TWAIO report Leiden University, July 1994

The Westerbork Northern Sky Survey

Martin Bremer

• Contents
• Introduction
  • The discovery of extraterrestrial radio sources
  • The first surveys
  • The importance of surveys
  • The WENSS survey
• The Observations
  • The WSRT array
  • The Mosaicing concept
• Reduction of the Data
  • The necessary hardware platform
  • Processing the data
    • Obtain processing information
    • Quality inspection of the data
    • Transferring data from optical disk to tape
    • Transferring data from tape to disk
    • Determine telescope offsets
    • Stability check of the gain and phase
    • Start of the reduction batch
  • The Mini Survey
  • Initial problems in the reduction
    • The position problem
    • The fluxproblem
    • The influence of strong sources in a map
• The Source Extraction
  • Introduction
  • The SAD routine
    • Technical details of the routine
    • Further processing
• The Catalogue
• Source Comparison
• Future Work
  • A new source extraction program
  • Solving the problems
  • Acknowledgments
• Bibliography
• About this document ...