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An Electronic Version of the Second Volume of the General Catalogue of
Variable Stars with Improved Coordinates

N.N. Samus', V.P. Goranskii, O.V. Durlevich, A.V. Zharova, E.V. Kazarovets,
N.N. Kireeva, E.N. Pastukhova, D.B. Williams, and M.L. Hazen,

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Astronomy Letters, Vol. 29, No. 7, 2003, pp. 468-479. Translated from
Pis'ma v Astronomicheskii Zhurnal, Vol. 29, No. 7, 2002, pp. 532--544.

Russian Academy of Sciences, ul. Pyatnitskaya 48, Moscow, 109017 Russia
Sternberg Astronomical Institute, Universitetskii pr. 13, Moscow,
119899 Russia
Harvard Observatory, 60, Garden Str., Cambridge, MA, 02138 USA

Received February 5, 2003
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We present a new electronic version of the second volume of the fourth edition
of the General Catalogue of Variable Stars (GCVS), containing data on 13480
variable stars in the constellations Cygnus - Orion (the order of
constellations in the catalogue follows the Latin alphabet). The version
takes into account the Name-lists of Variable Stars, from No. 67 to No. 77,
for the same constellations. The most important feature of the new version is
that it contains improved equatorial J2000.0 coordinates for 13446 stars
(for 5052 of them, with proper motions accounted for), based upon
identifications with positional catalogues using finding charts as well as
upon our new measurements. Our search for a number of stars made use of
original plates from collections of several observatories and of images
provided by digital sky surveys. The version also includes a file with remarks
to the second and third volumes of the GCVS. Besides the complete revision of
the positional information, the new version comprises some necessary
corrections that became known after the publication of the second GCVS volume
(1985). We present references to corresponding new Internet resources.

Key words: stars - variable and peculiar

www.sai.msu.su/groups/cluster/gcvs/gcvs/vol2/
ftp.sai.msu.su/pub/groups/cluster/gcvs/gcvs/vol2/

File Summary:
-----------------------------------------------------------------
FileName Explanations
-----------------------------------------------------------------
readme.txt This file
vol2.pdf The text of the paper
vol2.dat The new electronic version of volume I of the GCVS4
vol2_pos.dat The positional information for the stars of volume I
of the GCVS4
rem.txt The list of remarks to volume I
-----------------------------------------------------------------

The file vol2.dat
-------------------

The main table (vol2.dat) of the new electronic version of volume I
of the GCVS contains information on 13780 objects (not counting the
stars that were erroneously named for the second time or proved to be
nonexistent) in Cygnus - Orion, which are mostly variable stars of
our Galaxy discovered and named before 2001; i.e., it covers the
variable stars that were included in the fourth edition of the GCVS and
name lists nos. 67 - 77 (for the same constellations).

The structure of the main table corresponds to that of the combined
table of the GCVS 4th edition and the name lists (Kholopov et al. 1998;
see also www.sai.msu.su/grops/cluster/gcvs/gcvs/iii/). The differences
between these tables are as follows:

(1) Instead of B1950.0 coordinates, we provide new improved equatorial
J2000.0 coordinates.

(2) The most recent name lists, up to no. 77, were included.

(3) We included all the corrections and changes that were found
necessary during our work on the GCVS in other columns of the main
table, in references, and in remarks. Note that for stars that had no
published finding charts but that we identified with the GSC or with the
US Naval Observatory (USNO) A1.0/A2.0 catalogs, we now give a symbol of
the corresponding catalog (GSC, USNO) as a reference to the finding
chart.

The main table is presented in the form traditional for the GCVS, i.e.,
in the order of constellations and variable-star names adopted in the
GCVS. The table includes the following information: equatorial J2000.0
coordinates (right ascensions to within 0.1s and declinations to within
1"), variability types, magnitudes at maximum and minimum light,
photometric magnitude systems, periods of light variations, durations of
brightness rise from minimum to maximum of eclipse durations, spectral
types, and bibliography. For the stars from name lists no. 67 - 77
published after the appearance of the GCVS 4th edition, we provide not
all columns of the table but only coordinates, variability types,
magnitudes, and bibliography; the missing data will be added to the 5th
edition of the GCVS.

