Introduction
Johannes Hevelius (1611–1687) was a Polish astronomer, born at Gdańsk in a wealthy family of brewers. As a young man, he visited several countries of Europe. Back in Gdańsk, he dedicated himself to business and public affairs. Starting in 1639, he turned most of his attention to astronomy under the advice of his former professor Peter Crüger, while remaining involved in the public affairs of the city until the end of his life.
Johannes Hevelius
He conducted his observations from an observatory built on the roof of his house, made his own telescopes, had a printing press in his house, and drew and engraved many of the plates used to illustrate his books. He suffered a major setback in 1679 when his house, observatory, and library were destroyed by fire, but he rebuilt and continued his work.
Hevelius discovered the libration of the moon, charted the moon's surface, observed sunspots, and discovered four comets. He published several astronomy books. His last work, Prodromus Astronomiæ [5], was published posthumously by his second wife and collaborator Elisabeth Koopman in 1690. It contains a star catalog of 1564 entries entitled Catalogus Stellarum Fixarum (pp. 143–268) and a celestial atlas Firmamentum Sobiescianum. The atlas features 10 new constellations, described in the next section.
The telescope was in its infancy at the time, but Hevelius preferred to conduct his measurements of star positions with plain sights. This triggered a controversy with Robert Hooke, secretary of the Royal Society of which Hevelius was a fellow, who dispatched Edmond Halley to Gdańsk in 1679. Halley validated Hevelius's methods.
More biographical details can be found in Baily [3] in the introduction to Hevelius's catalog. This page focuses on the star catalog from Prodromus. This catalog came after Tycho Brahe's and attempted to improve on it, but was overshadowed by Flamsteed's only a few decades later. Still, it contains many stars not included in Flamsteed's catalog and has regularly been referred to by later astronomers.
Hevelius's catalog has already been put in machine-readable form by F. Verbunt and R. H. van Gent [1] and made available as VizieR's catalog J/A+A/516/A29.
I digitized it independently anyway in order to capture the original catalog's columns omitted in VizieR, which contain the stars' equatorial coordinates computed from the ecliptic ones, as well as the ecliptic coordinates according to the catalogs of Tycho Brahe, William IV Landgrave of Hesse-Cassel, Giovanni Battista Riccioli, Ulugh Beg and Ptolemy, precessed to Hevelius's catalog equinox (1661).
I also included Baily's reprint of Hevelius's catalog in [3] and Flamsteed's version in Historia Cœlestis [4]. Flamsteed's version has been the one in most general use, but it orders the stars differently and I wanted to capture the mapping between versions.
Constellations in Hevelius's catalog
Hevelius's catalog groups stars by constellation. Only 43 of the 48 Ptolemaic constellations are represented: the southernmost (Ara, Centaurus, Corona Australis, Lupus, and Piscis Austrinus) are omitted. Only the northern parts of Eridanus and Navis are populated.
Hevelius includes the newer constellations Antinous and Coma Berenices introduced by Caspar Vopel in 1536 and already adopted by Tycho Brahe in his catalog. He also includes the constellations Camelopardalis and Monoceros introduced by Petrus Plancius on a globe in 1612.
In addition, the catalog and atlas feature 9 new constellations:
| Hevelius's Name | Modern Name |
|---|---|
| Canes Venatici, Asterion & Chara | Canes Venatici |
| Cerberus | |
| Lacerta sive Stellio | Lacerta |
| Leo Minor | Leo Minor |
| Lynx sive Tigris | Lynx |
| Scutum Sobiescianum | Scutum |
| Sextans Uraniæ | Sextans |
| Triangulum Minus | |
| Vulpecula cum Ansere | Vulpecula |
of which two are now obsolete (Cerberus and Triangulum Minus, reabsorbed into Hercules and Triangulum) but the other seven have remained in use and are now part of the official 88. The atlas also features the obsolete constellation Mons Menalis at the foot of Boötes.
In the catalog, the constellations are generally enumerated in alphabetical order of their Latin names, considering the letters U and V as identical (the Ursæ come after Virgo). Camelopardalis is a little out of place, which Baily has corrected. Canes Venatici appears after Canis Major and Canis Minor as if the plural "Canes" were considered equivalent to "Canis" in the alphabetical order.
Catalog data
The following files cover the different versions of the catalog.
| File name | Explanation |
|---|---|
| ReadMe | File descriptions |
| hevelius.dat | Hevelius's full catalog according to Prodromus |
| hevelius_h.dat | Hevelius's simplified catalog according to Prodromus |
| hevelius_b.dat | Hevelius's catalog according to Baily |
| hevelius_z.dat | Hevelius's catalog according to Flamsteed |
| notes.dat | Notes on Hevelius's catalog |
| notes_b.dat | Notes on Baily's version of Hevelius's catalog |
| notes_z.dat | Notes on Flamsteed's version of Hevelius's catalog |
| notes_eq.dat | Notes on equatorial coordinates |
The ReadMe file describes the file formats, following the conventions for catalog descriptions of the VizieR service.
