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I am trying to collect everything that might be needed for astronomy here. Feel free to drop me a message if you think there is something noteworthy to be added. Some of the files are hosted by myself, others will simply redirect to the corresponding site.

Astronomy Catalogs

Catalogs are used by Star Chart programs and platesolving apps (like DC3 Pinpoint). Some are easy to download, others are hosted on incredibly slow sites, and still others are simply too big to be downloaded.

  • USNO A2.0: A way more detailed catalog than GSC or UCAC 4 as far as star densities. The position data is not as accurate, but enough for classic platesolving applications. Located on, which is really slow. I made available a torrent file to download it, and I also put it on my server so you can download it (as a RAR archive). Please note that I don’t know if the original owners are happy about this or not, feel free to contact me if I should remove the data. USNO A2.0 torrent and USNO A2.0 RAR download.
  • Guide Star Catalog: Still useful, can be downloaded fromĀ
  • USNO UCAC 4: One of the newer catalogs, very good for astrometry, though has a lower star density than USNO A2.0. Can be downloaded fromĀ
  • USNO NOMAD: Extremely big, I am still looking for a source to download the whole thing. Anyhow, most programs support the on-demand download of required parts of the catalog, so as long as you have an internet connection you are fine.

Platesolving Applications

My indiscutable favourite is the all-sky platesolving application at It is a free service where you can upload your images, either as FITS or JPEG, and they will solve it really fast. Besides being free and fast, it is also able to solve the image without knowing its approximate location, so it is very useful if the usual platesolving applications fail.

Astrotortilla ( is using’s software to recreate the system locally on your computer. While it’s not as fast as the original, it is still very useful (and free). Beware, it requires a quite huge download of catalogs (depending on your field of view, the smaller the more data you’ll need).


I programmed a SafetyMonitor Wrapper for AAGWare’s CloudWatcher. I don’t know if there is any software out there (besides some beta versions) using it, but anyway. Feel free to use it, probabily the feature will be integrated in CloudWatcher soon enough. To install, run “regasm.exe” on it (you’ll find the file in your .NET framework installation).