The Westerbork Synthesis Radio Telescope (WSRT) in the Netherlands has been used to survey a section of the galactic plane at a radio frequency of 327MHz. Twenty-three overlapping synthesis fields were observed, covering galactic co-ordinates |b|<1.6d, 43d < l < 91d. Each field was observed at two epochs, several years apart, to identify variable sources. Intensity data from the seperate epochs were combined, and the resulting images mosaiced to produce a single image of the entire survey region. Sensitivity of the mosaic is typically a few mJy. Resolution is 1' by 1'csc(dec).
The survey image provides our first high resolution view of the Galaxy at low radio frequencies, and includes sections of the Sagittarius and Cygnus arms. These sections contain numerous extended features, among them supernova remnants, HII regions, "bubbles" of thermal emission, and large patches of amorphous galactic thermal emission. The inter-arm region is characterized by lower densities of extended features, but numerous discrete compact radio sources, most of which are background objects such as quasars and other types of active galactic nuclei. However, the resolution, sensitivity and low frequency of this survey make it ideal for detecting weak, non-thermal compact galactic sources, e.g. compact, low surface brightness SNRs and radio stars.
The image at the top of this page shows a low-resolution overview of the entire survey. Subimages of the survey are available below, each covering roughly 7 degrees of Galactic longitude.
For more detailed information on the survey project and statistical analysis of the compact source population, please refer to:
Taylor, A.R., Goss. W.M., Coleman, P.H., van Leeuwen, J. & Wallace, B.J. 1996, Astrophysical Journal Supplementary Series, 107, 239.
to the University of Calgary Radio Astronomy Lab Home Page.