GETEPH

GETEPH is a general ephemeris program written to be compatable with IDL. It can generate ephemerides for asteroids, comets, satellites, and planets and runs on the local network and at other, remote, locations, if the proper files are provided. The program accepts input lines one at a time. The format of the input line is:

JJJJJJJ.JJJJJ OOO CC IIIIIIIIII

The first letter of the ID is an object type code. Asteroids are specified with A (or a) or E (or e) codes. The E (e) option indicates an asteroid which is specifically given using the designation form used by Ted Bowell internally at Lowell. The A (a) option indicates an asteroid which is specified either in the standard MPC form or in the Bowell form. Thus we have E00XX123, or A2000XX123, or A00XX123. C or c are used for comets, P or p for a planet or satellite, T or t for a topocenter, and R or r for a relative ephemeris. More details are provided below. When running at Lowell only, the letter V or v may be used in place of A or a. This designation indicates that the vor files are to be searched first and then the emp files rather than the other way around. The actual data returned depends on the value of the output code CC. For codes less than 31, returned coordinates are X,Y,Z. For codes 31-45, the returned coordiates are X,Y,Z,XDOT,YDOT,ZDOT. Coordinates are in AU. Velocities are in AU/d.

If the object type code is A (or E), C, or P, then, the values returned as a function of CC are:

CC=0	The RA and Dec of date in radians.
CC=1	The RA and Dec of B1950 in radians.
CC=2	The RA and Dec of J2000 in radians.
CC=3	The topocentric equatorial coordinates (date) of the object.
CC=4	The topocentric equatorial coordinates (B1950) of the object.
CC=5	The topocentric equatorial coordinates (J2000) of the object.
CC=6	The topocentric equatorial coordinates (date) of the heliocenter.
CC=7	The topocentric equatorial coordinates (B1950) of the heliocenter.
CC=8	The topocentric equatorial coordinates (J2000) of the heliocenter.
CC=9	The ecliptic coordinates (B1950) of the object with respect to the barycenter of the solar systerm at JD uncorrected for light travel time.
CC=10	The ecliptic coordinates (J2000) of the object with respect to the barycenter of the solar systerm at JD uncorrected for light travel time.
CC=11	For A, E and C only, the elements (AM, AP, AN, AI, AE, AA) as well as q, Q, Period, epoch, and the variation in RA and Dec (rad) as well as the ephemis error (sec) (only if at Lowell).
CC=12	For A and E only, the errors in the elements (AM, AP, AN, AI, AE, AA) as well as q, Q, and Period.
CC=20	The combination of CC=0; CC=3; and CC=6.
CC=21	The combination of CC=1; CC=4; and CC=7.
CC=22	The combination of CC=2; CC=5; and CC=8.
CC=23	The combination of CC=2; CC=5; and CC=8 and CC=11.
CC=31	The ecliptic positions and velocities (date) of the object with respect to the barycenter of the solar system at JD uncorrected for light travel time.
CC=32	The ecliptic positions and velocities (B1950) of the object with respect to the barycenter of the solar system at JD uncorrected for light travel time.
CC=33	The ecliptic positions and velocities (J2000) of the object with respect to the barycenter of the solar system at JD uncorrected for light travel time.
CC=34	The ecliptic positions and velocities (date) of the object with respect to the heliocenter at JD uncorrected for light travel time.
CC=35	The ecliptic positions and velocities (B1950) of the object with respect to the heliocenter at JD uncorrected for light travel time.
CC=36	The ecliptic positions and velocities (J2000) of the object with respect to the heliocenter at JD uncorrected for light travel time.
CC=37	The equatorial positions and velocities (date) of the object with respect to the barycenter of the solar system at JD uncorrected for light travel time.
CC=38	The equatorial positions and velocities (B1950) of the object with respect to the barycenter of the solar system at JD uncorrected for light travel time.
CC=39	The equatorial positions and velocities (J2000) of the object with respect to the barycenter of the solar system at JD uncorrected for light travel time.
CC=40	The equatorial positions and velocities (date) of the object with respect to the heliocenter at JD uncorrected for light travel time.
CC=41	The equatorial positions and velocities (B1950) of the object with respect to the heliocenter at JD uncorrected for light travel time.
CC=42	The equatorial positions and velocities (J2000) of the object with respect to the heliocenter at JD uncorrected for light travel time.
CC=43	The invariable plane positions and velocities (date) of the object at JD uncorrected for light travel time.
CC=44	The invariable plane positions and velocities (B1950) of the object at JD uncorrected for light travel time.
CC=45	The invariable plane positions and velocities (J2000) of the object at JD uncorrected for light travel time.
CC=46	The ecliptic positions and velocities (J2000) of the object with respect to the heliocenter at JD uncorrected for light travel time (same as 36), followed by the 36 elements of the covariance matrix.

