Flux calibration of the AAO/UKST SuperCOSMOS H-alpha Survey
  The AAO/UKST SuperCOSMOS H$\alpha$ Survey (SHS) was, when completed in 2003,
a powerful addition to extant wide-field surveys. The combination of areal
coverage, spatial resolution and sensitivity in a narrow imaging band, still
marks it out today as an excellent resource for the astronomical community. The
233 separate fields are available online in digital form, with each field
covering 25 square degrees. The SHS has been the motivation for equivalent
surveys in the north, and new digital H$\alpha$ surveys now beginning in the
south such as VPHAS+. It has been the foundation of many important discovery
projects with the Macquarie/AAO/Strasbourg H$\alpha$ planetary nebula project
being a particularly successful example. However, the full potential of the SHS
has been hampered by lack of a clear route to acceptable flux calibration from
the base photographic data. We have determined the calibration factors for 170
individual SHS fields, and present a direct pathway to the measurement of
integrated H$\alpha$ fluxes and surface brightnesses for resolved nebulae
detected in the SHS. We also include a catalogue of integrated H$\alpha$ fluxes
for $>$100 planetary and other nebulae measured from the SHS, and use these
data to show that fluxes, accurate to $\pm$ 0.10 - 0.14 dex ($\sim$25-35 per
cent), can be obtained from these fields. For the remaining 63 fields, a mean
calibration factor of 12.0 counts pix$^{-1}$ R$^{-1}$ can be used, allowing the
determination of reasonable integrated fluxes accurate to better than $\pm$0.2
dex ($\sim$50 per cent). We outline the procedures involved and the caveats
that need to be appreciated in achieving such flux measurements. This paper
forms a handy reference source that will significantly increase the scientific
utility of the SHS.
