Ephemeris tracking of small bodies is possible, after supplying the orbital elements to the ephemeris program. Up to four objects may be stored at one time.
Before you begin, ensure that you have all the orbital elements you will need and ensure that they are J2000 elements! For comets, you'll need to convert the time of perihelion passage (T) to Julian Date form. Finally, be aware that there is no "update" option - the only way to update an object is to replace it with new elements, and you will have to re-enter all the elements, not just the one(s) you are changing. If you store two different sets of elements for the same object, you will need to give them two different names to keep the record straight.
The program, CEPH, can be accessed from the observatory as well as remotely. From the observatory, sitting at the console, issue the command START CEPH A14, and then follow the prompts which appear on the MODGRAPH terminal. If you are observing remotely, first open both mterm and mterma windows. In your mterm issue the command START CEPH A04, and follow the prompts on the mterma window. From there on the procedure is the same.
You'll see "CURRENT CONTENTS OF COMET/ASTEROID FILE" displayed. Select an object from the current list which you wish to replace. You'll be prompted for the desired input device (in this case option 1 = TERMINAL). Enter the number of your selected object, and the type of object. "TYPE" determines whether you will be prompted for "time of perihelion passage" (comets) or "mean anomaly" (asteroids) elements. Then you will need a name (in 12 characters or less, it may include numbers but the first character must be a letter) for the object, this will be your identification string for the object, so record it carefully.
You are then prompted for the elements, in the form you've specified. For example, in the comet case, these are inclination (i), longitude of ascending node (big Omega), argument of the perihelion (little omega), eccentricity, time of perihelion (T) in JULIAN DATE, and perihelion distance (q). The entered values are displayed on the screen for your approval: "IS EVERYTHING CORRECT ?" If they are what you meant to enter, enter "Y" and the job is complete. The program completes with a signoff message, "COMET EPHEMERIS UPDATE PROGRAM EXITTING . . ."
To begin tracking the comet,
issue the command
COMET COMETNAME
(this is why you had to remember what you named it).
Even if the object is an asteroid, the command
is COMET. Tracking in this manner will automatically rotate the dewar so
that the sun-tail axis of the comet is aligned along the horizontal axis
of the array, and the VLSR will automatically be set. Check the positions,
angles, and velocities carefully against your ephemeris to ensure that
everything is entered correctly. (For example, the values on SCREEN 1
for VSUN and VCOR should sum up to your predicted geocentric velocity
(deltadot).