For an asteroid or comet (A or E or C), Incrementing a value by 50 will generate the same parameter result, but the input elements will be integrated to the requested JD before the ephemeris is calculated. For planets and topocenters (P or T), the result is unchanged by incrementing by 50.

If the object type code is R, then it is expected that it will be followed by two NAIF designators, separated by a ``-'' (e.g. R901-999). The resulting data is the position of the first object with respect to the second. In this case, the observatory is ignored, and the values returned as a function of CC are:

CC=3	The equatorial coordinates (date) of the first object with respect to the second object, uncorrected for light time.
CC=4	The equatorial coordinates (B1950) of the first object with respect to the second object, uncorrected for light time.
CC=5	The equatorial coordinates (J2000) of the first object with respect to the second object, uncorrected for light time.

If the object type code is T, then the topocentric values returned as a function of CC are:

CC=0	The topocentric RA and Dec of date of the topocenter are not a meaningful quantity.
CC=1	The topocentric RA and Dec of B1950 of the topocenter are not a meaningful quantity. As a result the RA and Dec are returned as -99.
CC=2	The topocentric RA and Dec of J2000 of the topocenter are not a meaningful quantity. As a result the RA and Dec are returned as -99.
CC=3	The topocentric equatorial coordinates (date) of the topocenter are all returned as zero.
CC=4	The topocentric equatorial coordinates (B1950) of the topocenter are all returned as zero.
CC=5	The topocentric equatorial coordinates (J2000) of the topocenter are all returned as zero.
CC=6	The equatorial topocentric coordinates (date) of the heliocenter.
CC=7	The equatorial topocentric coordinates (B1950) of the heliocenter.
CC=8	The equatorial topocentric coordinates (J2000) of the heliocenter.
CC=9	The ecliptic coordinates (B1950) of the topocenter with respect to the barycenter.
CC=10	The ecliptic coordinates (J2000) of the topocenter with respect to the barycenter.
CC=20	The combination of CC=0; CC=3; and CC=6.
CC=21	The combination of CC=1; CC=4; and CC=7.
CC=22	The combination of CC=2; CC=5; and CC=8.
CC=31	The ecliptic positions and velocities (date) of the topocenter with respect to the barycenter of the solar system at JD.
CC=32	The ecliptic positions and velocities (B1950) of the topocenter with respect to the barycenter of the solar system at JD.
CC=33	The ecliptic positions and velocities (J2000) of the topcenter with respect to the barycenter of the solar system at.
CC=34	The ecliptic positions and velocities (date) of the topocenter with respect to the heliocenter at JD.
CC=35	The ecliptic positions and velocities (B1950) of the topocenter with respect to the heliocenter at JD.
CC=36	The ecliptic positions and velocities (J2000) of the topocenter with respect to the heliocenter at JD.
CC=37	The equatorial positions and velocities (date) of the topocenter with respect to the barycenter of the solar system at JD.
CC=38	The equatorial positions and velocities (B1950) of the topocenter with respect to the barycenter of the solar system at JD.
CC=39	The equatorial positions and velocities (J2000) of the topocenter with respect to the barycenter of the solar system at JD.
CC=40	The equatorial positions and velocities (date) of the topocenter with respect to the heliocenter at JD.
CC=41	The equatorial positions and velocities (B1950) of the topocenter with respect to the heliocenter at JD.
CC=42	The equatorial positions and velocities (J2000) of the topocenter with respect to the heliocenter at JD.
CC=43	The invariable plane positions and velocities (date) of the topocenter at JD.
CC=44	The invariable plane positions and velocities (B1950) of the topocenter at JD.
CC=45	The invariable plane positions and velocities (J2000) of the topocenter at JD.

