[AstroPy] Coords v0.25 release now available

Victoria G. Laidler laidler at stsci.edu
Thu Jan 25 13:58:05 CST 2007


Version 0.25 of the Coords package has been released and is now 
available at
http://stsdas.stsci.edu/astrolib/. This is a bugfix release.

Release notes:

The following issues have been addressed:
- Negative degrees in sexagesimal specification is now handled
- Longitude/RA convention for TPM-based method calls is now
consistent with the rest of the package
- Example text has been updated



An explanatory note about time:

There are three times of interest associated with a celestial
coordinate. TPM calls these
- the equinox == time at which precession is zero
- the epoch == time at which proper motion is zero
- the timetag of the coordinate

At present (v0.25), the Coords package enforces equinox=B1950 for
galactic coordinates and J1984 for ecliptic coordinates; celestial
coordinates may be specified at J2000 or B1950, or at an arbitary
Julian (decimal) year. For all coordinate systems, it enforces
epoch=J2000 and timetag="time now" -- that is, it uses the current
system time.

Galactic and celestial coordinate systems are very insensitive to
changes in "time now", but due to the nature of the ecliptic reference
frame, ecliptic coordinates are quite sensitive.

The v0.3 release of the Coords package is planned to include the
ability to specify the timetag of the coordinate.


Release history:
- v0.2: included TPM capability to handle precession
- v0.1: initial release



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