduate student Adam Ginsburg used the BGPS data covering the Galactic center, combined with the Spitzer / IRAC, and VLA 20 cm radio continuum images to create a color composite which won the 2008 AUI/NRAO Image Contest and was featured in the 2009 AAS calendar.

The BGPS project is supported by the National Science Foundation through NSF grants AST-0708403 (U.C. Boulder) and AST-0607793 (U. Texas). Observing runs were partially supported by travel funds provided by NRAO.