Description
This page describes the construction of the star set represented on the reference star maps, the historical catalogs maps, and used to populate the identifications files for the historical catalogs.
Basic star set
I used the Yale Bright Star Catalogue (novae and non-star objects excepted) as a starting point. I augmented this set with the stars present in Flamsteed's star catalog but too faint to appear in the Bright Star Catalogue, and the few variable stars mentioned in Delporte's Atlas Céleste [2] but absent from the Bright Star Catalogue (their data taken from the General Catalogue of Variable Stars).
Then, using the book Lost Stars [1] by Morton Wagman as primary reference, I have attempted to restore all the original Bayer/Lacaille and Flamsteed designations to these stars, including Bayer's Latin letters, even capital A's. Due to the long history of these designations and the number of astronomers involved, there are many uncertain cases. I have erred on the side of caution, following the detailed explanations from Wagman and using the SIMBAD service as a last resort.
All the stars in the set have an entry in the Henry Draper Catalogue (HD). The HD numbers were used to find matching entries in the Hipparcos Catalogue where the star positions and magnitudes come from. The positions were adjusted for the epoch J2000.0 according to proper motion and precessed to the J2000.0 equatorial coordinate system. A few stars have no entry in Hipparcos but could be found in the SAO catalog (either by HD number or the SAO number provided by the Bright Star Catalogue).
I have also included official star names taken from the IAU Catalog of Star Names (version 2018-09-07).
Complete star set
In the case of double and multiple stars, it is sometimes unclear which fainter components should be covered by a given catalog designation. To address this situation, I collected for each reference star all the entries in the HR, HD, HIP and SAO catalogs whose position is close (5 minutes of arc or less by default) to the reference star's. The result is contained in ident_raw.dat.
Then, for each reference star, I combined the catalog designations of these matches into a single entry in ident.dat. Most cases were straightforward, all the matches clearly representing the same star, but there are quite a few cases where it was not obvious which matches should be retained as components of the reference star. The difficult cases are documented in notes_id.dat.
| File name | Explanation |
|---|---|
| ReadMe | File descriptions |
| star_ids.dat | Combined designations: Bayer/Lacaille, Flamsteed, HR, HD, HIP, SAO. |
| star_pos.dat | Star positions (J2000.0) and magnitudes from HIP or SAO. |
| ident_raw.dat | Raw matches by distance from HR, HD, HIP, SAO. |
| ident.dat | Combined designations derived from ident_raw.dat. |
| notes_id.dat | Notes on the construction of ident.dat and special cases |
| ref_ident.pdf | Visual representation of cross-references |
The complete list star_ids.dat results from joining the basic star set (which has updated Bayer/Lacaille and Flamsteed designations), with ident.dat (which has HR, HD, HIP and SAO designations for the components). The file star_pos.dat gives the star positions and magnitudes from the Hipparcos or SAO catalog. For multiple stars, the positions are computed as averages of the components' positions weighted by their flux density ratios.
The last section in notes_id.dat lists the cases where more than one match has been retained in at least one of the reference catalogs. For each one of these, the file ref_ident.pdf gives a rough graphical representation of the cross-references provided by the catalogs. The leftmost column contains the reference star's key (main HD number). The other four columns respectively contain the HR, HD, HIP and SAO designations, including component letters. Additional information about component letters and cross references for Hipparcos stars was obtained from the Catalog of Components of Double & Multiple stars (CCDM).
- A line HR—HD represents the HD assignment found in HR.
- An arrow HD→SAO represents the SAO assignment found in HR.
- An arrow SAO→HD represents an HD assignment found in SAO.
- A solid line HIP—HD or HIP—SAO represents an assignment found in HIP.
- A dotted line HIP—HD or HIP—SAO represents an additional assigment found in CCDM.
- A component letter on a line from HIP—HD or HIP—SAO comes from HIP or CCDM.
The catalogs are in agreement in many cases, but there are also many situations where they show inconsistencies. At least, I have documented the construction of star_ids.dat and any controversial case can be readily tracked down to the sources.
References
[1] Morton Wagman, Lost Stars, McDonald & Woodward Publishing Company, Blacksburg, Virginia, 2003.
[2] Eugène Delporte, Atlas Céleste, Cambridge University Press, 1930.