Star Catalogue Database

[Debra Necochea]

The HYG database (v3.7) and Augmented Tycho-HYG (v2.4) catalogs are compilations of interesting (to me, anyway) stellar data from a variety of catalogs. They are useful for background information on all sorts of data: star names, positions, brightnesses, distances, and spectrum information. A version of the HYG catalog also powers the charts elsewhere on this site.

This is the entire AT-HYG catalog. All Tycho-2 stars with a valid magnitude are included, along with data from Gaia DR3 for distances, proper motions, and radial velocities for most stars. Data from HYG is used when available and relevant (such as proper names, Bayer + Flamsteed IDs, and the catalog IDs for stars used to create the HYG catalog.)

The full catalog is quite large (2.5M stars). For smaller applications, several subsets of the full catalog are available. One of these, the HYGLike subset, has the same schema as the original HYG database, but updates many of the HYG stars with Gaia DR3 or DR2 data (whatever was found during the build of AT-HYG). It is intended to be a drop-in or near-drop-in replacement for HYG for many applications. The other two subsets are field-for-field identical with the full AT-HYG catalog; there are just fewer stars than in the full catalog.

The database is a comma separated values (CSV) file that can be imported into most database and spreadsheet programs. On this web site it is stored as a Zip file or a GZ file, which most popular unzippers can open.

The primary goal was to take advantage of the spectacular data sets from Gaia, especially the Data Releases 2 and 3 (DR2 + DR3), which contained over 1 billion exceptionally precise distance measurements to stars throughout our galaxy. I also wanted something larger than the older HYG catalog, since I first developed it over 15 years ago, when limits on computer storage and processing ability were more significant.

The Tycho-2 catalog was a suitable happy medium: at 2.5 million stars, it has more than enough for typical charting applications, and more than 20 times as many as HYG, but the data set is still manageable by fairly small applications in the 2020s. Combining the Tycho-2 catalog with distance and velocity information from Gaia DR3, along with suitable cross-reference IDs to other catalogs (principally HIPPARCOS and Henry Draper) gives the Augmented Tycho or AT catalog.

Combining AT with the HYG dataset gives all the additional data collected for HYG, such as Yale Bright Star Catalog and Gliese IDs, common names (such as "Rigel" or "Polaris"), and additional information especially useful to amateur astronomers. This combined dataset is the AT-HYG catalog.

AT-HYG has now been updated to Version 2.4. The 2.x versions add significant numbers of new fields. Version 2.0 is the biggest change from 1.x, with Gaia DR3 proper motions and radial velocities for approximately 75% of all stars plus Gaia DR3 proper motions only (no RVs) for most of the remaining 25%. Later versions add a few more fields of interest, listed below, and fix a few cases of missing or doubtful data in specific fields. For more details on updates to versions, see the version history.

The HYGLike subset of AT-HYG is designed to behave like HYG. The field names are the ones from HYG rather than AT-HYG. The only new fields are the `*_src` fields from AT-HYG, which are included in the HYGLike subset so that the sources of the various fields are clear. For example, in the original HYG, distances could safely be assumed to be from HIPPARCOS in the vast majority of cases, but in AT-HYG they are mostly from Gaia DR3, with some from Gaia DR2 and a few from HIPPARCOS when Gaia data was not available.

There are a few differences in the contents of the fields in HYGLike vs. HYG, mostly having to do with some data that was present in HYG but not in AT-HYG. If your application doesn't use any of these fields, HYGLike is a drop-in replacement for HYG. Otherwise, you may need to make some small changes:

Currently, versions v3.1 through v3.6 are only available at the Github repo. I have retained version 3.0 on this site because it was the most current version for over 8 years, and it may make sense for some older applications, but new applications should use v3.7 (or later, if applicable).

I came up with this database while creating the 3D Universe web site. I needed a reference that would let me search for groups of stars by magnitude or distance, while giving me more information than was contained in any one catalog.

I started with the Hipparcos data. The Hipparcos data set represents by far the most comprehensive collection of stellar distance and brightness data in existence, except for very low-luminosity stars. Essentially all naked-eye stars (in fact, most stars down to about apparent magnitude +9 and many others down to about +11) are represented in the Hipparcos catalog.

