# Looking for star database

I am looking for a particular set of information to essentially make a star map for a game.

What I need:
All stars within 11,462 light years of Earth.
Their stellar classification.
If they have any planets around them (hypothetical or otherwise)
Their position using an x, y, z coordinate relative to earth or galaxy center (I don't really get declination, etc)

I need the extrapolated position/distance data, not the catalogs themselves.

The best one I can find is HYG, HabCat, and HYGHag is limited to to like 120,000 of 1,2 billion estimated stars... Are there any better?

• Are you sure that you want a volume-limited catalog ("all stars within X light years"), and not a flux-limited catalog ("all stars which appear brighter than X as seen from Earth") ? Google for the Hipparcos catalog to get 3D positions of brighter stars. – mtewes Sep 2 '16 at 9:19
• All is what I "want"... Cuz I like to keep as close to "reality" as possible, but minimally I need all stars within 100ly of Earth for anothe reason too. – Durakken Sep 2 '16 at 9:28
• This is going to be a lot of work on your part to compile something like this. All this information, in this format, is not going to be compiled easily. Likely you'll need to use several sources and do a lot of converting. A good place to get exoplanet data is exoplanet.eu where you can download all their data. However, it will require significant work to match up their star names with stars from other catalogues. Often a single star will have many different names, depending on what catalogue its in. – zephyr Sep 2 '16 at 12:53
• FYI, I'm not sure if you know, but the general naming format for exoplanets is STAR_NAME X where X is some lower-case letter starting at b for the closest planet to the star and proceeding alphabetically for every planet thereafter. An example would be HD 1160 b which is the closest planet around the star HD 1160 (the HD referencing the Henry Draper Catalogue). – zephyr Sep 2 '16 at 12:58
• @zephyr Yes I knew that. Though thanks ^.^ The exoplanet database looks nice – Durakken Sep 3 '16 at 4:33

Best chance would be the Hipparcos catalogue. The first set of Gaia data will be released Mid-September 2016, but I don't know if it will be more accurate than Hipparcos already.

All stars within 11,462 light years of Earth.

That won't be easy. These catalogues have a magnitude (brightness) cutoff. Brighter, more massive stars can be seen further away than smaller, darker ones.

Their stellar classification.

Spectral type should be in there.

If they have any planets around them (hypothetical or otherwise)

Searching for Exoplanets is an ongoing project, and there is no complete catalogue in any sense of the word yet for any radius. Most Exoplanets were found with the Kepler mission, but that one looked in a fairly small part of the sky. What exactly do you mean by hypothetical planets?

Their position using an x, y, z coordinate relative to earth or galaxy center (I don't really get declination, etc)

You'll have to convert that yourself. If you know how to program, there are libraries for coordinate conversion. I would argue, though, that an Earth-centred spherical coordinate system is preferential for most applications.

Distances are hard to measure. Hipparcos and Gaia use the parallax method. This gets less accurate with increasing distance. Also, distances are naturally measured in parsec, but the conversion to light years is trivial.

The Gaia catalogue will have $10^9$ stars with positions and velocities. It will also be more accurate than Hipparcos. But the measurements are ongoing, and the final data release is planned for 2022.

• Isn't there a compendium/compilation catalog? That while one catalog might not have it another does so it's all included in 1 catalog or no? What I mean with the planets is that I'm going to have to generate the majority of those anyways, but if there are possible planets there if it's noted I'd find it useful to have it there to see what it's saying a star has. As to the coordinate system... it doesn't hurt to ask ^.^ I hate that system, but yeah I'm going to have to convert anyways, I was just hoping not to have to figure that out too. – Durakken Sep 2 '16 at 9:34
• As far as lightyear vs parsec that's fine... I consider both bleh measures outside of average human practical use ^.^ I have my own unit that is equivalent to 24 Terameters so technically if they measured in terameters that would be ideal for me ^.^ ---- Also is there a rough guess at how many stars are in that volume? I need to know that to know how many I need to generate, even with a catalog. – Durakken Sep 2 '16 at 9:37
• @Durakken: Well, length conversion is simple, and Parsec is what the actual measurement is, so that's what's used. As for a compendium catalogue of stars and planets, to my knowledge there isn't one. When the Hipparcos catalogue was made, there were no / very few exoplanets. Also, it's mostly used by people interested in stellar evolution and galactic dynamics, and these people don't need planets. Exoplanet researchers are better off with a specialized catalogue that doesn't consist of 99.x% irrelevant entries. Best chance is to find an exoplanet catalogue and match positions with Hipparcos. – Alex Sep 2 '16 at 9:53
• To find sunlike stars at that distance, abs mag 4.83, your catalog will need a cutoff of at least magnitude 17.6. A decent calculator: calctool.org/CALC/phys/astronomy/star_magnitude You might be able to find suns that far out in a catalog, if not hidden behind nebula, but you're going to have to just make up the distant K and M type star locations. – Wayfaring Stranger Sep 2 '16 at 13:28
• Well dl the HIP and Tycho Catalog... They're useless to me. i need the position data calculated out, not the arc seconds and such cuz I don't understand the math to get the position out of that... – Durakken Sep 3 '16 at 4:13