This is a collection of files in xephem database format. Included here are
asteroids, comets, stars, deep-sky objects, earth satellites and spacecraft.
Work on the databases is a major project in itself. There are bound to be
errors. Authoritative contributions welcome.

The sample XEphem.ad resource settings assume the database files are in this
directory. For reference, the relevant resource is: XEphem.DBdirectory: edb



YBS.edb are all of the entries in the Yale Bright Star Catalog which have
a Bayer and/or a Flamsteed number. A few with common names have been renamed.
Contact the author if you would like the remaining stars (ecdowney@noao.edu).

Messier.edb is the Messier catalog.

Asteroids which can ever be at least mag 14 are in astorb.edb. They are named
with their sequence number followed by their common name, if one has been
assigned.

Deep-sky entries from the Saguaro Astronomy Club database Version 6.0 are in
SAC.edb. The NGC, IC, UGC and Messier objects have been moved into seperate
files. Some objects in the SAC database do not have well-accepted magnitudes.  
These entries are included but have special magnitude values of 99.9 or 79.9;
99.9 means no magnitude was available and 79.9 applies to dark nebulae.

IC is the Index Catalog culled from the latest NASA-ADC server (many thanks to
Christos Siopis, siopis@astro.ufl.edu). All NGC objects have been removed.

Orbital elements for several spacecraft are in spacecraft.edb. Updated by
Vance Haemmerle, vance@toyvax.Tucson.AZ.US.

Several comets are in comets.edb.

A typical Mir element set is in mir.edb just to serve as a handy example for an
earth satellite to try out.

VLA radio calibrator sources for several wavelength bands are in vla*cm.edb.

gps.edb are GPS satellite elements.


Also, as of xephem 2.9 the SAO, HD and PPM catalogs are now supported directly,
without the need for .edb files. See the Help for the Field Stars setup,
accessible from the Files menu in the Main window, for more information.


Format summary:

  name,type, then as follows:
 
  fixed format:
     RA, hours
     Declination, degrees
     magnitude
     reference epoch, optional, assumed to be 2000 if absent
     s = angular size, arc seconds, optional. Galaxies can also include minor
	 axis and position angle as additional subfields.
 
  elliptical format (e < 1):
     i = inclination, degrees
     O = longitude of ascending node, degrees
     o = argument of perihelion, degrees
     a = mean distance (aka semi-major axis), AU
     n = mean daily motion, degrees per day (computed from a**3/2 if omitted)
     e = eccentricity,
     M = mean anomaly (ie, degrees from perihelion),
     E = epoch date (ie, time of M),
     D = the equinox year (ie, time of i/O/o).
     g,k or H,G = magnitude model; select which by preceding the first field
 
  hyperbolic format (e > 1):
     T = epoch of perihelion
     i = inclination, degrees
     O = longitude of ascending node, degrees
     o = argument of perihelion, degrees
     e = eccentricity,
     q = perihelion distance, AU
     D = the equinox year (ie, time of i/O/o).
     g,k = magnitude model
     s = angular size at 1 AU, arc seconds, optional
 
  parabolic format (e == 1):
     T = epoch of perihelion
     i = inclination, degrees
     o = argument of perihelion, degrees
     q = perihelion distance, AU
     O = longitude of ascending node, degrees
     D = the equinox year (ie, time of i/O/o).
     g,k = magnitude model
     s = angular size at 1 AU, arc seconds, optional
 
  Earth satellite format:
     Epoch
     inclination, degrees
     RA of ascending node, degrees
     eccentricity, must be < 1
     argument of perigee, degrees
     mean anomaly, degrees
     mean motion, revolutions/day
     orbit decay rate, revolutions/day^2
     integral reference orbit number at Epoch
