Re: TASS Database, Store ra,dec Sigma or not?

[aah@nofs.navy.mil]

  I disagree with Michael (that's ok, isn't it?).
  We need coordinate sigmas to be sure that an object is properly matched
with a mag16 object, for moving objects, etc.  The easiest way to calculate
the coordinate errors for the master tass_cat catalog is to have three fields:
number_observations, sum_coordinate and sum_coordinate^2.  Then, at any time,
one can calculate the errors from those three quantities.  Unfortunately,
the sums have to be 64-bit floats to get the proper scaling and precision;
the number_observations field can certainly be a 16-bit integer.
  Sorry -- my philosophy with scientific data is to always quote errors
with any published value.  If it requires extra storage in the master
catalog, then I feel it is a necessary evil.
Arne