The VSTARS database contains the machine-readable version of the General
Catalog of Variable Stars (GCVS), 4th Edition (Kholopov et al. 1985-1988).
Name
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.
RA
The right ascension of the star.
Dec
The declination of the star.
LII
The galactic longitude of the star.
BII
The galactic latitude of the star.
Class
The BROWSE internal object class flag.
Vmax
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.
Vmin
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.
Code_Vmag
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
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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.
Catalog_and_Catalog_Number
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.)
Multiplicity_Flag
0 if the object is a single star; 1 if it is a component of a
multiple-star system.
Type_of_Variability
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).
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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
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Mag_Band
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
-------------------------------------------------------------------------------
Spectrum_Classification
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
(1980);
(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.
Constellation_Number
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.
Star_Number
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.
Precession_RA_1950
Annual precession, given in seconds of time.
Precession_Dec_1950
Annual precession, given in arc minutes.
Epoch_JD
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
---
Periods_JD
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.
Duration
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.
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.
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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
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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.
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
