Overview The Yale Bright Star Catalog is an electronic catalog providing extensive stellar information for the brightest stars. It is large (megabytes), and includes extensive detail for each star (e.g. B-V color temperature, proper motion, catalogue names), much of which is not needed by charting software. It is normally distributed on magnetic tape, and has not (to my knowledge) been posted to the net. The highly reduced and hand-revised versions included with the "starchart" software family have appeared in two forms. The first (~160K, posted February, 1987) included merely location, magnitude and familiar names for a small number of stars. This recent reduction (~190K, posted October (?), 1987) adds spectral designation for potential color applications, double and variable star flags, Bayer and Flamsteed indices and increases the number of named stars. The current dataset was reduced directly from the original Yale data by Robert Tidd, using custom software. His file format is given below [1]. The raw output was hand-edited by Alan Paeth to remove a number of anomolies [2]. Users wishing to update or extend yale.star should look in part [3]. Disclaimer The original Yale Bright Star Catalog may not be used for commercial purposes without express previous written consent from the Department of Astronomy, Yale University. -- Part [1] File format for yale.star (reduced Yale star catalog, version 2) Name Col Len Type Desc ------------------------------------------------- ra 1 6 i6 ra 2000 hhmmss dec 7 5 +-i4 dec 2000 -mmss mag 12 3 {-}i magnitude*100 -dd or -ddd type 15 2 c2 object type type1 15 1 c1 object type 1 / star,ga,cl,neb,etc type2 16 1 c1 object type 2 / dbl,open,cl,etc spec2 17 2 c1d1 spectral 2 'G2' letter 19 2 c2 greek Bayer letter(s), or Flamsteed number const 21 3 c3 constellation (I.A.U. designation) name 24 30 c* name,descrip. newline 54 1 c1 newline (max final loc) $ -------- 'type1'/'type' 2 coding table CG-Glob.Cluster CO-Open Cluster GC-Galac.Cluster GP-Sphere Galaxy GS-Spiral Galaxy ND-Difuse Nebula NP-Planetary Nebula P*-Planet SS-star SB-Binary Star SD-Double Star SV-Variable Star VM-vector move VS-vector draw (solid) VD-vector draw (dotted) VH-vector draw (hyphens = dashed) I*-Invisible (for annotation) -------- 'letter' coding table # Flamsteed a-alpha b-beta g-gamma d-delta e-epsilon z-zeta h-eta @-theta i-iota k-kappa l-lambda m-mu n-nu E-xi o-omicron p-pi r-rho s-sigma t-tau u-upsilon 0-phi x-chi %-psi w-omega $-???? -------- Example: ---yale.star--- 141540+1911-11SSK2a BOOArcturus 062357-5241-72SSF0a CAR 051641+4600006SDG8a AURCapella . . . ---messier.star--- 053430+2202840ND TAUm1 Crab Nebula 175629-1901600CO SGRm23 202355+3832710CO CYGm29 ,good at low pwr 084026+1959370CO CNCm44 Praesepe, Beehive Cl . . . [2] Hand edits done on "raw" reduced yale.star [a] Proper names added: 062357-5241-72SSF0a CARCanopus 050229+4105000SSK5z AURCapella 195047+0852075SDA7a AQLAltair 173336-3706162SSB1l SCOShaula 125602+3819288SDB9a2CVNCor Caroli [b] Magnitude and Spectral data changes (based on "Norton"): 122636-6306158SDB1a1CRU 122636-6306080SDB2a1CRUAcrux [c] Deleted (0.00 magnitude - obviously wrong. The position is in the extreme S.W. of Vela, near non-descript NGC 2547) 081334-5012000SSK6 [d] Name Changed 052617+2836165SSB7b TAUHath (old) 052617+2836165SSB7b TAUAlnath (new) Note: beta Taurii == lambda Aurigae (above) [e] Mag limit: _ 064509-1643146SDA1a CMASirius (-1.46 not representable) 064509-1643-99SDA1a CMASirius Sirus has been reduced from mag -1.46 to -.99, owing to limitations in the three character positions used to give magnitude. This may be rectified by using the old style format (style is checked on a line and not a file basis), but this would remove spectral information and identification. [f] Known Problems and "Features" For certain double stars (when the companion is rather bright), duplicate entries exist in the dataset, Ra and Dec values matching exactly. The plotting of the second visible double star in an exact overstrike position can cause problems, particularly with PostScript, which will inadvertently form an annulus symbols which resembles the variable star indicator. The fix is to remove all duplicate entries from yale.star which are exact matches in RA and DECL, omitting those stars of lower value, while insuring that the parent star has a "SD" (star double) indicator. This has been done to roughly seventy stars in the database, notibly to Orion's belt and his Trapezium, and to Alpha Centaurii. The omitted entries are included in "yale.omit". These remain useful for checking the combined magnitudes of bright double stars, or in searching for pairs with striking difference in star spectral class. The best known example of the latter in the Northern Hemisphere is beta Cygnii [Alberio], but as the locations of both companions differ by 2" in RA, the parent star of spectral class K5 is represented, together with its B8 compainion. [g] Bayer and Flamsteed numbers A two character field represents Bayer letters, which by convention are assigned as Greek lower case letters from alpha to omega, followed by assignments in single and double digit Roman type. The database contains entries such as " A" and "A " and "a ", and it is not always clear that the lower case letter in the first column is an exact "trigger" for Greek fonts. (Because entries such as "@" indicate a theta, and "E" also occurs). In practice, this is not a problem unless one desires an authoratative code for a quite dim star (ie, beyond the 24th Bayer assignment). For virtally all stars given labels in standard Atlases, the StarChart output provides an exact match. [3] User Extentions to yale.star Barring the correction of obvious errors in yale.star, users may wish to add additional stars or ephemeride data in .star format. In any case, data should be for the epoch E2000.0. The program "epoch" may be used if this is not the case. The data records may be in either the new or old reduced file format convention (planet.star still produces data in the old format). The old format omits provision for spectral class or secondary label information, but allow stars of magnitude at or below 10.0, as four (and not three) characters are allocated to magnitude. Because testing of format is done on a line-by-line basis, entries may be mixed and matched. Thus, the present yale.star could be extended with data for dim, nameless stars below magnitude 10. Note that yale.star must be sorted in order of decreasing magnitude. This is only important for stellar data records. For other cases, data produced in .star format may be included for printing under the "-f file.star" option in the starcharting software. The important fields are for Ra, Decl, Magnitude, Type (code and subcode) and name, as each directly controls the location and appearence of the output. Two addition record types have been added to facilitate general plotting (such as lunar limb profiles or the ecliptic). The "I" type is an invisible object of some specified magnitude and location which serves as a means to annotate output. The "V" type is a vector object with subcodes "M", "S", "D", and "H" for move, solid-draw, dot-draw and hyphen(dash)-draw. Annotations are ignored for vector records, because the task of disentangling the intermingling of text and vector commands to a large class of output devices is formidable. Again, magnitude comes into play in performing clipping of objects too dim for display. A sample file of these record types appears in "ephem.star"