The file hevelius.dat contains the full Hevelius catalog. The original uses two lines to represent each catalog entry. The first line contains the description, Tycho number and magnitude, Hevelius magnitude, longitudes, and right ascension; the second line the latitudes and declination. The file presents each entry on a single "unfolded" line for convenience.
The files hevelius_h.dat, hevelius_b.dat, and hevelius_z.dat contain the catalog versions according to Hevelius (a selection of columns from hevelius.dat), Baily, and Flamsteed. For easy comparison, their layouts are compatible, although Flamsteed uses polar distance rather than declination and the magnitude representations differ. The ecliptic coordinates precede the equatorial ones in the files, although they follow them in the original Flamsteed version.
Hevelius's numbering occupies the first three columns. The next three columns give Baily's numbering in Baily's version, when it differs from Hevelius's, and Flamsteed's numbering in Flamsteed's version.
The notes files collect observations about the respective versions such as the particular format of magnitude values, typos and errors that I detected, discrepancies between versions, etc.
There are several computation errors in Hevelius's equatorial coordinates, some of which were fixed by Baily or Flamsteed. I have recomputed all equatorial coordinates (with the unfair assistance of an electronic computer) and compared them with Hevelius's values in notes_eq.dat. I used the value 23°30'20" for the obliquity of the ecliptic, according to Baily [3, p. 47].
Flamsteed's version
Hevelius's catalog in reprinted in John Flamsteed's Historia Cœlestis Britannica [4], but in a different form. Flamsteed reordered the constellations and, within each constellation, reordered the stars by right ascension, west to east (with 3 exceptions documented in notes_z.dat).
Flamsteed's version merges the constellations Triangulum Minus and Triangulum into Triangula (the Triangles). It omits the 18 catalog entries for which Hevelius has not given coordinates of his own, as well as 2 duplicate entries in Perseus (Per 47 and Per 48) that would be conspicuous in a list sorted by constellation and right ascension. For no apparent reason, the constellations Corvus (8 stars) and Leo Minor (18 stars) are omitted entirely, and so is a single star in Sextans (Sex 4). Flamsteed's version ends up with 1517 catalog entries instead of 1546, to which I have assigned a global sequence number and a sequence number within the constellation.
As Baily mentions [3, p. 47], references to Hevelius's catalog found in the work of later astronomers usually use Flamsteed's numbering. The file hevelius_z.dat includes the mapping between Hevelius's and Flamsteed's numberings.
Baily's version
Baily mentions and numbers the entries without Hevelius coordinates, but leaves the coordinates blank.
He rectifies the alphabetical order of the constellation names by placing Camelopardalis before Cancer. This only affects the global numbering of the stars from Camelopardalis to Canes Venatici.
He corrects the equatorial coordinates which he had "reason to suspect" [3, p. 47]. The file notes_eq.dat flags the ones he or Flamsteed caught.
Star identifications
Baily assigns Bayer, Flamsteed, or Piazzi designations to Hevelius's stars, and sometimes a reference to Lalande's Histoire Céleste Française (which I tried to resolve, not always successfully, using Baily's edition [2]). Flamsteed only identifies the stars for which a letter exists, from Bayer's atlas or Flamsteed's own catalog. Vizier catalog J/A+A/516/A29 uses references to the Hipparcos catalog.
I translated these identifications to the same format (defined in ReadMe) in the following files, and gathered the ones I retained for the maps in ident_o.dat.
| File name | Explanation |
|---|---|
| ident_b.dat | Star identifications according to Baily [3] |
| ident_z.dat | Star identifications according Flamsteed [4] |
| ident_a.dat | Star identifications according VizierR catalog J/A+A/516/A29 |
| ident_o.dat | Star identifications retained for the maps |
| dups_o.dat | Duplicate entries |
| tyccmp_oo.dat | Notes about Tycho numbers in Hevelius's catalog |
Duplicate entries
The file dups_o.dat lists the 13 pairs of duplicate entries found in the catalog, with the indication whether the members of each pair have identical or just very close positions. The maps show double labels for all pairs.
The list is based on the identifications in ident_o.dat but it is identical to the list of duplicates in Verbunt & van Gent [1]. Baily flags only 4 pairs of duplicates in his notes (see notes_b.dat) but his identifications are compatible with the full list of 13. Flamsteed omits two duplicate entries in Perseus but fails to catch any other legitimate pair of duplicates through his identifications.
Tycho numbers
The catalog gives Tycho numbers for many entries, in addition to precessed Tycho positions. I compared this mapping to Tycho's catalog with the one obtained by comparing the identifications of Hevelius's stars in ident_o.dat and the corresponding identifications file for Tycho's catalog.
