Introduction to Asteroid PRO

This is a brief overview of the functionality of Asteroid PRO.

Asteroid PRO predicts and examines asteroidal occultations, the geometric alignment of an asteroid with a star such that the event, the brief disappearance of the star, is visible somewhere on earth. Actual observing and recording the event at sites across the occulting path can contribute significant information about the asteroid and star. Among the benefits are the determination of the size of the occulting asteroid, existence of asteroid satellites, diameters of stars, existence of close doubles, and other related phenomena.

Prediction of events consists of selecting an asteroid over a range of time in its orbit and determining whether its path as seen from earth passes sufficiently close to a star to cause an occultation. Further steps are necessary to determine exactly where and when on earth the occultation is visible, the visibility (altitude above the horizon and amount of darkness) of the event at each of the locations, the expected duration of the event, and the likelihood of the event occurring as predicted. Given the large number of asteroids and stars, literally thousands of events occur each month somewhere on earth, therefore, a key component in prediction is determining which few events are worth pursuing. Asteroid PRO is designed to provide a comprehensive, integrated set of tools to accomplish these tasks.

A large, current database of asteroids and their respective orbital elements, diameters, magnitude parameters and other information are supported. Version 1.7b contains over 5500 asteroids based on the highly accurate EMP database computed by the Institute for Theoretical Astronomy in Russia for the reference epoch of September 1994.

Version 2.0 updates the database to the current EMP set for the epoch of November 1996 and consists of 6160 numbered asteroids. Version 2.0 allows extension by user import of orbital elements and automatic ingesting of electronic orbital elements (MPEC) from the Minor Planet Center of the Smithsonian Astrophysical Observatory, Harvard.

Correspondingly, Asteroid PRO provides large stellar databases containing very accurate stellar positions and proper motions as well as other useful information such as spectral class. The primary stellar database is based on modern star catalogs, e.g. PPM and ACRS and others, representing the most accurate star positions available. Auxiliary files of stellar positions are supported to provide for occultations with stars not included in the main stellar databases.

A key element of asteroid occultation prediction is maintaining accurate asteroid orbital elements across the range of desired prediction dates. Static asteroid orbital elements are accurate for predictions of occultations at dates only very near (approximately two weeks) the epoch of the reference. Asteroid PRO provides extensive perturbation calculations throughout the program to integrate gravitational influences of the planets (and three large minor planets) on the orbital elements to provide an osculating orbital element set very near (e.g. within a day) the date of any occultation to guarantee that the resultant path of the occultation on the surface of the earth is as accurate as possible, limited mainly by the statistical errors in the original asteroid reference orbits and the positions of the stars, the former being the larger error at about 1 arcsecond, more or less.

Version 1.7b consists of over 340,000 stars from the North and South PPM (original catalog) catalogs supplemented by stars from the ACRS catalog. Version 2.0/Level I expands the stellar database to over 500,000 stars using the updated PPM catalogs and extensions, the ACRS catalog, the Carlsberg Meridian catalogs, and Lick Voyager series catalogs. All contain highly accurate positions and proper motions resulting in star coordinates which are ideally suited to occultation studies. Version 2.0/Level II adds 6,600,000 stars on CDROM selected from the Hubble Space Telescope Guide Star Catalog (to about magnitude 13.5). Although inherently less accurate than the above catalogs, its rich sky coverage provides a significant increase in the number of potentially interesting occultations. Asteroid PRO combines the frequent multiple catalog entries for many of the stars using a weighted average inversely proportional to the catalog error to improve the overall accuracy of many individual stars.

Asteroid PRO attempts to provide visual magnitude values for all the stars, converting when necessary from catalog photographic using formulae based on spectral classification where available.

The previous version, 1.7b, of the program requires Microsoft MSDOS 5.0 or later, a 386 or later compatible CPU, 40+ megabytes of hard disk and a mouse. A 386 math co-processor or 486 DX is highly desirable as well as a VGA color display. Version 2.0 will be available for Microsoft MSDOS and Windows. Version 2.0/Level 1 will require 50+ megabytes of harddisk. Version 2.0/Level 2 includes CDROM disk and contains over 300 megabytes of data and is particularly suited to DX4 and Pentium based systems.



  • Version 2.0 Level I $169.95
  • Version 2.0 Level II $199.95
  • Plus $5.00/$10.00 US/Non US Shipping

    VISA/MC/US Check

    The program consists of a Main Screen which allows access to the five main sections of the program. Two sections, Find Occultations and Browse Occultations, provide the main functions of looking for occultations and studying them, either during the search process itself or deferred by batching occultations into Browse Sets. Two sections, Lookup Asteroid and Lookup Star, access the two respective databases to provide additional functions or information about a specific asteroid or star. The remaining section, Distribution of Asteroids in the Sky provides some interesting information about the distribution and whereabouts of the asteroids in the sky.