The VLA Galactic Plane Survey

The VLA Galactic Plane Survey (VGPS) is a survey of HI and 21-cm continuumemission in the Galactic plane between longitude 18 degrees 67 degr. withlatitude coverage from |b| < 1.3 degr. to |b| < 2.3 degr. The survey area wasobserved with the Very Large Array (VLA) in 990 pointings. Short-spacinginformation for the HI line emission was obtained by additional observationswith the Green Bank Telescope (GBT). HI spectral line images are presented witha resolution of 1 arcmin x 1 arcmin x 1.56 km/s (FWHM) and rms noise of 2 K per0.824 km/s channel. Continuum images made from channels without HI lineemission have 1 arcmin (FWHM) resolution. VGPS images are compared with imagesfrom the Canadian Galactic Plane Survey (CGPS) and the Southern Galactic PlaneSurvey (SGPS). In general, the agreement between these surveys is impressive,considering the differences in instrumentation and image processing techniquesused for each survey. The differences between VGPS and CGPS images are small, <6 K (rms) in channels where the mean HI brightness temperature in the fieldexceeds 80 K. A similar degree of consistency is found between the VGPS andSGPS. The agreement we find between arcminute resolution surveys of theGalactic plane is a crucial step towards combining these surveys into a singleuniform dataset which covers 90% of the Galactic disk: the InternationalGalactic Plane Survey (IGPS). The VGPS data will be made available on the WorldWide Web through the Canadian Astronomy Data Centre (CADC).