COMMISSION 27 OF THE I.A.U.
                 INFORMATION BULLETIN ON VARIABLE STARS
                             Number 3217

                                                         Konkoly Observatory
                                                         Budapest
                                                         26 July 1988

                                                         HU ISSN 0374 - 0676


          ECLIPSING BINARY SIGNATURES IN ZETA CAPRICORNI

Zeta Capricorni (zeta Cap=HD 204075) was shown to be a Barium line spectroscopic 
binary, possessing strong BaII line by Bohm-Vitense (1980), Smith et al.
(1980), Culiver (1981) and Smith and Lambert (1984). Zeta Cap is shown to have
a white dwarf companion by Bohm-Vitense (1980), which is much fainter than
Zeta Cap. Photoelectric observations of zeta Cap are hardly available in the
literature except for the color indices (B-V=1.00m and U-B=0.59m, Sp.=G5) given by Eggen (1972).
   Zeta Cap was chosen as standard star during the observations of the programme
star delta Cap, and was observed on the 38 cm reflector of the Uttar Pradesh
State Observatory employing thermoelectrically cooled (-20 C) 1P21
photomultiplier, conventional UBV filters, and d.c.  techniques. A total of
three nights of observations were obtained between JD 2444163 to JD 2444908,
using gamma Cap (=HD 206088) as comparison and epsilon Cap (=HD 205637) as
check star. The apparent graphical errors of U, B and V observations are on the
average +/-0.06m, +/-0.02m and +/-0.02m respectively. The differential 
magnitude and
the differential colour curves are shown in Figure 1, wherein the large scatter
in U observations is apparent and, as such, U observations may not be taken for
granted.
   The colour indices nearly at the mid-points of these light curves are
given as follows:

J.D.(Hel.)    B-V   U-B
 2444163     1.07m  0.71m
 2444554     0.31   0.94
 2444908     0.94   0.85

   If the two eclipses that are thought to be present in Figure 1 on JD 2444163
and JD 2444908, separated by nearly two pears are real, it may be possible
that zeta Cap is a long period (may be few years, at least 4 years or more)
eclipsing binary, which is not improbable in the light of the suggestion by
Culiver (1981) that the spectroscopic period is 2300d. Also, McLaure et al.
(1979) thought zeta Cap to be existing in a binary system with a long period,


                               [FIGURE 1]


80 to 500 days at least. Although, the present observations are not sufficient
to establish its eclipsing binary nature, yet they do point to the possibility
of its being an eclipsing binary.


                      R.K. SRIVASTAVA

               Uttar Pradesh State Observatory,
               Manora Peak, Nainital - 263 129,
                         India



References:

Bohm-Vitense, E., 1980. Astrophys, J., 239. L79-L83. [BIBCODE 1980ApJ...239L..79B ]
Culiver, R.B., 1981, Bull. Am. Astron. Soc., 13, No, 4, 973. [BIBCODE 1981BAAS...13..873C ]
Eggen, O.J., 1972, Mon. Not. R. Astron. Soc., 159, 403. [BIBCODE 1972MNRAS.159..403E ]
Mc Laure, R.D., Fletcher, J.M., and Nemec, J.M., 1979, preprint.
Smith, V.V., and Lambert, D.L., 1984, Publ.Astron.Soc. Pacific, 96, 226. [BIBCODE 1984PASP...96..226S ]
Smith, V.V., Sneden, C., and Pilachowski, C.A., 1980, Publ. Astron.
   Soc. Pacific, 92, 809. [BIBCODE 1980PASP...92..809S ]