I next consulted the Gliese catalog to fill in gaps in the Hipparcos catalog, and to add various Gliese data to the catalog. In particular, the Gliese catalog ID is a common reference for nearby stars, and the Gliese catalog contains radial velocity data, which Hipparcos lacks. Additionally, though Hipparcos distances are generally superior to Gliese data, the Hipparcos catalog missed many nearby stars that were below its magnitude cutoff.

To cross-reference stars, I used the Henry Draper catalog number, whenever present, to add Gliese data to the Hipparcos catalog. Many of the faintest stars lacked this catalog number, so I compared the positions and brightnesses of Gliese stars to those in Hipparcos, and if they matched to within a certain tolerance, I assigned the appropriate Gliese data to the Hipparcos star. Stars that failed both references were then added to the end of the Hipparcos list.

I also converted Hipparcos apparent magnitudes to Gliese values for all components of known multiple stars in the latter catalog. Again, the Hipparcos magnitude measurements are often superior, but the Hipparcos catalog treats multiple stars inconsistently. In particular, it breaks some out as separate stars (e.g., Alpha Centauri) but merges others (such as Capella, 70 Ophiuchi, and many others). By contrast the Gliese catalog breaks all known multiple stars, excluding those too close to be separated optically, into their components, and gives each one a magnitude.

I then calculated absolute magnitudes for all stars, added those to the database, and added about 250 proper names. Then, again using Henry Draper as a cross reference, I added data from the Yale Bright Star Catalog: HR numbers, radial velocities (if not already added from Gliese), and the Bayer and Flamsteed designations. Finally, I added a number of radial velocities from the Wilson Evans Batten catalogue to stars that didn't already have that information.

In short, though I have done what I can, I can't warrant the database to be error-proof. If you need to launch probes to all the stars in the database, you might want to give it a more thorough going-over before doing so :-)

This tool searches the standard star catalogues for standards that are within dX airmasses of the target at a given LST. To search the catalogues, enter target coordinates and LST of target observation (Target LST).

You may want to observe the standard star at a different LST than when the target was observed. In this case put the LST when the target was observed in the TargetLST box as before, and put the LST of the standard star observation in the StdObs LST box.

The spectral type range fields may be left blank in which case all types will be searched. The magnitude range fields can be used to specify lower and upper limits for a selectable magnitude. Using the default range values will include all objects regard less if they have a measured magnitude or not.

Coordinates and sidereal times can be entered using : or as seperators. Seconds need not be entered, ie. 4:32 will be interpreted as 04:32:00.
If required, it is possible to make and alternative search for specific sub-strings of the target ID. In this case just fill in the lower right box and hit SEARCH NAME.

A star catalogue is an astronomical catalogue that lists stars. In astronomy, many stars are referred to simply by catalogue numbers. There are a great many different star catalogues which have been produced for different purposes over the years, and this article covers only some of the more frequently quoted ones. Star catalogues were compiled by many different ancient people, including the Babylonians, Greeks, Chinese, Persians, and Arabs. They were sometimes accompanied by a star chart for illustration. Most modern catalogues are available in electronic format and can be freely downloaded from space agencies' data centres. The largest is being compiled from the spacecraft Gaia and thus far has over a billion stars.

From their existing records, it is known that the ancient Egyptians recorded the names of only a few identifiable constellations and a list of thirty-six decans that were used as a star clock.[1] The Egyptians called the circumpolar star "the star that cannot perish" and, although they made no known formal star catalogues, they nonetheless created extensive star charts of the night sky which adorn the coffins and ceilings of tomb chambers.[2]

In Ancient Greece, the astronomer and mathematician Eudoxus laid down a full set of the classical constellations around 370 BC.[7] His catalogue Phaenomena, rewritten by Aratus of Soli between 275 and 250 BC as a didactic poem, became one of the most consulted astronomical texts in antiquity and beyond.[7] It contained descriptions of the positions of the stars and the shapes of the constellations, and provided information on their relative times of rising and setting.[7]

The ancient Vedic and other scriptures of India were very well aware of the astronomical positions and constellations. Both Mahabharata and Ramayana provide references to various events in terms of the planetary positions and constellations of that time. The Planetary positions at the time of Mahabharata war has been given comprehensively. A very interesting and exhaustive discussion about the planetary positions along with specific name of constellations appears in a paper by R N Iyengar in the Indian Journal of History of Science.[15]

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