The VSTARS database contains the machine-readable version of the General Catalog of Variable Stars (GCVS), 4th Edition (Kholopov et al. 1985-1988).


The name of the star as given in the catalog; the generally adopted system 
of variable star designations has been used.  This nomenclature system follows
the sequence R,...,Z, RR,...,ZZ, AA,...,QZ, V 335,..., and so on.
The right ascension of the star.
The declination of the star.
The galactic longitude of the star.
The galactic latitude of the star.
The BROWSE internal object class flag.
The magnitude of the star at maximum light. The precision varies, with most
magnitude data reported to one tenth, meaning that the magnitudes have been
determined by ordinary photographic or visual means.  Photoelectric magnitudes
are reported to hundredths.  In some cases, the maximum magnitude is given to
tenths and the minimum reported to hundredths.  This means that the light
amplitude was accurately determined photoelectrically, but an accurate
magnitude was not measured for the comparison star(s).  In other cases, the
maximum is given to hundredths and the minimum to tenths.  Here, the maximum
has been determined photoelectrically, while the light amplitude is based on
photographic or visual observations. 

Reported magnitudes are usually just those given in corresponding published
papers; i.e., no "GCVS magnitude system" exists.  However, in cases where
published magnitudes are expressed on old photographic or visual systems used
in the late 19th and early 20th centuries, the compilers of the GCVS have
attempted to transform them to modern magnitude scales by means of
corresponding empirical corrections.  Generally, magnitudes corresponding to
the brightest maximum and faintest minimum ever observed are given.  Average
magnitudes reported by observers for maximum and minimum light have been used
only in cases of doubtful visual or photographic observations; in such cases,
the GCVS compilers took care to guarantee that the amplitudes recorded by those
observers would not be artificially increased. 
The same comments as for maximum magnitude with regard to precision apply here. 
At times there is no value for `vmin`; in these cases, the value 0.0 is given. 
If a small value is given (e.g., 0.3), `vmin` is the differential magnitude.
The Vmag codes are as follows:
  ( = the star is fainter at minimum light than the value given
  ) = the star is brighter at maximum light than the value given
 () = the value is a differential magnitude, and is given to thousandths
      of a magnitude 
  : = uncertain value
A Vmag code of U,B,V,R,I,J,H,K,or L indicates that the value for a differential
magnitude is given for a passband of the broadband UBVRIJHKL system.
The name and number of the catalog in which the variable appears.  
(This database parameter is no longer necessary, but is left over from when the
GCVS was combined with Kukarkin's Catalog of Suspected Variables into a
single database called VSTARS.  As of September 1991, the VSTARS database
contains only the GCVS, and a database called VSTARSUSP now contains the
Kukarkin catalog.)
0 if the object is a single star; 1 if it is a component of a 
multiple-star system.
An improved system of variability classification is used in the fourth edition
of the GCVS, based on recent developments in classification principles and
taking into account the suggestions of a number of specialists.  Variability
types are grouped according to the major astrophysical reasons for variability,
viz., eruptive, pulsating, rotating, cataclysmic (explosive and novalike)
variables, eclipsing binary systems, and intense variable X-ray sources.  All
of these classes include objects of a dissimilar nature that belong to
different types of light variability.  On the other hand, an object may be
variable because of almost all of the possible reasons or because of any
combination of them.  If a variable belongs to several types of variability,
the types are joined in the data field by a "+" sign, e.g., E+UG, UV+BY.