Running at Lowell

Asteroids -- At Lowell, the program accesses Ted Bowell's integrated asteroid orbit data base for multi-apparition asteroids and the non-integrated data base for single-apparition objects as well as the full version of the DE403 ephemeris. The program accepts numbered asteroids, temporary designation asteroids (including the A-type designation used until 1924), PL, T1, T2, or T3 objects. Examples are A1234 or E1234 (numbered); A1992AB12 or E92AB12 (temporary); AA1923BB1 or EA23BB1 (A-type); A1234P-L or E1234PL (PL object); A4567T-2 or E4567T2 (Tn object). Note that the leading A indicates that an asteroid ephemeris is desired and that the desination is given in standard form; the leading E indicates Ted's form. The elements are the nearest 100-day elements to the requested JD. The elements can be integrated to date if requested.

Comets -- At Lowell, as for asteroids, the program acesses the full integrated comet data base of comet orbits. Comets are specified either by their preliminary designation (ie 1993a1), by the Roman designation (ie 1993IV or 1987 XXIV), by the new preliminary designation (ie 1993A1 or C/1993 A1, by the permanent number (ie 111 or 83/P), or by the full name (ie P/halley or TEMPEL 2 or shoemaker). Full names are case insensitive. However the letter in the old style preliminary designation must be lower case; the roman designation must be upper case; the letter in the new style prelimiary designation must be upper case; and the type code (C/, P/, D/, etc) must be upper case. In all cases, the designation is preceeded by a lower or upper case letter c (C1993a; C1993IV; cP/halley). Note that non-periodic comets are not uniquely specified by a name (ie there are several shoemaker comets). If such a designation is given, the first one found in the file is used. It is best to specify a non periodic comet by an old-style preliminary designation, a new-style preiliminary designation or a roman designation.

Planets and Satellites-- The ID field is P followed by the planet ID number. The numbering scheme is taken from the NAIF system and is as follows:

0	Solar system barycenter
1	Mercury barycenter
2	Venus barycenter
3	Earth barycenter
4	Mars barycenter
5	Jupiter barycenter
6	Saturn barycenter
7	Uranus barycenter
8	Neptune barycenter
9	Pluto barycenter
10	Heliocenter
399	Earth geocenter
301	Moon
502	Europa
608	Iapetus

Thus, for example, a Pluto ephemeris can be requested by specifying P9 in the ID field, while a Lunar ephemeris is generated by specifying P301, and a Callisto ephemeris by P504, etc.

Running at Anderson Mesa or other remote locations

The files needed for running the program are described elsewhere. The biggest difference between the two locations is that the files at Lowell contain a very large database with osculating elements for every object on 100 day centers over a very large time range. This can really speed things up for historical calculations. The remote files contain a single set of osculating elements (for all objects) and the epoch of the elements is the nearest 100-day set of elements to the date on which the files were created. Users should not see any meaningful differences except for longer execution times at times away from the current epoch (particularly noticeable for near-Earth objects). Also, queries that involve information about the astrometric record will be incorrect off-site. The astrometry database is only accessible on-site at the Lowell Observatory Mars Hill offices.

Asteroid, comet and planet ephemerides can be generated off-site only within the dates supported by the limited range of the DE405 ephemeris file.

GETINFO

This program, like geteph, is a pipe. It's input is just the object code as described above for geteph. It will return, if possible, the full name of the object, H_v magnitude, G_v, and the reference for the orbit.