Occult v4.6.0

Occultation Prediction Software
by David Herald

  1. What is Occult v4.6.0
  2. First Time Installation Instructions and Notes
  3. Updating Occult
  4. Copyright Issues


Occult is designed to generate occultation predictions, and analyse occultation observations, for a wide range of occultation phenomena, including:

  • occultations of stars by asteroids, planets, and planetary satellites
  • occultations of stars by the moon (including grazing occultations)
  • Solar and lunar eclipses, transits of Mercury and Venus
  • eclipses and transits of the satellites of planets against the planet
  • mutual eclipses and occultations of planetary satellites
  • mutual conjunctions of planets

In making these calculations, Occult uses many basic astronomical calculations. Many of these are made available for general use, such as:

  • ephemerides of the major planets, asteroids, comets and planetary satellites
  • graphics of planetary appearances and satellite configuration
  • moon phases, central meridians
  • diary of astronomical phenomena
  • rise/set times
  • calendar functions

To make these calculations, Occult provides for downloads of 42 separate data files which are subject to regular revisions. In addition Occult can use a number of star catalogues having file sizes of several GB (for example, UCAC4 with a size of 8.6GB).

The program is regularly updated, with a full list of the program changes being provided in Occult under the menu item Program updates - List version changes


    Occult v4 has been written in the language C#, and runs in the .NET framework V4.5. To run Occult you must have the .NET Framework V4.5 installed on your computer. The .NET Framework V4.5 is not supported in Windows XP - which means you can not run this version of Occult on XP. If you have been running OccultWatcher, the .NET V4.5 framework is present on your computer.

    Windows is distributed with the .Net framework. If your computer does not have V4.5 of the .Net framework, you will get a Windows message about this when you run Occult. Do not be concerned. Simply follow the link provided in that message to install the .Net framework V4.5.

You need to download and save (use right click on your mouse and select "Save target as"):

    When you first run Occult (see below) Occult will download two zip files to complete the installation. If you plan on installing Occult on a computer that does not have internet access, you can separately download and save the following two data files [but do not unzip them]. However it is easier if you let Occult handle the downloading...:

To install Occult:

  • Create a directory where you want to install Occult. [You might call it 'Occult 4']. This directory can be located anywhere.
  • Unzip the 11 files in occultinstaller.zip into that folder
  • Create a desktop shortcut to the Occult.exe file
  • If you have created the Occult directory in the Program Files or Program Files (x86) directory - right-click on the shortcut; select Properties; select the tab 'Shortcut'; click 'Advanced'; check 'Run as administrator'
  • [OPTIONAL - if you have downloaded installresources.zip and installsites.zip]. Copy or move those files into that same directory but do not unzip them

Now run Occult. Occult will complete the installation by creating a number of subdirectories, downloading the two data files (unless you have already downloaded them and placed them in the Occult directory), and unzip them into the relevant directories. Occult will then take you to a page that displays a range of default settings. You can change the settings here at any time after Occult has been installed. However at this stage you should do the following:

  • insert your site details in the box Site details low precision;
  • insert your email address for the FTP anonymous password in the box FTP URL;
  • insert the details of your email SMTP server. This is required to allow observations to be emailed from within Occult
  • indicate whether GoogleEarth is installed on your computer, in the GoogleEarth box;

You will then be taken to the download page, where you can download the latest versions of a number of data files - including some large catalog files. The files that need to be downloaded will be tagged with a chevron. However you do not need to download them immediately.

Finally you will be taken to the main form of Occult, where you can use its functionality.

To assist you in learning how to use the program, the Help file system includes a topic First time user - examples. You should work through each of the examples under this topic - to become familiar with how the program works, and the functions that are available. [If you can't access the Help topics, click the menu item Help... if Help not working on the main form of Occult for instructions on how to fix the problem]


When you run Occult, the existence of updates will appear at the bottom-left of the main form. To update, simply click the update text. The frequency at which Occult will check for updates is set in the User Settings, which are accessed from the Maintenance tab of Occult. You can manually check for updates using the Menu item Program updates...

If for some reason you need to do a manual update of the program files:

  • download Occult update
  • unzip this file into the directory where you have installed Occult, replacing the files of the same name. [You might want to make a backup of your existing version of these files, just in case something goes wrong....]. The files are:

    • AutoAsteroidPrediction.exe
    • AutoAsteroidPrediction.exe.config
    • LightCurveSimulator.chm
    • Occult.chm
    • Occult.exe
    • Occult.exe.config
    • Occult.SDK.dll
    • OccultUpdater.exe
    • OccultUpdater.exe.config
    • OccultUtilities.dll
    • OccultUtilities.dll.config

Tips for using Occult by David Dunham (pdf file)


Occult relies heavily on data that is freely available. Items such as various star catalogues and the planetary ephemerides have been developed by government funded agencies or grants. Occultation and graze observations have been contributed mainly by the efforts of amateur astronomers (or as I prefer to call them, unpaid astronomers) from around the world. This contribution needs to be recognized and acknowledged.

The philosophy behind my writing and maintaining Occult is to encourage useful observations of occultation phenomena, thereby increasing our knowledge of the world around us. Accordingly:

  • Users of Occult are free to disseminate predictions or results generated by Occult in a non-commercial manner, provided it is in a context of encouraging (directly or indirectly) observations of occultation phenomena. All I ask is that wherever possible there is an acknowledgement that the data was generated by Occult.
  • In circumstances where there is a desire to include Occult predictions or results in a commercial publication, you may do so provided (i) it is in a context of encouraging (directly or indirectly) observations of occultation phenomena, and (ii) it is a minor part of that publication (eg a one or two page column in a 50-page monthly magazine). The fact that the predictions or results were generated by Occult4 should be acknowledged.
  • Where the success of a commercial publication is likely to be dependent upon the output from OCCULT, you do not have automatic permission to include Occult outputs in that publication. You will need to contact the author and seek written permission.
  • Where the output of Occult is displayed on GoogleEarth, GoogleSky or GoogleMaps, you will also need to comply with any copyright issues associated with those products.

For the record, I reserve all rights to the Source code and any decompilation thereof - but with IOTA being able to continue to maintain/improve the program on the same basis as above, when I am no longer in a position to do so.

Dave Herald
March 2018

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