Scantable vs MS

Issues

• changing ASAP to use MS underneath means rewriting almost all methods
• Scantable stores polarisations individually, MS stores them in a matrix
  • no referencing possible - requires copying
• Scantables stores Coordinates (per band), MS stores per channel informations
• MS is overkill for SD data

Solutions

• write direct MS -> Scantable filler
  • only copy when necessary
  • faster
  • both are based on casa::Table so clever things can be done
  • all non-asap relevant information could be copied/referenced
• write Scantable -> MS writer
  • preserve all (most) information/meta-data