The file tyccmp_oo.dat lists the discrepancies between these mappings, with a brief explanation. Some of these discrepancies are due to Tycho's number referring to another constellation. They are collected in the following list.
| Hevelius | Tycho | |||
|---|---|---|---|---|
| 258 | Cnc | 2 | Hya | 24 |
| 273 | Cnc | 17 | CMi | 5 |
| 993 | Mon | 1 | Ori | 58 |
| 994 | Mon | 2 | Ori | 60 |
| 995 | Mon | 3 | Ori | 57 |
| 996 | Mon | 4 | Ori | 56 |
| 997 | Mon | 5 | Ori | 59 |
| 998 | Mon | 6 | Ori | 61 |
| 999 | Mon | 7 | Ori | 62 |
| 1000 | Mon | 8 | Ori | 53 |
| 1001 | Mon | 9 | Ori | 55 |
| 1002 | Mon | 10 | Ori | 54 |
| 1202 | Psc | 38 | And | 12 |
| 1241 | Sco | 7 | Lib | 17 |
| 1242 | Sco | 8 | Lib | 16 |
| 1243 | Sco | 9 | Lib | 12 |
| 1314 | Ser | 9 | Oph | 16 |
| 1317 | Ser | 12 | Oph | 17 |
| 1318 | Ser | 13 | Oph | 35 |
| 1319 | Ser | 14 | Oph | 36 |
| 1320 | Ser | 15 | Oph | 9 |
Other discrepancies are due to Tycho's number referring to Kepler's Secunda Classis catalog. They are collected in the list below, which agrees with the one given in Verbunt & van Gent [1] (caveat: my numbering of Kepler's Secunda Classis stars, still unpublished, differs from Hevelius's in Sagittarius due to the different treatment of the multiple copies of γ2 Sgr and δ Sgr).
| Hevelius | Kepler | |||
|---|---|---|---|---|
| 296 | CMa | 11 | CMa | 14 |
| 298 | CMa | 13 | CMa | 16 |
| 299 | CMa | 14 | CMa | 17 |
| 302 | CMa | 17 | CMa | 18 |
| 716 | Eri | 18 | Eri | 23 |
| 717 | Eri | 19 | Eri | 24 |
| 718 | Eri | 20 | Eri | 25 |
| 719 | Eri | 21 | Eri | 26 |
| 720 | Eri | 22 | Eri | 27 |
| 721 | Eri | 23 | Eri | 28 |
| 722 | Eri | 24 | Eri | 29 |
| 723 | Eri | 25 | Eri | 30 |
| 724 | Eri | 26 | Eri | 31 |
| 725 | Eri | 27 | Eri | 32 |
| 726 | Eri | 28 | Eri | 33 |
| 834 | Hya | 24 | Hya | 31 |
| 1218 | Sgr | 10 | Sgr | 15 |
| 1219 | Sgr | 11 | Sgr | 20 |
| 1220 | Sgr | 12 | Sgr | 19 |
| 1221 | Sgr | 13 | Sgr | 18 |
| 1229 | Sgr | 21 | Sgr | 26 |
| 1230 | Sgr | 22 | Sgr | 27 |
| 1231 | Sgr | 23 | Sgr | 28 |
| 1232 | Sgr | 24 | Sgr | 29 |
| 1275 | Oph | 14 | Oph | 44 |
| 1276 | Oph | 15 | Oph | 45 |
| 1277 | Oph | 16 | Oph | 46 |
| 1278 | Oph | 17 | Oph | 47 |
Accuracy of the catalog
The file dists_o.dat gives the differences between Hevelius's positions and the modern positions of the corresponding stars (according to ident_o.dat) from the Hipparcos catalog (or the SAO or HD catalog if there is no Hipparcos match) adjusted to Hevelius's epoch and equinox. Its file format is described in ReadMe.
| File name | Explanation |
|---|---|
| dists_o.dat | Differences between Hevelius's positions and modern ones |
The file gives the differences in ecliptic longitude (multiplied by the cosine of the latitude for normalization), the differences in ecliptic latitude, and the great circle distances, all in minutes of arc. The corresponding histograms below give a general idea of the overall accuracy of the catalog (data outside the range of the x axis has been discarded).
| Longitude | Latitude | Distance |
|---|---|---|
 |
 |
 |
At first sight, the numbers suggest a 10% improvement over Tycho's positions in Hevelius's catalog. Verbunt & van Gent [1] includes a much finer analysis.
References
[1] F. Verbunt & R. H. van Gent, The star catalogue of Hevelius, Astronomy & Astrophysics 516, A29 (2010).
[2] Jérôme de Lalande, A Catalogue of Those Stars in the Histoire Céleste Française of Jérôme Delalande, for which tables of reduction to the epoch 1800 have been published by Professor Schumacher reduced at the expense of the British Association for the Advancement of Science, under the immediate superintendence of the late Francis Baily, Esq.. London: Richard & John E. Taylor, 1847.
[3] Francis Baily, The Catalogues of Ptolemy, Ulugh Beigh, Tycho Brahe, Halley, Hevelius, Deduced from the Best Authorities. With Various Notes and Corrections, and a Preface to Each Catalogue. To Which is Added the Synonym of each Star, in the Catalogues of Flamsteed or Lacaille, as far as the same can be ascertained. Memoirs of the Royal Astronomical Society, Vol. 13, London, 1843. Also available here.
[4] John Flamsteed, Historia Cœlestis Britannica, Tribus Voluminus contenta. Volumen Tertium, London, 1725.
[5] Johannes Hevelius, Prodromus Astronomiæ, Gdańsk: Johann Zacharias Stoll, 1690.