Optimizing point-source parameters for scanning satellite surveys
  We describe a method for deriving the position and flux of point and compact
sources observed by a scanning survey mission. Results from data simulated to
test our method are presented, which demonstrate that at least a 10-fold
improvement is achievable over that of extracting the image parameters,
position and flux, from the equivalent data in the form of pixel maps. Our
method achieves this improvement by analysing the original scan data and
performing a combined, iterative solution for the image parameters. This
approach allows for a full and detailed account of the point-spread function,
or beam profile, of the instrument. Additionally, the positional information
from different frequency channels may be combined to provide the flux-detection
accuracy at each frequency for the same sky position. Ultimately, a final check
and correction of the geometric calibration of the instrument may also be
included. The {\it Planck} mission was used as the basis for our simulations,
but our method will be beneficial for most scanning satellite missions,
especially those with non-circularly symmetric point-spread functions.
