COMMISSION 27 OF THE I. A. U.
         INFORMATION BULLETIN ON VARIABLE STARS
                     Number 1642

                                   Konkoly Observatory
                                   Budapest
                                   1979 July 17



          THE SECONDARY PERIOD OF RZ CEPHEI



    We have analized the 20 light maxima obtained by Todoran
during 1972-1973 (I.B.V.S. No.915, 1974) and 2 maxima observed
in the same period by Cester and Todoran (Mem.SAIt, 47, 217).
    At first we have derived the following elements valid from
	J.D.2441475 to J.D.2442006:
	Max.hel = 2441475.378+ 0.30868218d*E                (1)
    Table I contains the 22 maxima and the O-C values derived
from the ephemeris (1).
    Based on an harmonic analysis we have derived the secondary 
period of the star: P_b = 96.8 P_0 = 29.88d.
    In Figure 1 the values of O-C are plotted against the phase
of the secondary period computed by the formula:
	Lowest Maximum = 2441464.147+ 29.88d*N              (2)
    The phases of the light maxima performed with the elements
(2) are given in third column of Table I.


                         [FIGURE 1]

             Table I
Max. hel.
2440000             O-C   psi

1475.380          +0.002d 0.38
1519.519           0.000  0.85
1546.372          -0.003  0.75
1559.339           0.000  0.19
1605.335           0.002  0.73
1605.640          -0.002  0.74
1608.420           0.000  0.83
1897.350           0.004  0.50
1902.286           0.001  0.66
1902.592          -0.002  0.67
1903.520           0.000  0.70
1904.445          -0.001  0.74
1907.530          -0.003  0.84
1942.410          -0.004  0.01
1946.425          -0.002  0.14
1963.402          -0.002  0.71
1975.439          -0.004  0.11
1984.396           0.001  0.41
1985.325           0.004  0.44
1991.190           0.004  0.64
1991.495           0.001  0.65
2006.310          -0.001  0.14





                          FEDERICO FICARROTTA

                          CLAUDIO ROMOLI

                          Observatory of Monte Zufolone
                          Technical Direction
                          Via Garibaldi 3
                          I-20013 Magenta (Milano)
                          Italy