JSkyCalc portal


JSkyCalc is a portable and easy-to-use tool for doing the “time and the sky” calculations encountered in planning and executing astronomical observations.  You can use it before an observing run to assess the visibility of your targets through the night, their proximity to the moon, and so on; at the telescope, it is invaluable for selecting targets on the fly. While it superficially resembles desktop planetarium programs, its feature set is optimized for professional astronomers.

The purpose of this page is to provide a (hopefully) stable address for the most recent versions.  It is currently under construction, but I intend to link here:

  • The standard JSkyCalc in the form of an executable jar file.
  • A large-type version of the same program, designed for legibility on displays with very fine dot pitch.

New features:

  • For Linux and Mac only, you can automatically pop a ds9 image-display window, download a Digital Sky Survey image of your coordinates, and automatically mark up the image as a finder chart. (This uses XPA, a program distributed along with ds9.)
  • A URL linking to further information about an object (e.g., a finding chart) can be included in the target list; a single button-push sends this URL to a browser.
  • Target lists can be in comma-separated variable format and accept decimal degrees.

JSkyCalc is written in java, which requires the Java Runtime Environment to run.  This is apparently standard on Macs, and is easily installed on Linux and Windows machines.  Installation of JSkyCalc should be as simple as downloading the executable.  If you would like to install a custom site not on the rather limited site menu, it is not difficult to unpack the executable jar file and edit the file from which the site parameters are read.