Here's what happens in the registry (concerning cel links) when celestia is installed on windows machine (if option for cel links is checked):

  1. CreateKey HKCR\cel (create new key in HKEY_Classes_Root named cel)
  2. SetValueEx HKCR\cel "URL:Cel Protocol" (set default string value for this key to URL:Cel Protocol)
  3. SetValueEx HKCR\cel\URL Protocol "" (create new string value named URL Protocol and set to null)
  4. Createkey HKCR\cel\Shell (create new key under Cel)
  5. SetValueEx HKCR\cel\Shell "" (set default string value to null)
  6. Createkey HKCR\cel\Shell\open (create new key under Shell)
  7. SetValueEx HKCR\cel\Shell\open "" (set default string value to null)
  8. Createkey HKCR\cel\Shell\open\Command (create new key under open)
  9. SetValueEx HKCR\cel\Shell\open\Command "C:\Program Files\Celestia\celestia.exe --once --dir "C:\Program Files\Celestia" -u "%1"" (set default string value to C:\Program Files\Celestia\celestia.exe --once --dir "C:\Program Files\Celestia" -u "%1")

Note: Omitted Closekeys and Querykeys for readability.

So what you end up with in your registry is: