Description
This page focuses on the identification of Halley's catalog entries. The corresponding page for Ptolemy's catalog explains in detail the general principles that I have followed for all catalogs regarding these identifications.
Identifications
The cross-references collected from Baily's version in cross_b.dat on the catalog page, as well as the ones provided by VizieR's catalog J/A+A/530/A93 (in the form of HIP numbers) have been resolved and/or expanded here in their respective ident_*.dat files.
| File name | Description |
|---|---|
| ReadMe | File descriptions |
| ident_b.dat | Identifications according to Baily's edition |
| ident_a.dat | Identifications according to VizieR J/A+A/530/A93 |
| ident_o.dat | Identifications retained for the maps etc. |
| ident_all.dat | All identifications combined in one file | notes_id.dat | Explanation of some identification choices in ident_o.dat |
The file ident_o.dat contains the identifications that I have retained for the maps, the computation of distances, and to establish cross-references to other catalogs. The file notes_id.dat comments on some of my choices. The file ident_all.dat combines all the identifications sets in one file for easy comparison.
Cross-references
The files below cross-reference Halley's catalog with other southern stars catalogs (De Houtman, Kepler, Lacaille) and with the reference star set, according to the identifications in ident_o.dat and similar identification files for the other catalogs (and found on their respective pages). They are described in ReadMe.
| File name | Explanation |
|---|---|
| halhou_oo.dat | Cross-references to De Houtman's catalog |
| halkep_oo.dat | Cross-references to Kepler's 2a and 3a classis catalogs |
| hallac_o.dat | Cross-references to Lacaille's Coelum Austrae catalog |
| halref_o.dat | Cross-references to the reference star set |
Explanations about the structure of these files can be found on the corresponding Ptolemy page.
Accuracy of the catalog
The file dists_o.dat, also described in ReadMe gives the differences between Halley's positions and modern positions of the corresponding stars (according to ident_o.dat) from the Hipparcos or the SAO catalog, adjusted to Halley's epoch and equinox. The corrections from corrs.dat mentioned on the catalog page have been applied before computing the distances.
| File name | Explanation |
|---|---|
| dists_o.dat | Differences between Halley's positions and modern ones |
The file gives differences in ecliptic longitude (multiplied by the cosine of the latitude for normalization), differences in ecliptic latitude, and great circle distances, all in arcminutes. 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).
| Longitude | Latitude | Distance |
|---|---|---|
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 |
 |
For a detailed analysis of the precision of Halley's catalog, refer to R. Verbunt & R. H. van Gent's article [1]. The peak of the distance histogram around 5 arcminutes suggests a precision not as good, but of the same order as Tycho Brahe's.
References
[1] F. Verbunt & R. H. van Gent, Early star catalogues of the southern sky, De Houtman, Kepler (second and third classes), and Halley, Astronomy & Astrophysics 530, A93 (2011).