Below are commands related to using the built-in object databases and orbits.

find

Syntax: find objectname

This command searches the built-in object databases for "objectname" and sets the RA and DEC variables accordingly. The built-in databases include bright stars (by name), the Yale Bright Star Catalog (YBSC), the Tycho-2 Catalog, Messier and SAC deep sky database (includes NGCs, many ICs, etc.).

The YBSC supports HR, HD, and SAO catalog prefixes. To search for a Flamsteed number, use the format: "F XX CON" where XX is the Flamsteed number and CON is the containing commonly used three letter constellation abbreviation. To search for a Bayer designation, use the format: "B GGG CON" where GGG is the three letter Greek letter abbreviation and CON is the containing commonly used three letter constellation abbreviation.

The Tycho-2 catalog supports HD, HIP, and TYC prefixes. When the TYC prefix is used, the suffix is in the format 'bbbbcccccs", where 'bbbb' is the block number, 'ccccc' is the star's catalog number, and 's' is the star number. The correct number of digits must be used.

To "search" for a specific RA and Dec position, use the format "#hhh.hhh,ddd.ddd" or "#hh:mm.m,+dd:mm" or "#hh:mm:ss,-dd:mm:ss". "#" is the prefix followed by the RA and Dec, separated by a comma, in either decimal, hours/degrees and minutes, or hours/degrees and minutes and seconds format.

The variable FINDERROR is set to "true" if the object is not found.

findneareststars

Syntax: findneareststars rank min_mag max_mag max_distance <use_tycho-2_stars>

This command searches the stellar database (the Yale bright star catalog or the Tycho-2 catalog if "use_tycho-2_stars" is true) to find stars near the position specified by the variables RA and DEC that are greater than "min_mag" and less than or equal to "max_mag" and no farther away than "max_distance" angular degrees. If "rank" is 0, the variable STARCOUNT is set to the number of stars found, otherwise for the "rank'th" nearest star, the variables RA and DEC are set to its position and the variable SEPARATION is set to its angular distance. If there no "rank'th" star, the variable STARCOUNT is set to 0.

Note that the YBSC catalog contains stars as faint as magnitude 6.5 (uniformly) and the Tycho-2 goes as faint as magnitude 12-13 (non-uniformly).

findbrighteststars

Syntax: findbrighteststars rank min_mag max_mag max_distance  <use_tycho-2_stars>

This command searches the stellar database (the Yale bright star catalog or the Tycho-2 catalog if "use_tycho-2_stars" is true) to find stars near the position specified by the variables RA and DEC that are greater than "min_mag" and less than or equal to "max_mag" and no farther away than "maxdistance" angular degrees. If "rank" is 0, the variable STARCOUNT is set to the number of stars found, otherwise for the "rank'th" brightest star, the variables RA and DEC are set to its position and the variable SEPARATION is set to its angular distance. If there no "rank'th" star, the variable STARCOUNT is set to 0.

Note that the YBSC catalog contains stars as faint as magnitude 6.5 (uniformly) and the Tycho-2 goes as faint as magnitude 12-13 (non-uniformly).

loadorbits

Syntax: loadorbits orbitfilename <append>

This command loads into memory the orbital elements for up to 25,000 comets and asteroids from the file "orbitfilename". This file is to be formatted in the orbit format used by The Earth Centered Universe planetarium software. If the optional parameter "append" is "true" then the currently loaded orbit database is retained and the new database is appended, otherwise the currently loaded database is deleted before loading the new orbits. The variable ORBITERROR is set accordingly. The variable ORBITSLOADED is set to the total number of orbits loaded.

saveorbits

Syntax: saveorbits orbitfilename

This command saves the orbital elements currently in memory to the file "orbitfilename". This file is to be formatted in the orbit format used by The Earth Centered Universe planetarium software. The variable ORBITERROR is set accordingly.

findorbit

Syntax: findorbit orbitname

This command searches the currently loaded orbits (comets and asteroids – see loadorbits command) for "orbitname" and if found the variables RA and DEC are set to its current position, the variable "ORBITMAG" is set to its magnitude, the variable "ORBITNAME" is set to its full name, and the variable ORBITNUMBER is set to the orbit number used by the orbitradec command. Spacing and case does not matter. In addition, their fullnames can be shorted such that, for example:

  • Comet "C/2015 W1 (Gibbs)" can be found using its designation "C/2015W1"
  • Comet "127P/Holt-Olmstead" can be found using just "127P"
  • Asteroid "(117032) Davidlane" can be found using either "(117032)" or "Davidlane"
  • Asteroid "(164221) 2004QE20" can be found using either "(164221)" or "2004QE20"

clearorbits

Syntax: clearorbits

This command removes all orbital elements currently stored in memory. The variable ORBITSLOADED is set to 0.

searchorbitsbyname

Syntax: searchorbitsbyname orbitfile orbitname <append> <numberedonly>

This command searches the orbital elements contained in the file "orbitfile" whose full or partial orbit name matches "orbitname". The case is ignored. The results are stored in memory (and accessible with findorbit, orbitradec, and saveorbit commands. If "append" is false or not specified, the currently loaded orbits are removed first, otherwise if "true", the newly found orbits are appended to the currently loaded ones (until the maximum of 25,000 orbits). If "numberedonly" is true, the search is limited to the IAU numbered asteroids - those formatted as "(###) Name". If an error occurs reading the orbit file, the variable ORBITERROR is "true". The variable ORBITSFOUND is set to the number of orbits found. The variable ORBITSLOADED is set to the total number of orbits loaded.

searchorbitsbyposition

Syntax: searchorbitsbyposition orbitfile ramin ramax decmin decmax magmax <append> <numberedonly>

This command searches the orbital elements contained in the file "orbitfile" whose position at the current time is contained within the range of right ascension from "ramin" to "ramax" and the range of declination from "decmin" to "decmax" and not fainter than magnitude "magmax".

The results are stored in memory (and accessible with the findorbit, orbitradec, and saveorbit commands. If "append" is false or not specified, the currently loaded orbits are removed first, otherwise if "true", the newly found orbits are appended to the currently loaded ones (until the maximum of 25,000 orbits). If "numberedonly" is true, the search is limited to the IAU numbered asteroids - those formatted as "(###) Name". If an error occurs reading the orbit file, the variable ORBITERROR is "true". The variable ORBITSFOUND is set to the number of orbits found. The variable ORBITSLOADED is set to the total number of orbits loaded.

convertmpcorbits

Syntax: convertmpcorbits inputfile outputfile

This command converts orbits in the IAU's Minor Planet Center's minor planet format into the format used natively by ARAP and The Earth Centered Universe planetarium software. The input file is specified by "inputfile" and the output file is specified by "outputfile". The variable ORBITSCONVERTED is set to the number of orbits converted. If an error occurs reading or writing files, the variable ORBITERROR is "true".

Note: you can use the httpgetfile command to download orbit files from the Minor Planet Centre.

The download link for all minor planets is here: https://www.minorplanetcenter.net/iau/MPCORB/MPCORB.DAT