Re: Going, gone. Removed Sigma Squared.

[aah@nofs.navy.mil]

Chris wrote about coordinate units.  I'll give a couple of additional
comments and then stay quiet about the issue.
  (1) all fields that pertain to coordinates should be in the same units.
      It is just too easy to forget that conversion factor when writing
      a new piece of access software.
  (2) 64-bit floats don't care whether a number is 1.3E5 or 1.7E18.  The
      exponent can be >300.  It is only the human that cares, and this
      particular human finds it easier to compare raw numbers if they
      are in the same units.
  (3) While it is true that coordinates will be reported in degrees,
      errors are easier to understand in units of arcsec or even mas.
      Otherwise, you have several leading zeroes in the error fraction and
      have to increase the size of the display field.
      Yep, this violates my 'same unit' statement from #1, but in this
      case we are talking about displayed values rather than stored values.
It is your database software, and software can convert from one unit to
any other unit, so this is a pretty small point.  You can do whatever you
feel more comfortable with.
Arne