sterner@warper.jhuapl.edu (Ray Sterner) (03/17/91)
Archive-name: astro/catalog/yale-bright-star/1991-03-15 Archive-directory: mandarin.mit.edu:/astro/data.etc/yale.bright/ [18.82.0.21] Original-posting-by: sterner@warper.jhuapl.edu (Ray Sterner) Original-subject: Re: Anyone know where the yale star catalogue may be FTP'd from ? Reposted-by: emv@msen.com (Edward Vielmetti, MSEN) loren@tristan.llnl.gov (Loren Petrich) writes: > On the subject of the Yale Bright Star Catalog, does anyone > know how complete it is advertised as? > The measure I would be interested in is a magnitude upper limit. > Is it complete to only magnitude 5.0, or 6.0, or 7.0? > And if there are several editions of it, what is the most > complete one, and where may it be found? >Loren Petrich, the Master Blaster: loren@sunlight.llnl.gov Here is a histogram of the visual magnitudes in the YBS (4th ed): Magnitude Number Range of stars -2.00 -1.50 0 -1.50 -1.00 1 Brightest star = -1.46 = Sirius -1.00 -0.50 1 -0.50 0.00 3 0.00 0.50 5 0.50 1.00 5 1.00 1.50 7 1.50 2.00 29 2.00 2.50 43 2.50 3.00 87 3.00 3.50 116 3.50 4.00 243 4.00 4.50 397 4.50 5.00 754 5.00 5.50 1299 5.50 6.00 2254 6.00 6.50 3286 6.50 7.00 524 7.00 7.50 36 7.50 8.00 6 Faintest star = 7.96 8.00 8.50 0 The YBS is obviously not complete to its faintest magnitude. It is certainly complete to some limit (0 -1.4 for instance) but that limit may not be very faint, I don't know what it is. It also contains 14 non-stellar objects which have their magnitudes set to exactly 0.0, none of the stars in the catalog have a magnitude of exactly 0, so this is an easy way to find the non-stellar objects (they have been removed from the above histogram). The YBS is a catalog of 9110 objects (9096 stars). It will never be complete to its faintest magnitude, but it includes many other values that are updated occasionally. Ray Sterner sterner%str.decnet@warper.jhuapl.edu Johns Hopkins University North latitude 39.16 degrees. Applied Physics Laboratory West longitude 76.90 degrees. Laurel, MD 20723-6099
stefano@harpo.phyast.pitt.edu (Stefano Casertano) (03/17/91)
Archive-name: astro/catalog/yale-bright-star/1991-03-15 Archive-directory: mandarin.mit.edu:/astro/data.etc/yale.bright/ [18.82.0.21] Original-posting-by: stefano@harpo.phyast.pitt.edu (Stefano Casertano) Original-subject: Re: Anyone know where the yale star catalogue may be FTP'd from ? Reposted-by: emv@msen.com (Edward Vielmetti, MSEN) In article <93191@lll-winken.LLNL.GOV> loren@tristan.llnl.gov (Loren Petrich) writes: > > On the subject of the Yale Bright Star Catalog, does anyone >know how complete it is advertised as? > > The measure I would be interested in is a magnitude upper >limit. > > Is it complete to only magnitude 5.0, or 6.0, or 7.0? > > And if there are several editions of it, what is the most >complete one, and where may it be found? > The Yale Bright Star Catalog, Fourth Edition (1982), is probably statistically complete to a visual apparent magnitude (V) of 6.0. The Supplement published in 1983 was supposed to bring the completeness limit to 6.5; in fact, the Catalog+Supplement is probably about only 80% complete between V=6.4 and 6.5, based on the number of stars. The Catalog+Supplement is probably statistically complete for V < 6.3. For your reference, the Supplement added only 5 stars with V < 6.0 to the 5085 listed in the Catalog, so it makes little difference whether or not the Supplement is used as long as you keep to V < 6.0. Note that completeness and magnitude limits depend rather sensitively on color. Part of the reason for the missed stars is that the original selection was based on photographic magnitudes, which correspond to somewhat bluer light and discriminate against very red stars. Reference: Bahcall, Casertano and Ratnatunga, Astrophysical Journal Vol. 320, pp. 515-526, September 1987. Stefano Casertano stefano@bondi.phyast.pitt.edu