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\IBVShead{4328}{24 April 1996}       % Use it with dummy or empty arguments

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\title{OBSERVATIONS OF THE FLARE STAR V\,1929 Cygni}

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V1929 Cyg was discovered during the monitoring campaign for flare star
search based on the  photographic  patrol observations with the Asiago
60/92 cm Schmidt telescope in the region of the  NGC 7000 nebula. This star with
coordinates R.A. (1950.0) = 20\fh 55\fm 8,  Dec. (1950.0) =
43\degr 46' got
first designation A5 (Rosino et al., 1987).  According to the 69th Name
list  of  Variable  Stars (Kholopov et al., 1989) the star is named
V1929 Cygni. During the flare  event  on  September 4,  1972  the star
increased its brightness up to 14\fm 5 (pg).  V1929  Cyg is obviously
located near the V521 Cyg (LkH$\alpha$ 188) group of H$\alpha$-emission
and flare
stars in the star-forming region of the dark nebula ``Gulf of Mexico" in the North America nebula.
In Figure 1  the  identification  map of the star
from an 8 minute  exposed V-plate (Kodak 103aD+GG495) obtained with the 100/131
cm Byurakan Schmidt telescope on April 24, 1974 is given.

Here we present results of spectroscopic and photometric observations of V1929 Cyg in quiescence.
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Figure 1. The identification map of V1929 Cyg. North is up,
east is to the left
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\centerline{2}
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\centerline{\epsffile{4328-f2a.ps}}
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Figure 2. The spectra of the flare star V1929 Cyg in the blue (top)
        and red (bottom) 
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\centerline{3}
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Here we present results of spectroscopic and photometric observations of V1929 Cyg in quiescence.


The   spectroscopic observations  were made with the 6-m telescope of the
Special Astrophysical Observatory of the Russian  Academy of Sciences and
the  1000-channel   television   spectrophotometer  scanner  with  SP-124
spectrograph  (Drabek et al. 1985) during  the night of October 15, 1988.
The 600 lines/mm  diffraction  grating with effective resolution of about
5 \AA\ was used.  The  standardization of the spectra by observing a  well
known standard star following the work of Bares and Hayes (1984) was done.
A preliminary analysis of the  spectra (subtraction of the sky background,
correction   for   inhomogeneities   in   the   photocathode  sensitivity,
construction of dispersion curves,  and  linearization  of the  wavelength
scale  was carried out according to Somov (1985).  Further analysis of the
spectra -- correction for spectral sensitivity of the system,  smoothing by
means of  gaussians,  calculations  of physical parameters, was done using
the  Byurakan  Astronomical  Data  Analysing  system  (ADA -- Zaratsyan and
Maghakyan 1985).  The  observed  two  flare star spectra cover the visible
region of the spectrum 3500-6800 A. In Figure 2 the spectra of V1929 Cygni in
the blue and red spectral ranges are shown. 

The CCD photometric observations were made in the Rozhen Observatory of
the Institute  of Astronomy, Bulgarian Academy of Sciences with the 2-m
RCC telescope and ST-6 CCD camera on November 25, 1995. A series of two
120-sec exposures in B and V and 60-sec exposures in R  and I (Kron) was
obtained. The photometric reductions were made  with a software package
according to Georgiev et  al. (1994) with the WFPDB computer complex.
The magnitudes and colours of the star derived from the photometric BVRI
observations after the extinction corrections are: 
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\centerline{V = 15\fm 24; B$-$V = 0\fm 92; V$-$R = 0\fm 64;
V$-$I = 1\fm 28.}  
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According to this data V1929 Cyg  is one of the brightest flare stars in
the field of  NCG 7000 nebula.

V1929 Cyg is included neither in the list of IRAS point sources nor in
X-ray (ROSAT) catalogue. This fact could be due to the faintness of the
star and does not exclude the respective requirements for registration
in these catalogues.

The spectroscopic observations suggest  that the  star  is of spectral type
dK2-dK5  (with H$\alpha$-line in emission) having in  mind  the strong relation of
the TiO 5464 spectral  band with the spectral type of the stars of spectral
classes dK2-dM2 (Pritchet and van den Bergh 1977, Pettersen and Hawley 1987).

The  photometric  values  indicate  estimation of  the  spectral class dK2e
according to Zombeck's (1990) standard colours B$-$V = 0\fm 92,
V$-$R = 0\fm 74
and  V$-$I = 1\fm 22 for  stars  of  dK2  spectral type. Using the data for absolute
magnitudes and  colours  for dK2 stars  we obtained  a distance modulus of  (m$-$M)$_{\rm v}$ = 8\fm 64.
The  maximum  distance to V1929 Cyg would be 540 pc with the  assumption for
lack of interstellar absorption. As the average value of  A$_{\rm v}$  for some near
situated H$\alpha$-emission stars (like LkH$\alpha$ 189) is  estimated  by Cohen and Kuhi
(1979) to be  about 1$\magdot$0  we  derived about 33 pc for the distance to the flare star.  Taking  into  account that the distance to the NGC 7000
aggregate is  630 pc (Tsvetkov, 1976) we conclude that V1929 Cyg belongs
to the nearest part of this star-forming region.
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\centerline{4}
\vskip 2mm
This  work  was  partly  supported  by  grants F-340/93 and F-311/93 of the
National Science Fund of the Bulgarian Ministry  of  Education, Science and
Technology. 

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\beginauthors
\authorsrightcol
         Milcho TSVETKOV
         Evgeni SEMKOV
         Katya TSVETKOVA
         Institute of Astronomy
         Bulgarian Academy of Sciences
         E-mail: FSDB@bgcict.acad.bg
\vskip 2mm
         Valery HAMBARYAN
         Byurakan Observatory
         Armenian Academy of Sciences
         E-mail: Byurakan@pnas.sci.am
\endauthors

\references



Bares, J.V., Hayes, D.S.,  1984, { \it IRS Standard Manual, Kitt Peak National
Observatory}, 1984

Cohen, M., and Kuhi, L., 1979, { \it ApJ. SS.}, {\bf 41}, No.\,4, 743

Drabek, S.V., Kopylov, I.M., Somov, N.N., Somova, T.A., 1985, Astrophys. Issled.
({\it Izv. Spets. Astrofiz. Obs.}), {\bf 22}, 64

Georgiev, Ts., Getov, R., Semkov, E., Mutafov, A., Todorova, H., 1994, {\it The IAU
Working Group on Wide-Field Imaging}, Newsletter, {\bf 6}, 21

Kholopov, P.N., Samus, N.N., Kazarovets, E.V., Frolov, M.S., Kireeva, N.N., 1989,
{ \it IBVS}, No.\,3323

Pettersen, B.R., Hawley, S.L., 1987, {\it Publ. Inst. of Theor. Astroph.,
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Rosino, L., Tsvetkov, M., Tsvetkova, K., 1987, {\it IBVS}, No.\,2981

Somov, N. N., 1985, Astrophys. Issled. ({\it Izv. Spets. Astrofiz. Obs.}), {\bf 22}, 73

Tsvetkov, M.K., 1976, {\it PhD Thesis}, Yerevan University

Zaratsyan, S.V., Maghakyan, T.Yu., 1985, {\it Soobshch. Byurakan Obs.}, {\bf 57}, 80

Zombeck, M.V., 1990, {\it Handbook of  Space Astronomy and Astrophysics}, Cambridge, Uni. Press., Cambridge

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