Below is a table of brief descriptions of variability types; more complete
descriptions can be found in Volume 1 of the GCVS, and in the documentation 
for its machine-readable version (Warren 1988).  
      Abbreviation          Description
      ------------          ---------------
        ACV                 Alpha-squared Canum Venaticorum
        BCEP                Beta Cephei
        BL                  BL Lacertae
        BY                  BY Draconis
        CEP                 cepheid
        CST                 constant
        CW                  W Virginis
        DCEP                Delta Cephei
        DSCT                Delta Scuti
        E                   eclipsing
        EA                  Algol (Beta Per)
        EB                  Beta Lyrae
        EW                  W Ursae Majoris
        ELL                 ellipsoidal
        GCAS                Gamma Cassiopeiae
        I                   irregular
        IA                  white irregular
        IN                  irregular in a nebula
        INS                 rapid irregular in a nebula
        INT                 irregular of the T Tauri type
        IS                  rapid irregular
        L                   slow
        LB                  slow red
        M                   Mira (o Ceti) type
        N                   nova
        NL                  novalike
        QSO                 quasistellar object
        RCB                 R Coronae Borealis
        RR                  RR Lyrae
        RRC                 RRC
        RV                  RV Tauri
        S                   rapid
        SDOR                S Doradus
        SR                  semiregular
        SN                  supernova
        UG                  U Geminorum
        UV                  UV Ceti
        UVN                 UV Ceti in a nebula
        ZAND                Z Andromedae
        ZCAM                Z Camelopardalis
        ZZC                 ZZ Ceti
The photometric system in which the magnitudes are reported.  The system
coded applies to both magnitudes or to the maximum light magnitude and delta-m,
except where there is a passband identified in the `Code Vmag` field.  The
following codes are present:
 * P = the reported magnitudes are photographic;
 * V = the magnitudes are visual, photovisual, or V of the Johnson and Morgan
       UBV system.  The latter can be distinguished by the increased precision
       to which the values are given (thousandths).  The V passband is centered
       at lambda = 550 nm, delta - lambda = 89 nm.
Other uppercase letters are used to denote, generally, passbands of the
broadband UBVRIJHKL system; unfortunately, the use of all uppercase characters
in the catalog does not allow one to distinguish between R and other red (r)
magnitudes, nor between I and other infrared (i) magnitudes.  The following
list gives the characteristics of the broadband system:
  Filter          Effective              Effective        Absolute Spectral
   Band           Wavelength             Bandwidth       Irradiance for Mag 0.0
                                                            (W m-2 nm-1)
  ------          ----------             ----------     ----------------------
    U                360                     68             4.27 x 10-11
    B                440                     98             6.61 x 10-11
    V                550                     89             3.64 x 10-11
    R                700                    220             1.74 x 10-11
    I                900                    240             8.32 x 10-12
    J               1250                    300             3.18 x 10-12
    H               1650                    400             1.18 x 10-12
    K               2200                    578             4.17 x 10-13
    L               3600                   1200             6.23 x 10-14
Spectral types are reported in the MK system when available.  In cases where
multiple types are available, more recent classifications were generally
preferred, with some account being taken of reliability if this was possible. 
The following comments regarding the reported spectral types are made in the
introduction to the published catalog:

(1)  The luminosity indicators "d" and "g" generally associated with Mt.
Wilson types have been replaced by the corresponding luminosity classes "V"
and "III" of the MK system, respectively;

(2)  The "C" types for carbon stars were preferred, if available, with
temperature and abundance indices (e.g., C6,3) usually followed by the old
types (R or N) in parentheses;

(3)  Semiregular variables having F, G and K types occasionally display TiO
bands.  In such cases, the principal spectral types are followed by the TiO
types given in parentheses, or their presence is indicated in the remarks.  For
M-type stars displaying ZrO bands, the M types are followed, with or without
parentheses, by the type "S";

(4)  Orion variables displaying characteristic T Tauri features contain the
letter "T" in parentheses following their spectral types;

(5)  The catalog remarks sometimes report the spectral types for S stars at
maximum light according to the new system described by Keenan and Boeshaar

(6)  The symbols "OB" denote that a star's spectral type is earlier than F
and that it lies above the main sequence;

(7)  For novae studied spectroscopically and displaying characteristic outburst
spectra, the spectral-type field contains "PEC(NOVA)".  On the other hand, if
a star's spectrum displays features characteristic of U Gem variables, this is
indicated by "PEC(UG)".  Continuous spectra are denoted by "CONT", while
the symbol "E" indicates an emission spectrum and "EA" is used for stars
having H-alpha emission;

(8)  Hydrogen spectral types are given for RR Lyrae variables; remarks may
contain values of [Fe/H] or [A/H], the values (k+b)2, and/or the value 
(Delta S) = 10[Sp(H) - Sp(Ca II)] at minimum light in order to estimate heavy 
element abundances in a star's atmosphere;

(9)  The symbol "+" joining adjacent types denotes that two spectra are
observed, while a "-" signifies limits of spectral variations observed during
light variations. 
Coded number for constellation identification.  The numbers are assigned
sequentially to the constellation abbreviations (And - Vul) in alphabetical
order.  See the help topic "Numerical Constellation Codes" for a table
listing numerical code assignments.
Numbers are assigned sequentially within each constellation according to the
standard sequence of variable-star designations (R, S,...).  This code allows
for simplified sorting according to variable-star designation, ordinarily a
difficult procedure because of the nonstandard sequence used for name
assignments.  There are 334 letter designations followed by numerical codes
corresponding to V 335, V 336, etc.
Annual precession, given in seconds of time.
Annual precession, given in arc minutes.
Units are Julian days.  Epochs are given for MINIMUM light for all eclipsing
and ellipsoidal variables, as well as for RV Tau and RS CVn types, and for
MAXIMUM for all other types.  (This rule may occasionally be broken, but this
is explained only in the remarks to the catalog, which are not available in
machine-readable form at this time.)

