[Photograph of the CGPS field in the Milky Way]

Introduction

Understanding our origins, ultimately from diffuse gas and dust in the interstellar medium (ISM) of our Galaxy, represents one of the most compelling challenges in natural science. Success in this endeavor depends crucially upon deciphering the mysteries of the Galactic ecosystem, where counterbalancing, often violent, forces have shaped the ISM and star formation within it over time.

The Dominion Radio Astrophysical Observatory, in collaboration with a consortium of university astronomers, has begun a high-resolution survey of the atomic hydrogen and radio continuum emission from our Milky Way galaxy. By constructing a mosaic of 190 synthesis fields, the survey will cover Galactic longitudes from L=74.2 to 147.3 degrees and latitudes from B=-3.6 to +5.6 degrees, resolving features as small as 1 arcminute. Within this region the observations will yield an atomic hydrogen ``cube'' with 256 channels and velocity resolution 1.2 km/s, Stokes I, Q, U and V continuum polarization images at 1420 MHz, and a Stokes I continuum image at 408 MHz.

These observations form the centerpiece of the CGPS, an international collaboration to map all of the major interstellar components of the Milky Way at a common resolution: neutral atomic gas, molecular gas, ionized gas, dust grains, and relativistic plasma. For many of these constituents, angular resolution will be improved over previous studies by more than a factor of 10. The principal goal of the project is the creation and scientific analysis of a database of panoramic, high resolution images of all the major components of the ISM.

This effort is possible only now because of the convergence of new technical developments. A Pilot Survey Project was carried out prior to the full survey to evaluate mosaicing issues at DRAO. Imaging of the molecular phase of the ISM, traced by the CO molecule, has recently been realized at the Five College Radio Astronomy Observatory. High-resolution IRAS images of the dust component, seen through its infrared emission, have been completed at far-infrared wavelengths at the California Institute of Technology, and in the mid-infrared at the Canadian Institute for Theoretical Astrophysics at the University of Toronto. Complementary radio continuum images at frequencies below 408 MHz are being contributed by the Mullard Radio Astronomy Observatory of the University of Cambridge and at the Beijing Astronomical Observatory.

Summary of CGPS Data

(Alternative form available for table-challenged browsers)
FrequencyWavelength ObservationISM ComponentSource
151 MHz190 cm     Continuum (I) Ionized Gas
and
Relativistic
Plasma
MRAO
232 MHz130 cm     BAO
327 MHz 92 cm    
408 MHz 74 cm     DRAO
 1420 MHz 21 cm    
Continuum (QUV)Magnetic Fields
H Spectral LineAtomic Gas
115 GHz2.6 mm     CO Spectral LineMolecular Gas FCRAO
3 THz100 µm     Continuum (I)Dust Grains Caltech
5 THz 60 µm    
12 THz 25 µm     Very Small
Dust Grains
& PAHs
CITA
25 THz 12 µm    


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