COMMISSIONS 27 AND 42 OF THE IAU
             INFORMATION BULLETIN ON VARIABLE STARS
                         Number 3926

                                               Konkoly Observatory
                                               Budapest
                                               18 August 1993

                                               HU ISSN 0374 - 0676


            UBVR PHOTOMETRY OF THE ACTIVE ECLIPSING
                       BINARY DN CEPHEI


  Light variability of DN Cep (=SVS 894=VV 345; m=11.98-13.02pg; SP=B5) was 
described by Parenago (1938). Since, the only known observations of the binary have been
made photographically by Miller and Wachmann (1971). The authors determined the
light ephemeris of DN Cep. The secondary minimum was not seen on the curve. The
binary is situated in the region of the Cep OB1 association.
  In 1990/92 the observations of the DN Cep were made in UBVR filters with the 0.6
m telescope on Mt. Maidanak. The finding chart for the binary is shown in Figure 1,
taken from Miller and Wachmann's paper. The comparison star BD+55d 2706 (V=9.21m,
U-B=0.10m; B-V=0.19m; V-R=0.08m) and the check one (V=10.76m; U-B=+0.21m;
B-V=0.35m; V-R=0.33m) are denoted with s and c, respectively.
  The probable error of a single observation of the binary was determined to be 0.029m
in U; 0.017m in B; 0.019m in V and 0.017m in R. The numbers of the measured points are
188 in U; 300 in B; 307 in V and 299 in R filters, respectively.
  According to Miller and Wachmann's prediction the time of the obtained normal 
minimum is shifted by 0.9890p+-0.0003p and the improved ephemeris for the binary is
            
           MinI=JDH 2448953.078 + 3.3061560d x E
                        +-0.001 +-0.00000002
  
   The derived light curves for U, B, V, R colours are shown in Figure 2. From the Figure,
it can be seen that light curves show a considerable brightness scatter, both at and out
the minima. The clear-cut secondary minimum is seen only on the R-curve. We suppose
that the photometric activity of DN Cep may be understood in term of the early stellar
evolution. In this case the binary is to belong to Cep OB1 association. According to our
elementary distance estimation the binary can be related to the association. DN Cep is
expected to be an exceptionally interesting spectroscopic object.
  Finally, the basic characteristics of the light curves are given in Table 1.

             Table 1
-----------------------------------
          V      U-B    B-V    V-R
-----------------------------------
Max     11.98   -0.14   0.37   0.39
MinI    12.47   -0.11   0.41   0.37
MinII   12.05   -0.16   0.37   0.39
-----------------------------------

Note, that the amplitude in B colour is 0.5m whereas the photographic one was near
1.0m.

                               [FIGURE 1]

              Figure 1.   Finding chart for DN Cep.

                               [FIGURE 2]

              Figure 2.   The light curves of DN Cep.


M. M. ZAKIROV
A. A. AZIMOV                        V. F. UMAROV
Ulugh Beg Astronomical Institute    Nizamy Tashkent Pedagogic Institute
Astronomicheskaya, 33, Tashkent     Pedogocheskaya, 103, Tashkent
700052, Uzbekistan                  700064, Uzbekistan



References:
Miller W. J., Wachmann A. A.: 1971, Specola Astronomica Vatican Richerche Astron., 8,
  No. 12, 211 [BIBCODE 1971RA......8..211M ]
Parenago P. P.: 1938, Peremen. Zvezd., 5, No. 7, 206