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The sample most commonly in use today is the Catalog of Nearby Stars, Third Edition (preliminary) by Wilhelm Gliese and Harmut Jahreiß (1991) (hereafter CNS3p). It is the source of the Gl and GJ prefixes attached to many nearby stars. It was not the first such list, but it has been the most successful, starting with the first edition of 915 systems within 20 pc in 1957, eventually expanded over the years to 22 pc (Gliese 1969) and then 25 pc (Gliese & Jahreiß 1991), with additional contributions out to 25 pc by Woolley et al. (1970). The 1991 preliminary catalog included 3803 entries for objects, 1388 of them unnamed by Gliese, Jahreiß or Weilen. Later, the Centre de Donnes in Strasbourg invented GJ numbers exceeding 30001_{. Thanks to the ubiquity of the SIMBAD and VizieR databases, these}

1_{Gliese names are notoriously baroque, which probably comes with 40 years of evolution. Unfortunately,}

have become de-facto standard ways to refer to these stars. For their parts, Gliese and Jahreiß recommended using other names- generally Luyten’s. As Gliese died in 1993 and the available data changed considerably (the release of YPC in 1995 and the HIPPARCOS

results in 1997), a final version of the Third Edition has never been published. There is, however, an online version of CNS hosted by the Astronomisches Rechen-Institut Heidelberg (ARI), which I refer to as ARICNS2_.

The Catalog of Nearby Stars, in all versions, included stars with photometric and spec- troscopic distance estimates, as well as a variety of parallax errors (with some judicious care; Gliese (1969) notes that he excluded several known members of the Pleiades whose low quality mean parallaxes erroneously put them within 22 pc). With the exception of the occasional astrometric or spectroscopic binary, The Catalog of Nearby Stars is a one- object-per-line table, with systems identified by Gliese name and component ID. Systems

The 1957 catalog lists 915 systems in increasing B1950 right ascension order, with A and B designating components. In the 1969 second edition, Gliese used decimal points to insert more systems (Gl 87.1AB are between Gl 87 and Gl 88 in B1950 right ascension, and unrelated to either). The new systems in the 1979 update have GJ prefixes and restart their numbering at 1001 (stars with reliable parallaxes) or 2000 (stars without reliable parallaxes). “GJ” has largely supplanted “Gl” for all CNS stars.

1,388 entries in CNS3p are marked NN (no name); by 1997, common usage (and CDS Strasbourg) settled on renumbering all the new stars by line - all GJ 3000+ names are artificial, and each refers to astar, not a system. Note that the original system did not work out so well: famous multiples with different names include Gl 49/51; Gl 264/Gl 264.1AB; Gl 559AB/Gl 551=αCen AB and Proxima; Gl 643/644ABCD; Gl 799AB/803=AU Mic/AT Mic; Gl 879/881=Fomalhaut and TW PsA.

2_{Jahreiß & Weilen, http://www.ari.uni-heidelberg.de/datenbanken/aricns/ checked 2012 JUL 15.}

Jahreiß claims (in the 2001 NStars workshop) the final CNS3 was released in 1991, and CNS4 was re- leased in 1997 with 3134 components to 2679 systems; ARICNS seems to have over 5800 entries and is therefore probably CNS4+working sample. This is borne out by the difficulty of using it: ARICNS exists as 5800 separate HTML files accessible by a set of index pages that divide the stars up in different ways, and some relevant information like Giclas and Ross names only exist on their respective index pages. ARICNS also introducesfivenew prefixes, all going by system and starting over from 1 each time: N1 (2055 systems), N2 (111 systems), NV (215 systems), N3 (10 systems), and NH (215 systems). N1 contains all 1388 no-name stars from CNS3p and may have been the final CNS3 additions; it’s not clear what the rest are, and all of the stellar samples named via the new prefixes contain large numbers of stars not even remotely close to being within 25 pc.

are included based on a trigonometric parallax, photometric parallax, and/or spectroscopic parallax larger than 39 mas (25.6 pc) to increase the likelihood that all stars within 25 pc (40 mas) have been included. There is also one entry for the Sun, which contains an apparent and absoluteV magnitude and a few colors.

CNS3p contains B1950 positions, two parallaxes (the trigonometric parallax where avail- able, and the catalog’s adopted parallax, which is always the trigonometric parallax when the error is less than 14%, otherwise a photometric or spectroscopic one), proper motions and position angles, radial velocities, spectral types (a mix of MK system, original HD catalog classifications, and estimates by Luyten),V magnitudes and an assortment of colors (B₋V, U₋B,R₋I) on the Johnson-Kron system, computed UVW space velocities (with U toward the Galactic center), an assortment of names (HD, Durchmustrung, Giclas, LHS, other) and brief remarks. ARICNS additionally contains positions in J2000 E2000 and B1900 E1900 epochs and equinoxes, proper motion broken into RA and DEC, and HIPPARCOS data in the form of names and unformatted table entries from Perryman et al. (1997).

Only the parallaxes are quoted with errors, though most important data are accompa- nied by a remarks column that pertains to quality or, occasionally, source; the photometry column also contains a specification for joint magnitudes. There are no references to source publications for any of the data except as may be included in the remarks. Information about multiple systems is relegated to the remarks as well; generally the separation and position angle (or orbital period) is given in the B component’s note, while the alternate name and delta magnitude is given in A component’s note.