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\IBVShead{4655}{17 December 1998}

\IBVStitletl{NEW CATALOGUE OF SUSPECTED VARIABLE STARS.}{ SUPPLEMENT --- VERSION 1.0}

\IBVSauth{E.V. Kazarovets$^1$, N.N. Samus$^1$, O.V. Durlevich$^2$}
\IBVSinst{Institute of Astronomy, Russian Academy of Sciences, 48,
Pyatnitskaya Str., Moscow 109017, Russia\\ elena\_k@sai.msu.su,
samus@sai.msu.su} \IBVSinst{Sternberg Astronomical Institute, Moscow
University, 13, Universitetsky Ave., Moscow 119899,
Russia\\ gcvs@sai.msu.su}

\IBVSabs{A preliminary version of the supplement to the New Catalogue
of}
\IBVSabs{Suspected Variable Stars, containing 11206 stars, has been
compiled}
\IBVSabs{and is now available in electronic form.}

\IBVSkey{variable stars, suspected; catalogues}

\begintext

In the course of systematization and evaluation of data on
photometrically unstable objects, we have compiled a preliminary
catalogue of suspected variables (version 1.0) which is a natural
continuation of the New Catalogue of Suspected Variable Stars (NSV
Catalogue; Kukarkin et al., 1982). This Supplement to the NSV Catalogue
contains information on 11206 stars suspected in variability, in most
cases, within the recent 20 years. The new catalogue numbers of
suspected variable stars begin with No. 15001, to avoid confusion with
the NSV catalogue. In the system of the GCVS, this is the first
catalogue presenting the new accuracy standard (to 1--2 arcsec) for
coordinates of variability suspects in our Galaxy. It presents
photometric and spectral-type data, possible variability types,
additional information (on duplicity or multiplicity, large proper
motion, revealed mistakes, etc.), along with identifications, whenever
possible, with well-known general and special catalogues, thus
reflecting specific features of objects entering corresponding
catalogues and enabling us to considerably reduce the needed volume of
verbal remarks. Compared to 33 tables of identifications with different
catalogues available to users of the GCVS and the NSV Catalogue, the
Supplement to the NSV Catalogue gives identifications of its stars with
more than 50 different catalogues.

Detailed references to catalogues and lists used for identifications
(with author names, complete names of catalogues, and bibliographic
descriptions) and byte-by-byte descriptions of the Supplement's tables
can be found in the readme file of the electronic version, NSVSUP, of
the present Supplement.

The main table of the Supplement to the NSV Catalogue is a compact
presentation of data resulting from the analysis of photometric and
spectroscopic information contained in more than 50000 bibliographic
descriptions currently constituting the Supplement's ever growing data
base.  We hope that this compact and formalized presentation of data
for each star will facilitate users' orientation in the tremendous
volume of available information. In our understanding, the catalogue's
main goal is to provide necessary data on each variable star making it
possible to locate it, rather easily, on the sky, to find it in other
catalogues, and, whenever possible, to get an idea about the character
of variability. It may serve the international community of variable
star researchers as a tool for designing observing programmes: each
suspected variable, after thorough investigation, can enter the General
Catalogue of Variable Stars, and some of them may even become new
prototypes in variability classification.

Observers need high accuracy of coordinates for variable stars.
According to practical requirements of ground-based and orbital
observations, to typical parameters of seeing and of automatic
telescope pointing, we tried to achieve an accuracy about 1 arcsec for
objects of our catalogue.  Such positional accuracy will, most
probably, exclude ambiguity in pointing to the majority of objects,
except variable components of multiple systems needing individual
approach to identification of each of the closely located companions.
Such accuracy of coordinates also makes it possible to undertake
automatic identifications of most variable stars with objects of
numerous modern electronic catalogues.

For variables down to 9th--10th magnitudes, we accepted coordinates
from SAO or PPM catalogues. The Hubble Space Telescope Guide Star
Catalogue enabled us to improve coordinates for the majority of fainter
stars (to 14th--15th magnitudes). We used the USNO A1.0 catalogue to
find positions of still fainter stars (to the limit of Sky Surveys,
21--22\mm). For faint stars not contained in the latter two catalogues,
we determined coordinates relative to GSC stars. For each star having a
finding chart, we compared the chart with the image of the
corresponding star field created using the visualization software
kindly provided by A.A. Volchkov (Sternberg Astronomical Institute) for
the GSC and by J. Manek (Stefanik Observatory, Czech Republik) for the
USNO A1.0 catalogue. We rounded the resulting coordinates to 0.1 second
of time in right ascension and to 1 arcsecond in declination. GSC
numbers for the stars of the NSV Supplement are included into the table
of identifications. The number of the Supplement's stars with GSC
identifications is 5921 (or 53\%), 160 of them having simultaneously
two or more GSC numbers.

