Description
This page expands on the identification of Flamsteed's catalog entries presented on the catalog page in the file file flamsteed_ids.dat which collects the identifications in terms of HR and HD numbers according to Morton Wagman's book Lost Stars [1].
Identifications
The file ident.dat presented here provides magnitudes and additional modern designations for Flamsteed stars: Bayer letters and indices, HR, HD, HIP and SAO numbers. It also assigns secondary components to Flamsteed stars in more cases than flamsteed_ids.dat, as documented at the end of the file notes.dat on the catalog page.
| File name | Description |
|---|---|
| ReadMe | File descriptions |
| ident.dat | Identifications of Flamsteed's stars |
| dists.dat | Differences between Flamsteed's positions and modern ones |
| flmpto_o.dat | Cross-references to Ptolemy's catalog |
| flmtyc_o.dat | Cross-references to Tycho's catalog |
| flmhev_o.dat | Cross-references to Hevelius's catalog |
| flmref.dat | Cross-references to the reference star set |
Cross-references
The files flmpto_o.dat, flmtyc_o.dat, flmhev_o.dat cross-reference Flamsteed's catalog with those of Ptolemy, Tycho, Hevelius, and flmref.dat with the reference star set, according to the identifications in ident.dat and similar identification files for the other catalogs (and found on their respective pages). They are described in ReadMe.
Explanations about the structure of these files can be found on the corresponding Ptolemy page.
Accuracy of the catalog
The file dists.dat gives the differences between Flamsteed's positions, modified according Baily's corrections in flamsteed_pos.dat, and the modern positions of the corresponding stars (according to ident.dat) taken from the Hipparcos or SAO catalog, adjusted to Flamsteed's epoch and equinox.
The file gives the differences in right ascension (multiplied by the cosine of the declination for normalization), the differences in declination, and the great circle distances, all in minutes of arc. The corresponding histograms below give an idea of the overall accuracy of the catalog (data outside the range of the x axis has been discarded).
| Right Ascension | Declination | Distance |
|---|---|---|
 |
 |
 |
In Ptolemy's and Tycho's cases the standard deviations of the longitude and latitude differences have similar values. Here, the standard deviations of the RA and DE differences are quite different (~1.0 and ~0.4 respectively). The declination appears to be twice as accurate as the right ascension in Flamsteed's catalog.
The peak of the distance histogram occurs at about 0.6 arcmin, vs. 2 arcmin in Tycho's case. Using this as a measure of accuracy, we could say that Flamsteed's catalog is about 3 times more accurate than Tycho's.
References
[1] Morton Wagman, Lost Stars, McDonald & Woodward Publishing Company, Blacksburg, Virginia, 2003.