For well-studied Miras (M) and some semiregulars (SRa-d), the catalog usually
gives one of the most recent epochs of maximum light.

Epochs for novae (types N) and supernovae (types SN) are given in Julian days
followed by a year of outburst enclosed in parentheses.  

Epoch values may be followed by a code, which should be translated as follows:
 * : = uncertain value
 * + = the epoch may be later than that reported
 * - = the epoch may be earlier than that reported
Period data were often checked by the catalog compilers, with new periods being
determined in many cases, and/or period changes were revealed.  For
well-studied Miras and some semiregulars having reasonably constant
periodicities, mean values of the periods for the entire observed intervals are
usually reported, since they may be considered the most probable values for
predicting future epochs.  However, for stars with definite period variations,
the "Remarks" in the published catalog give the elements best describing a
star's behavior during different time intervals in the past, since this
information will hopefully allow the determination of sufficiently accurate
light maxima and minima.  

Formal (double) periods are usually reported for RV Tau stars and fundamental
periods for semiregulars.  For U Gem and recurrent novae, the mean cycle values
are given if known.  These are denoted as differing from the periods of regular
and semiregular variables by the presence of parentheses around the value. 
Other comment codes are:  "N", which indicates that the actual period is
unknown, whereupon the value given is only a time interval between two maxima
or minima separated by an unknown number of cycles; and ":" which indicates an
uncertain value.
This is the duration of light increase from minimum to maximum (M-m) for
physical variables, or the duration of eclipse (D) for Algol-type stars.  The
values, in many cases, have been derived by the catalog compilers on the basis
of all reliable independent determinations, with an indication of their
approximate accuracy contained in the reported values.  Photoelectric values
were strongly preferred.  A colon (":") indicates an uncertain value, while an
asterisk (*) means that the duration of the light constancy phase at minimum
light (d) for an eclipser is equal to zero.

Numerical Constellation Codes

The table below gives the numerical code assignments used in the GCVS for the 88 constellations. The three-letter abbreviations are those adopted by the International Astronomical Union for standard usage, except that they are, of course, all in uppercase characters in the GCVS.
Code    Const           Code    Const           Code    Const		

01      AND             32      DEL             63      PER
02      ANT             33      DOR             64      PHE
03      APS             34      DRA             65      PIC
04      AQR             35      EQU             66      PSC
05      AQL             36      ERI             67      PSA     
06      ARA             37      FOR             68      PUP
07      ARI             38      GEM             69      PYX
08      AUR             39      GRU             70      RET
09      BOO             40      HER             71      SGE 
10      CAE             41      HOR             72      SGR
11      CAM             42      HYA             73      SCO
12      CNC             43      HYI             74      SCL
13      CVN             44      IND             75      SCT	
14      CMA             45      LAC             76      SER 
15      CMI             46      LEO             77      SEX 
16      CAP             47      LMI             78      TAU 
17      CAR             48      LEP             79      TEL
18      CAS             49      LIB             80      TRI
19      CEN             50      LUP             81      TRA
20      CEP             51      LYN             82      TUC
21      CET             52      LYR             83      UMA 
22      CHA             53      MEN             84      UMI
23      CIR             54      MIC             85      VEL
24      COL             55      MON             86      VIR
25      COM             56      MUS             87      VOL
26      CRA             57      NOR             88      VUL
27      CRB             58      OCT		
28      CRV             59      OPH		
29      CRT             60      ORI		
30      CRU             61      PAV
31      CYG             62      PEG


The present documentation has been adapted almost entirely from "Documentation for the Machine-Readable Version of the General Catalog" (Warren, NSSDC, June 1989). Consult that document, or the General Catalog itself, for more detailed information about the Catalog.

Contact Person

Questions regarding the VSTARS database table can be addressed to the HEASARC User Hotline.
Page Author: Browse Software Development Team
Last Modified: Thursday, 18-Jul-2002 12:56:08 EDT