Byte-by-byte Description of file: vol2.dat
------------------------------------------------------------------------------
Bytes Format Units Label Explanations
------------------------------------------------------------------------------
1- 2 I2 --- Constell [1/88]Constellation numeric code
3- 6 I4 --- Number Star number within the constellation
7 A1 --- Component Component identification
9- 18 A10 --- GCVS Variable star designation
19 A1 --- NoteFlag [*] Notes in published catalog
(see file rem.txt)
21- 22 I2 h RAh Hours RA, equinox J2000.0
23- 24 I2 min RAm Minutes RA, equinox J2000.0
25- 28 F4.1 s RAs Seconds RA, equinox J2000.0
29 A1 --- DE- Sign Dec, equinox J2000.0
30- 31 I2 deg DEd Degrees Dec, equinox J2000.0
32- 33 I2 arcmin DEm Minutes Dec, equinox J2000.0
34- 35 I2 arcsec DEs Seconds Dec, equinox J2000.0
36 A1 --- u_DEs *[:*] position accuracy flags
38- 47 A10 --- VarType Type of variability(see file
www.sai.msu.su/grops/cluster/gcvs/gcvs/iii/vartype.txt)
49 A1 --- l_magMax [<>(] ">" if magMax is a faint limit
"<" if magMax is a bright limit
"(" if magMax is an amplitude
50- 55 F6.3 mag magMax Magnitude at maximum brightness
56 A1 --- u_magMax Uncertainty flag (:) on magMax
56 A1 --- n_magMax Alternative photometric system for magMax
57 A1 --- f_magMax [)] ")" if magMax is an amplitude
59 A1 --- l_magMin [<(] "<" if magMin is a bright limit
"(" if magMin is an amplitude
60- 65 F6.3 mag magMin Minimum magnitude or amplitude
66 A1 --- u_magMin Uncertainty flag (:) on magMin
67- 68 A2 --- n_magMin Alternative photometric system for magMin
69 A1 --- f_magMin [)] ")" if magMin is an amplitude
71- 72 A2 --- magCode The photometric system for magnitudes
74- 84 F11.5 d Epoch Epoch for maximum light, Julian days
85 A1 --- q_Epoch [:+-] Quality flag on Epoch
86- 90 A4 --- YearNova Year of outburst for nova or supernova
91 A1 --- q_Year [:] Quality flag on Year of outburst
93 A1 --- l_Period [<>(] Code for upper or lower limits
94-109 F16.10 d Period Period of the variable star
110 A1 --- u_Period Uncertainty flag (:) on Period
111-112 A1 --- n_Period [*/N)]
114-116 A3 % M-m/D Rising time (M-m) or duration of eclipse (D)
117 A1 --- u_M-m/D Uncertainty flag (:) on M-m/D
118 A1 --- n_M-m/D [*] Note for eclipsing variable
120-136 A17 --- SpType Spectral type
138-142 A5 --- Ref1 Reference to a study of the star (ref.txt)
144-148 A5 --- Ref2 Reference to a chart or photograph (ref.txt)
150-161 A12 --- Exists Cases of non-existence of the variable etc.
-------------------------------------------------------------------------------

POSITION ACCURACY FLAGS -
(*) - So far we have failed to determine accurate coordinates for 207
variable stars, because there are no finding charts and because the
information for star identification is insufficient. The coordinates
that could not be improved were recalculated from old rough coordinates
to the equinox J2000.0 with allowance for precession.
(:) - A flag indicating that the coordinates are actually rougher than
the new accuracy standard adopted in the table vol2_pos.dat (see below).


The file vol2_pos.dat
---------------------

For 13447 variable stars, our version provides new equatorial J2000.0
coordinates (right ascensions to within 0.01s and declinations to within
0.1"), for 5056 stars with allowance for their proper motions.

The table vol2_pos.dat provides positional information based on our
identifications with major astrometric catalogs, on published data, or
on our new measurements (see below) for 13447 stars of the new version
of volume II (including stars of the new name lists in the same
constellations). The order of stars in this table is the same as that in
the main table.

