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Need help with the NStars Database?If you have questions concerning the NStars Database, and can not find the answer below, please visit the NStars Forum.NAMES IN THE NSTARS DATABASEGJ NAMES: The GJ (formerly Gl) names are from the Catalogue of Nearby Stars (CNS) series, also known as the Gliese Catalogues: Gli69 (CNS69, Gliese 1969), Gli79 (CNS79, Gliese and Jahreiss 1979), Gli91 (CNS91, Gliese and Jahreiss 1991). Because these are the benchmark compilatory catalogs used by researchers for decades, rather than research results, names for all (true) components mentioned in the entries or notes of the three editions are included by letter, i.e. A, B, C, etc. If it is not mentioned in the three CNS editions, then it is not given a Gl/GJ name, even if authors might assign it one in publication. GJ COMPANIONS: Companions in the CNS editions with separate photometry are included. However, stars indicated to be "SB", "SB?", or "VAR" were only listed to have companions if they had (1) orbital elements listed, or (2) semi-amplitude(s) listed, or (3) could be confirmed via an independent source. Astrometric companions were only included if they could be confirmed via an independent source. Common proper motion companions were confirmed/refuted by examining Digitized Sky Survey plates from two epochs. AS OF JUL 2001: CNS69 NOTES CHECKED. LUYTEN NAMES: The LHS names are straightforward, taken from Luy79 (the LHS Catalogue, LHS). In the few cases of small letters "a" or "b" these are actually part of the LHS name and have been included. No component designations such as "A" and "B" are used because they were not used by Luyten. LUYTEN COMPANIONS: Companions were searched for in the notes of Luy79. In some cases, they were confirmed/refuted by examining Digitized Sky Survey plates from two epochs. AS OF JUL 2001: ALL NOTES IN LUY79 CHECKED. GICLAS NAMES: The name selected is that with the lowest number, because that is the first report of the object. No component designations such as "A" and "B" are used because they were not used by Giclas. GICLAS COMPANIONS: Companions were searched for in Giclas publications by reading through the notes in the many Lowell Observatory Bulletins. In some cases, they were confirmed/refuted by examining Digitized Sky Survey plates from two epochs.
YPC, HIP, DM, HD, FLAMSTEED, BAYER (GREEK), HR NAMES: In these cases no component designations are given. It is generally the case that by searching a catalog one can find all components using the name given, so the additional letters are superfluous. In addition, it is not entirely clear in which cases the object was actually detected during the method of catalog generation, or it was merely listed because of prior knowledge. If companionship could not be confirmed, as is the case for many "B" component HIP stars with large parallaxes and errors that lie close to brighter stars, the various "B" names were removed because the companion is likely not a companion. DM NAMES: The order of acceptance for nomenclature is (1) BD, (2) CD, (3) CPD. Database Codes
PROCESS FOR DECONVOLVING CLOSE DOUBLES IN NSTARS DATABASE In general, if a multiple system is separated by less than 4" (and certainly if less than 1"), special care must be taken to divide up the flux from the individual components. The methodology used for entries in the NStars database uses a simple algorithm, as follows. Two pieces of data are required for the deconvolution in a closely separated system, where where "system" includes all components within the 4" spot on the sky: (1) the magnitude and error for the system must be available, and (2) the magnitude difference and error between the two sources (or more in some cases) must be available in the same bandpass (or reliably converted to the same bandpass). As an example, we look at the GJ1245 ABC system. Components AC comprise a close binary with a separation that varies from 0.4" to 1.2". Component B is about 6" distant. In this case, there will usually be two magnitudes for the system, one for AC and one for B. The magnitudes for B will be reported as separate and distinct. The magnitudes for AC must be deconvolved:
V (AC)
= 13.41 +/- 0.03 Weis
1996
V (A)
= 13.46 +/- 0.03 The deconvolved magnitudes will be posted in the NStars Database with an "*" that indicates an additional step has been made to derive the magnitude. The reference listed for both components will indicate where the magnitude difference and its methodology can be found. In cases where there is no reliable magnitude difference known, the magnitude will be listed for the primary only with the letter "J" for joint magnitude, and "decon" will be listed for the secondary because deconvolution is still pending.
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