COMMISSION 27 OF THE I. A. U.
           INFORMATION BULLETIN ON VARIABLE STARS
                       Number 3159

                                      Konkoly Observatory
                                      Budapest
                                      18 March 1988

                                      HU ISSN 0374-0676


            LIGHT CURVE VARIATIONS OF SV CAMELOPARDALIS

  The light variability of SV Cam was firstly discovered by Guthnick (1929).
Wood (1946) reported an asymmetry in the system's light curve; according to
his analysis, the primary component is close to its Roche limit. Hence, the
observed period and light curve variations were considered reasonable due to
the instability of the primary near its limiting surface. The long-term variation
in the O-C curve of SV Cam has been subjected to studies by Sommer (1956),
Frieboes-Conde and Herczeg (1973), Hilditch et al. (1979), and Cellino et al.
(1985) who reported different light-time periods ranging from 57.5 to 74.7
years. Hall (1976) included the system into his list of short-period RS
CVn-type binaries. Meanwhile, Hilditch et al. (1979) attributed the out-of-eclipse
changes to a BY Dra-type variability of the secondary component. An extensive
observational material was presented by Patkos (1982). Patkos (1981) also gave
a discussion on the locations of some flare-like events he observed.
  We observed the system in B and V filters with the 48 cm Cassegrain reflector
of Ege University Observatory on three nights in October 1985. An uncooled
EMI 9781 A was the photomultiplier employed. BD +82 168 has been monitored as
comparison star. The differential magnitudes in the sense variable minus
comparison were corrected for atmospheric extinction and the times of the
individual observations were reduced to the Sun's centre. The corrected 
magnitudes were plotted against the phases which were computed by using the light
elements given by Cellino et al. (1985) as

       Min.I=J.D.(Hel.) 2426949.3939+0.59307133d E     .
                                +/-8       +/-3

  In Figures 1 and 2, the present photoelectric light curves of the system
are presented along with the unpublished photoelectric ones obtained by Celikezer
(1976) in our observatory during the observing season of 1975, to demonstrate
in what manner the system's light changes. What immediately can be deduced from
Figures 1 and 2 when they are compared with Figure 1 of Hilditch et al. (1979)
is the existence of a completely different behaviour of the individual light
curves obtained in different epochs.


                               [FIGURE 1]

 Figure 1. B light curves of SV Cam. Dots are Celikezer's observations
           obtained in 1975. Plus signs refer to the present observations.

                               [FIGURE 2]

 Figure 2. V light curves of SV Cam. Signs are the same as in Figure 1.

                               [FIGURE 3]

 Figure 3. B-V colour variation of SV Cam in 1985 with respect to the
           comparison star.


  According to the observations of Hilditch et al. (1979), all light curves
coincide to within +/-0.01 mag at mid-secondary eclipse, which normally urged
them to conclude that the light curve variations are due to intrinsic variability
of the cooler component which is invisible around phase 0.5. Contrary
to this situation, the light curves obtained in our observatory both by us and
Celikezer (1976) do not have indications of any coincidence at mid-secondary
eclipse. As it is seen from Figures 1 and 2, the light levels of Celikezer's
and the present light curves differ from each other not only at the secondary
minimum, but also for the most parts. It is worth noting that Celikezer's
observations obtained on ten nights between March-December 1975 are well
separated from night to night.
  As reported by Hilditch et al. (1979), only 7 percent of the secondary
component is visible at phase 0.5, that is, the secondary eclipse is practically
total. When this fact is considered together with the varying light levels seen
in secondary minimum (see Figures 1 and 2) it seems very unlikely for the secondary
component "alone" to take the whole responsibility of the system's lightcurve 
variations.
  Getting rid of making any comment for the time being here on the potential
contribution(s) of the secondary component on the light-curve changes, the
photoelectric observations presented in this paper evidently suggest that the
primary component should have a significant role on this event. This is also
consistent with the conclusions of Cellino et al. (1985) and Patkos (1981).
  Figure 3 shows the colour variations of SV Cam with respect to the comparison
star.
  An extensive work is being carried out on the present observations of SV Cam
and the results will be published in the near future.


     M.C. AKAN, Z. TUNCA, C. IBANOGLU, S. EVREN, and V. KESKIN

           Ege University Observatory
           Bornova, Izmir, Turkey

References:

Celikezer, N.: 1976, Master's thesis, Ege University, Bornova, Izmir.
Cellino, A., Scaltriti, F., Busso, M.: 1985, Astron. Astrophys., 144, 315. [BIBCODE 1985A&A...144..315C ]
Frieboes-Conde, H., Herczeg, T.: 1973, Astron. Astrophys. Suppl., 12, 1. [BIBCODE 1973A&AS...12....1F ]
Guthnick, P.: 1929, Astron. Nachr., 235, 83. [BIBCODE 1929AN....235...83G ]
Hall, D.S.: 1976, in "Multiple Periodic Variable Stars," Proc. IAU Coll. No. 29,
      ed. W.S. Fitch, Reidel, Dordrecht, Vol. 1, p. 287. [BIBCODE 1976ASSL...60..287H ]
Hilditch, R.W., Harland, D.M., McLean, B.J.: 1979, Monthly Notices Roy. Astron.
      Soc., 187, 797. [BIBCODE 1979MNRAS.187..797H ]
Patkos, L.: 1981, Astrophysical Letters, 22, 1. [BIBCODE 1981ApL....22....1P ]
Patkos, L.: 1982, Commun. Konkoly Obs. Hung. Acad. Sci. Budapest, No. 80. [BIBCODE 1982CoKon..80....1P ]
									[CoKon No. 80]
Sommer, R.: 1956, Astron. Nachr., 283, 155. [BIBCODE 1956AN....283..155S ]
Wood, F.B.: 1946, Contr. Princeton Obs., No. 21, p. 40. [BIBCODE 1946CoPri..21....1W ]