Byte-by-byte Description of file: vol2_pos.dat
------------------------------------------------------------------------------
Bytes Format Units Label Explanations
------------------------------------------------------------------------------
1- 2 I2 --- Constell [1/88]Constellation numeric code
3- 6 I4 --- Number Star number within the constellation
7 A1 --- Component Component identification
9- 18 A10 --- GCVS Variable star designation
20- 21 I2 h RAh Hours RA, equinox J2000.0
22- 23 I2 min RAm Minutes RA, equinox J2000.0
24- 28 F5.2 s RAs Seconds RA, equinox J2000.0
30 A1 --- DE- Sign Dec, equinox J2000.0
31- 32 I2 deg DEd Degrees Dec, equinox J2000.0
33- 34 I2 arcmin DEm Minutes Dec, equinox J2000.0
35- 38 F4.1 arcsec DEs Seconds Dec, equinox J2000.0
39 A1 --- u_DEs *[:] position accuracy flag
41- 46 F6.3 arcsec/yr PMa Proper motion RA
48- 53 F6.3 arcsec/yr PMd Proper motion DE
55- 62 F8.3 yr Epoch *Epoch
64 A1 --- u_Ident *Uncertainty flag (?) on identification
66- 77 A12 --- Ident *The source of astrometric data
-------------------------------------------------------------------------------

POSITION ACCURACY FLAG (:) - indicating that the coordinates are
actually rougher than the new accuracy standard adopted in the catalog,
because we failed to determine better coordinates and to find them in
source catalogs or in publications. In comparatively numerous cases,
such coordinates were obtained by transforming B1950.0 coordinates from
the IRAS Point Sorce Catalog (see below).

EPOCH of the given coordinates. No epoch is provided when using the
coordinates from the literature if the epoch was no specified in the
publication and cold not be established;

FLAG (?) ON IDENTIFICATION - the variable star's identification with
the source catalog is uncertain;

THE SOURCE OF ASTROMETRIC DATA - A brief designation of the source of
astrometric data. In several cases, the catalog designation is folowed
by the symbol "+pm"; it implies that the position for a certain epoch
was taken from the catalog and reduced to the epoch 2000.0 using
information on the star's proper motion from a different source.

Below, we give a list of the major catalogs and other data sources used,
roghly in the order of our preference in identifying variable stars
(see also the description of the catalogs provided for A.A. Volchkov's
visualization code we used at www.simfov.ru).

Hip - The Hipparcos Catalogue (ESA 1997).

Tyc2 - The Tycho Catalogue (Hog et al. 2000). In isolated instances
where the star is absent in the second Tycho catalogue but is present in
the first catalogue (ESA 1997), the source is indicated as Tyc1.

PPM - The Positions and Proper Motions (Roser et al. 1991-1993).

NPM - The Lick Northern Proper Motion Program (Klemola et al. 1987).

AC - The Four-Million Star Catalog (see Gulyaev and Nesterov 1992).

ACT - The ACT Reference Catalog (Urban et al. 1997).

FASTT - coordinates of variable stars (in the equatorial region of the
sky) measured with the Flagstaff Astrometric Scanning Transit Telescope
of the US Naval Observatory (Henden and Stone, 1998).

GSC 2.2 - The Guide Star Catalog, Version 2.2.01, 2001, Space Telescope
Science, Institute and Osservatorio Astronomico di Torino.

UCAC1 - US Naval Observatory CCD Astrograph Catalog (Zacharias et al.,
2000).

GSC - The Guide Star Catalog (Lasker et al. 1990). The symbol "ns"
accompanying a GSC reference implies that the entry is marked as a
nonstellar object in the cited catalog.

A2.0, B1.0 - A Catalog of Astrometric Standards (Monet et
al., 1998) (there were rare cases when the star could be found only in the
previous version of the catalogue, marked as A1.0); The Whole-Sky USNO-B1.0
Catalog of 1 045 913 669 Sources (Monet et al., 2003).

2MASS - The Two Micron All Sky Survey (Skrutskie et al., 2000).

IRAS - The Infrared Astronomical Satellite Catalogue of Point Sources
(Neugebauer et al. 1988). We used it only when it was impossible to
identify a star with positional catalogs or to find a star at optical
wavelengths and independently measure its coordinates.

GCVS AUTHORS - For some 330 stars (2.5% of the total number of stars in
the new version), the coordinates were measured by the authors using
Digitized Sky Survey images, plates from different collections, or other
images. The source of the coordinates is given as "GCVS authors" in
such cases. As a rule, we applied GSC2.2 or A2.0 catalogue stars as
reference stars in our measurements using the Digitized Sky Survey. To
determine rectangular coordinates, we manually pointed the cursor to
photometric centers of stars in commercially available applications for
reductions of images, at large magnification. The reductions of the
measurements made use of Turner's linear method. The uncertainty of our
measurements was typically about 0.5" both in right ascension and in
declination.

LITERATURE - The coordinates taken from current astronomical periodicals.


