Goodbye to all that
This is the final cleaned-up image. How did we banish the
blizzard? First, we flagged sharp features appearing in one image
but not the other as cosmic-ray garbage and discarded them. Then
we combined the two "snow"-free images to improve the
signal-to-noise ratio. We also corrected for a number of
instrumental effects with names like "dark current," "flat
fields," and "charge transfer inefficiences." No need to bore you
with details of those effects, even though as a member of the team
that built the camera I spent a couple of years figuring out how
to characterize and remove them!
Despite all these efforts, some cosmic rays and other defects
remain that we need to jettison.