COMMISSION 27 OF THE I. A. U.
          INFORMATION BULLETIN ON VARIABLE STARS
                      Number 915

                                  Konkoly Observatory
                                  Budapest
                                  1974 August 8


                  MAXIMA OF RZ CEPHEI

    During 1972-1973 photoelectric observations of the RRc star
RZ Cephei were carried out at the Cluj Astronomical Observatory. The
preliminary results are given.
    The observations were made in V light with a 50 cm Newton
reflector, a photometer employing an unrefrigerated 1P21 photomultiplier 
tube and a Corning 3384 filter.
    The light curve shows a broad maximum with some fine structure,
i.e., a pre-maximum hump which may be variable in shape.
    Having in view the shape of the light curve during its maximum,
Pogson's method was used in order to derive the time of maxima.
    In order to have a general picture of the period variation we
continued Geyer's (Z.f.Ap. 44, 98, 1958) O-C diagram and for this 
purpose (O-C)_1's were computed by using the linear elements

    Max.hel. = J.D. 2410000.000 + 0d.308668.E

Comparing our results with figure 2 of Geyer's paper we conclude that
the period has been lengthening. For the last ten years we have derived 
the following elements

    Max.hel. = J.D. 2441475.373 + 0d.308686.E

which were used to compute the differences O-C_2.

    The numbers of the observations used are given under n.

Max.hel.   n      E_1     O-C         E_2           O-C_2
2440000
1475.380   24   101970   +0d.504        0         +0d.007
1519.519   24   102113     .504       143         + .004
1546.372   15   102200     .502       230         + .001
1605.335   24   102391     .510       421         + .005
1605.640    9   102392     .506       422         + .002
1608.420   40   102401     .508       431         + .003
1897.350   20   103337     .525      1367         + .003
1902.286   13   103353     .522      1383           .000
1902.592   10   103354     .520      1384         - .002
1903.520   29   103357     .522      1387           .000
1904.445   30   103360     .521      1390         - .002
1907.530   22   103370     .519      1400         - .003
1942.410   41   103483     .519      1513         - .005
1963.402   40   103551     .522      1581         - .004
1975.439   19   103590     .521      1620         - .005
1984.396   30   103619     .527      1649           .000
1985.325    7   103622     .530      1652         + .003
1991.190   14   103641     .530      1671         + .003
1991.495   21   103642     .526      1672         - .001
2006.310   25   103690     .525      1720         - .003


                                             IOAN TODORAN
                                   Astronomical Observatory Cluj,
                                                Rumania