The files rem.txt
------------------

The list of remarks to volume I (rem.txt) includes information that
supplements the main table for 3451 stars. In contrast to
the printed bilingual version of the 4th GCVS edition (Kholopov et al.
1985-1988), all remarks in the file are given only in English and
generally correspond to the English text of the remarks in the printed
edition. The remarks contain, in particular, information on variable
stars in double systems, on period variability, on secondary minima of
eclipsing variables, and on proximity to star clusters and nebulae in
the sky. For unique variable stars, the remarks give detailed
descriptions of the variability pattern.


Acknowledgments
---------------

We wish to thank T.M. Tsvetkova who prepared files of the remarks to
the GCVS Volumes II and III. The authors are grateful to A.A. Volchkov
and to J. Manek (Czech Republic) for providing us with necessary
software. Thanks are due to S.V. Antipin for assistance, to
L.N. Berdnikov for providing unpublished finding charts for a number of
southern Cepheids, to C. Lopez (Argentina) and P. Schmeer (Germany) for
making their results available prior to publication. This study was
financially supported, in part, by the Russian Foundation for Basic
Research (grant No. 02-02-16069), Program of Support for Leading
Scientific Schools of Russia (grant No. 00-15-96627), Federal Program
"Astronomy", and the program "Unstable Processes in Astrophysics" of
the Presidium of Russian Academy of Sciences. Our study made use of
Digitized Sky Survey images provided by the Hubble Space Telescope
Science Institute under support from the grant NAG W-2166 of the
Government of the USA and the data from the US Naval Observatory
Flagstaff Station Image and Catalogue Archive
(http://www.nofs.navy.mil/data/fchpix/). We are grateful to the
referee, Dr. L.R. Yungelson, for helpful criticism.



References
----------

1. E. Hog, C. Fabricius, V. V. Makarov, et al., The Tycho-2 Catalogue,
CD-ROM (Copenhagen, 2000).

2. P. N. Kholopov, N. N. Samus', M. S. Frolov, V.P. Goranskii, N. A.
Gorynya, E. A. Karitskaya, E. V. Kazarovets, N. N. Kireeva, N. P.
Kukarkina, N. E. Kurochkin, G. I. Medvedeva, N. B. Perova, A. S.
Rastorguev, and S. Yu. Shugarov, General Catalogue of Variable Stars
(Nauka, Moscow, 1985-1988), Vols. I-III.

3. P. N. Kholopov, N. N. Samus, N. M. Artiukhina, O. V. Durlevich, M. S.
Frolov, V. P. Goranskij, N. A. Gorynya, E. A. Karitskaya, E. V.
Kazarovets, N. N. Kireeva, N. P. Kukarkina, N. E. Kurochkin, N. A.
Lipunova, G. I. Medvedeva, E. N. Pastukhova, N. B. Perova, A. S.
Rastorguev, S. Yu. Shugarov, and T. M. Tsvetkova, Centre de Donnees
Astronomiques de Strasbourg, II/214A (1998).

4. A. R. Klemola, R. B. Hanson, and B. F. Jones, Centre de Donnees
Astronomiques de Strasbourg, I/199 (1987).

5. B. M. Lasker, C. R. Sturch, B. J. McLean, et al., Astron. J. 99,
2019 (1990).

6. C. Lopez, private communication (1998).

7. D. Monet, A. Bird, B. Canzian, et al., USNO-A V2.0. A Catalog of
Astrometric Standards (US Naval Observatory, Washington, 1998), 11 CD
ROMs.

8. G. Neugebauer, R. J. van Duinen, H. J. Habing, et al., IRAS Point
Source Catalog (NASA, Washington, 1988).

9. On the Four-Million Star Catalog, Ed. by A. P. Gulyaev and V. V.
Nesterov (Mosk. Gos. Univ., Moscow, 1992).

10. S. Roeser, U. Bastian, L. I. Yagudin, and V. V. Nesterov, PPM
Star Catalogue. Positions and Proper Motions (Astronomisches
Rechen-Institut, Heidelberg, 1991-1993).

11. The Hipparcos and Tycho Catalogues (European Space Agency, 1997),
ESA SP-1200.

12. S. E. Urban, T. E. Corbin, and G. L. Wyckoff, The ACT Reference
Catalog (US Naval Obs., Washington, 1997).

13. A. A. Volchkov and O. A. Volchkov, http://www.simfov.ru, 2001.