eph_type.txt

   Find_Orb can generate (at present) seven different types of ephemerides.

   About 90% of users will probably never generate anything except the
default 'Observables' ephemerides.  With these,  you can tabulate the RA/dec,
alt/az,  magnitude,  distance,  etc. for the target at desired times.

   In some cases,  it's useful to get ephemerides of state vectors.  These
will be relative to your 'location' : set it to 500,  and you get geocentric
state vectors;  set it to Sun for heliocentric,  or SSB for solar system
barycentric,  and so on.  If you've selected state vectors,  some options
specific to state vectors will be shown : you'll have a choice of distance
units (km, AU,  earth radii) and time units (seconds,  minutes,  hours,
days),  and can toggle between ecliptic or equatorial state vectors.

   Cartesian coordinates are effectively the same,  except that you get
x, y, and z,  with the velocity components omitted.

   The MPCORB option gets you orbital elements in the format used by MPC.
Unfortunately,  this is limited to elliptical heliocentric orbits,  and
they can't be very close to parabolic.

   The 'eight-line' option is considerably more flexible,  and provides
hyperbolic and non-heliocentric elements.  It's great for human readers,
though not at all good for automated use.  (I may add SOF output to give
a solution that is both human- and computer-friendly and that works with
all orbit types,  but getting other software to use SOF remains a problem.)

   If you select 'close approaches',  only the start and end times really
matter;  Find_Orb will look for instances between those times when the
distance from your 'location' to the target was a minimum.  Since the
'location' can be,  for example,  (Jup) or (Ven) or (Lun),  you can get
minima from those objects.  It's recommended that you not set your
location to be topocentric for this case.  If the object is not moving
more than about 0.5 km/s radially,  the earth's rotation will dominate
and you'll get a minimum once a day.

   On rare occasion,  it has been useful to be able to generate simulated
astrometry for an object.  The simulated observations are in ADES PSV
format,  and can be fed back into Find_Orb or any software that can
process ADES PSV data (which is probably more limiting than any of
us would really like.)

   Pro tip : while in the 'make ephemeris' dialog,  just hit (for
example) the two keys C 1 to switch to state vectors,  C 0 for
observables,  etc.  You need not touch the mouse.