COMMISSION 27 OF THE I. A. U.
        INFORMATION BULLETIN ON VARIABLE STARS
                    Number 1371

                                  Konkoly Observatory
                                  Budapest
                                  1977 December 19



      ON TWO SEMIREGULAR VARIABLE STARS RS SAGITTAE

                 AND RZ VULPECULAE




   Observations of these variable stars have been obtained by
me from plates of Moscow and Simeis Collections. Most observations 
were published (1).
   Both stars appear to show properties similar to those of
RV Tau (b)-type variables; i.e. fast periodic variations 
superimposed upon slow fluctuations of mean light. The slow variations
of mean light of RS Sge (see above) are given in Fig. 1. The 
amplitudes are rather large. Besides, they are variable too. If
these variations are cyclic, the cycles may exceed 6000 days.
Smooth variation of amplitude in RZ Vul is of particular interest. 
It is a phenomenon never observed in RV Tau(b)-type stars.
The elements of slow variations are given in Table 1.
   Fast fluctuations are superimposed upon slow ones, the 
amplitudes of which reaches 1.5 mag. The elements of fast 
variations are summarized in Table 2. The period of RZ Vul has been
noticed to vary throughout the observations, so one has to use
two systems of elements.
   In Fig. 2 and 3 the fragments of the light curve are given
which characterize the fast fluctuation in the light of RZ Vul.





                          V. TSESSEVICH
                          Odessa Astronomical
                          Observatory


Reference:

(1) V.P. Tsessevich and B.A. Dragomoretska, "RW Aurigae stars.
             Photographic Observations of Brightness",
             Kiev, 1973, Naukova Dumka


                 Table 1
         Elements of slow variations
  Star    Interval JD     Max.   Min.        Period
 RS Sge 2436000-2443000 2435999 2436596       1124d
 RZ Vul 2436000-2443000 2437807 2438458       1196

                           Table 2
 Elements of fast fluctuations superposed on slow ones
 Star      Interval JD       Max.        Min.      Period
RS Sge   2436000-2443000   2436057.2  2436077.7   41.1975
RZ Vul   2436074-2440815   2436434.4  2436416.1   39.8415
   "     2441429-2442961   2441454.1  2441433.9   40.2156


                       [FIGURE 1]
                       [FIGURE 2]
                       [FIGURE 3]