How to import the Bowell asteroid orbital elements file within C2A?

C2A is able to read the full Asteroid Orbital Elements Database from Ted Bowell (see and display the position of one or several asteroids from this database. To do this, proceed as follows:

1. First, download the compressed version of the Astorb.dat file from (click the link at the end of the sentence "Get a decompressed version (Astorb.dat) via ftp by clicking on here".

You will get a large file called astorb.dat.gz which is 36 MBytes large, so it may take a while to download. Uncompress this file and store the resulting file Astorb.dat in a directory of you choice.

2. Once the Astorb.dat file is uncompressed, launch C2A for Windows and open the Asteroids & Comets Tool from the Tools menu (Ctrl+A is a shortcut).
3. In the Asteroids & Comets tool, click the Import... button.

4. In the Import dialog box, select first the Asteroids radio button, then pick the "Bowell Format" in the Format combo box. Finally, select the source option "From File" and locate the Astorb.dat file you have previously downloaded using the small "..." button on the right side of the text zone.

Close the Import tool using the OK button.

5. Because of the the large number of asteroids in the database, it might take a while to import all the orbital elements (possibly several minutes). A message is displayed in the dialog zone of the tool.
6. All the objects cannot be displayed in the asteroid list (there are just too many of them...), so you will get a message at the end of the Import process stating that all asteroids cannot be displayed. However, all the asteroids are loaded and you can use the Filter... button to display the asteroid(s) you want in the list.
7. Using the Filter... button, you can restrict the number of asteroids to be displayed in the list. For instance, you can ask to display only the asteroid Antiope.
8. Select the Antiope asteroid in the list and activate the Position check box at the bottom left of the tool. Clock Go to to center the map on the asteroid and Apply to save all the changes.

To clear the asteroid list (it can slow down C2A when you launch the program), use the Clear button in the Asteroids & Comets tool.

Note that only the steps 1 to 5 are required if you want to load the Astorb.dat file in order to use it with Occult Watcher.