In the electronic version of the Supplement, the coordinates of
suspected variables are presented for two equinoxes, B1950.0 and
J2000.0. The numbering of stars in the catalogue follows increasing
right ascension for the equinox B1950.0: all our variable star
catalogues and the majority of special catalogues give positions for
this equinox. Only recently, many catalogues began to choose the
equinox J2000.0, thus making it necessary to transform the coordinates
in the catalogues of variable stars (GCVS and the NSV Catalogue) to
J2000.0. In the process of this transformation for the GCVS, currently
under way in our group, we also find and identify each star and improve
its coordinates; for the Supplement to the NSV Catalogue, we have
already solved these problems during its compilation, so the
transformation was straightforward.

Among the stars of the Supplement, there are 1956 stars suspected in
variability in the cause of the orbital observations of the Hipparcos
experiment. The manner of presentation of Hipparcos variables in our
catalogue does not differ from that used for the rest of suspected
variables; we have adjusted the variability types suggested in the
Hipparcos catalogue according to the standard GCVS classification. The
Hipparcos variables in the Supplement to the NSV Catalogue are mostly
stars with information insufficient for reliable determination of their
variability types, so that they could not be assigned GCVS names and
included into the special, 74th Name-List of Variable Stars (to be
published in the IBVS in the nearest future). A number of stars were
not named because of their spectroscopic and/or photometric
characteristics contradicting the existing variability types (thus,
either re-reductions of data or new observations are needed, for
example, to check the period of brightness variations, the luminosity
class, etc.).

\IBVSfig{18.6cm}{4655-f1.eps}{The brightness distribution in $V$ and $B$ bands for stars
of the Supplement to the NSV Catalogue}

\vspace{-\baselineskip}
For each of the 118322 stars of the Hipparcos catalogue, more than 100
homogeneous brightness measurements, gathered during 4 years of orbital
observations (1989--1993), in the Hipparcos system, are available on
CD-ROM. So it was important to identify stars of our Supplement with
those Hipparcos catalogue stars not recognized as variables. We got
1420 such identifications and included them into the identification
table, thus enabling the users to combine data of our catalogue with
Hipparcos observations and to determine, for some stars, variability
types not found by the ESA scientific team.

We are planning to add cross-identification tables arranged in the
order of numbers of external catalogues and making it possible to find
corresponding GCVS names or NSV/NSV Supplement numbers.

Figure 1 shows the brightness distribution ($V$ and $B$ light) for the
stars of the NSV Supplement. In the upper panel, we also demonstrate
the contribution of Hipparcos discoveries of variable stars to the NSV
Supplement. Among the stars of the Supplement, $V$ magnitudes are
presented for slightly more than 50\% of them; $B$ magnitudes, for
about 10\%; the rest of the stars have magnitudes presented in other
bands. In the NSV Catalogue proper, two thirds of stars had
photographic or $B$ magnitudes.

The NSVSUP Catalogue is available by INTERNET, at the GCVS home page of
the Sternberg Astronomical Institute:

\centerline{
\vbox{
\hbox{
ftp ftp.sai.msu.su, /pub/groups/cluster/gcvs/gcvs/nsvsup/ (anonymous) }
\hbox{
http://www.sai.msu.su/groups/cluster/gcvs/gcvs/nsvsup/ }
\hbox{
E-mail: gcvs\@sai.msu.su }
}
}

This study was supported, in part, by the Russian Foundation for Basic
Research (grant 97-02-16739), by the Federal Scientific Programme
``Astronomy'' (project 2.2.1.6), and by the Russian Programme of
Support for Leading Scientific Schools (grant 96-15-96656).

\references

Kukarkin, B. V., Kholopov, P. N., Artiukhina, N. M., Fedorovich, V. P.,
Frolov, M. S., Goranskij, V. P., Gorynya, N. A., Karitskaya, E. A.,
Kireeva, N. N., Kukarkina, N. P., Kurochkin, N. E., Medvedeva, G. I.,
Perova, N. B., Ponomareva, G. A., Samus, N. N., and Shugarov, S. Yu.,
1982, {\it New Catalogue of Suspected Variable Stars} (Moscow: Nauka
Publishing House)

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