TheSky supports the Gaia Star Catalog

Be sure to maintain your software subscription to get access to the latest software updates!

What is the Gaia Star Catalog?

The European Space Agency’s over seven year and counting Gaia satellite observation mission is producing the largest and most accurate star catalog on record, with precision astrometric, photometric and spectroscopic measurements on, at present, almost 1.7 billion stars. The current officially release catalog data is called Data Release 2 (DR2). 

Not quite billions, and billions of stars, but getting closer!

A recently released update to TheSky Professional Edition displays Gaia stars with positions to the milliarcsecond, G/BP/RP mean magnitudes, spectral class, star distance in light years, stellar temperature, and proper motion.

Why do I need Gaia stars?

In a nutshell, the more accurate the star catalog’s positions, the more accurate your measurements based on these stars will be.

Whether you’re using TheSky’s Image Link to perform an Automated Pointing Calibration and produce a TPoint Super Model that improves your telescope’s pointing and tracking, running a script that finds the astrometric position of double star companions, or studying dynamic nature of stellar proper motion for the past thousand years, you can count the Gaia catalog.

The Gaia Star Catalog

The entire Gaia DR2 catalog consumes over 1.2 TB of disc space and can be downloaded from the Gaia archive page.   When the complete catalog is present, TheSkyX Professional Edition’s Sky Chart displays every star from the Gaia catalog and the accompanying “metadata.”

If you do not have a super-fast internet connection, or do not want to clutter your computer’s drive with unnecessary data you may not use, TheSkyX Professional Edition includes more easily distributed subsets of the Gaia star catalog that should suit the needs of most.

  • The larger Gaia subset contains the RA, Dec, magnitude, spectral class and proper motion for 1.7 billion stars.
  • The smaller Gaia subset contains about 100 million stars equally distributed across the celestial sphere and is ideal for determining the astrometric solution for photos as small as about 3 arc minutes across.

Table 1: Gaia Catalog Subsets

Catalog NameNumber of StarsLimiting
Free Disc Space
Larger Gaia Subset1.7 billion~1994
Smaller Gaia Subset100 millionn/a* 5

* Not applicable. TheSky’s Smaller Gaia Subset database was created to have a relatively equal distribution of stars across the entire celestial sphere. This ensures that the astrometric solution can be found for most optical systems in photos taken anywhere in the sky. While there are some 18th magnitude stars, we don’t publish a limiting magnitude for the small Gaia subset.

Minimum System Requirements

  • TheSkyX version 10.5.0 build 12940 and later is required to display Gaia data.  Choose the About TheSky command (Help menu on Windows/Linux, TheSkyX menu on macOS) to make sure you have a compatible version installed.  If not, click Help > Check for Updates and install the latest daily build.
  • The Database Add On SSD Version 3 and later includes the small and large Gaia subset databases.
  • The small subset can be downloaded here.


Q. I already own TheSky Professional or TheSky Imaging and my subscription is up to date. How can I get the Gaia star catalog?

A. First, install the latest daily build from My account > My Downloads. Next, download the Gaia subset and follow the instructions on the Gaia subset download page to view them. If you want the Large Subset, purchase the Database Add On.

Q. How do I configure TheSky to use the Gaia data?

A. Please see TheSky User Guide here for details.

Q. Does TheSky support the Gaia Data Release 3 (DR3)?

A. TheSky will support the Gaia DR3 when it is released. The current release estimate is sometime in the first half of 2022. While an the early DR3 is available now, we’ll wait for the official release to supporting it.