Asteroid Plot
Suggestions and Help


ASTPLOT builds a plot that depicts the position of stars and asteroids within a defined region, typically the field-of-view of a telescope. The star positions derive from the USNO-A2.0 and PPM catalogs. The asteroid positions are supplied from the Lowell Observatory asteroid catalog and from orbits published in the Minor Planet Electronic Circulars.


Cookies are used to store default values for the user. Defaults are stored for the following parameters:

  1. Observatory Code
  2. Limiting Magnitude
  3. Minimum Probability of Imaging
  4. Field-of-View in RA
  5. Field-of-View in Decl
  6. Legend Suppression
  7. Motion Vector Length
  8. Ephemeris Uncertainty Length
  9. Asteroid Annotation Style

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Date Limits and Equinox

Users should not select dates outside the range 1890 to 2020. Asteroid positions are calculated using full planetary perturbations. All positions are ploted at equinox J2000.0.

Selection and Style Parameters


The plot is centered at the position (time and space) specified by the user. A small circle surrounds each asteroid's position (marked by a dot). A dashed line indicates the user-specified 1-sigma or 3-sigma uncertainty in the asteroid's position and an arrow represents the user-specified 1-day or 1-hour change in position of the asteroid (assumed linear). The asteroid's name is indicated near its nominal position. The observatory name, time of observation, and sky position are indicated at the top of the page. The radius of a plotted star/asteroid increases with brightness. All selected stars/asteroids fainter than 20th magnitude are plotted as 20th magnitude. North is plotted to the top of the plot and East is plotted to the left. Expect execution to take at least one minute; it may be longer if our server is busy.

Plots are produced in three formats: PostScript, compressed PostScript and JPG. The JPG plot is automatically displayed. The PostScript formats provide a higher level of detail than JPG but they require a PostScript viewer or printer. A PostScript viewer, ghostview, is available via ftp from (Unfortunately, ghostview is not in executable format so it also requires "tar", "gzip", "make", and a C compiler for you to build it.) The compressed version is about 20% as large as the uncompressed, so is valuable for those with slow links. The user must have "gzip" to uncompress the file. gzip is available from

Some problems in the USNO-A2.0 catalog are apparent in the plots. These include

© Lowell Observatory 2008
Web Curators: Ted Bowell & Bruce Koehn
Last modified: 2008 April 29