COMMISSION 27 OF THE I. A. U.
         INFORMATION BULLETIN ON VARIABLE STARS
                      NUMBER 555

                                     Konkoly Observatory
                                     Budapest
                                     1971 May 26


      PHOTOELECTRIC LIGHT CURVES OF PV CASSIOPEIAE

      We have observed the eclipsing binary PV Cas (=BV72=BD+58d2554)
during eleven nights between June 7 and September 1, 1970 with the 48 cm 
Cassegrain telescope of the Ege University Observatory. In these observations an
unrefrigerated RCA 1P 21 photomultiplier was used with B and V of the UBV
system.
      Actually the light curves of this star were obtained by GEYER (1)
eleven years ago. But in these light curves the secondary minimum was not seen
and he proposed that this star had no secondary minimum.
      Then POHL (2) has determined new light elements for this star as
follow: 

      C: Min JD 2428 796.8142+1.75047346d . E                      (1)

The period obtained by Pohl is nearly double of that given by Geyer, and it is in
good agreement with our observations. Table 1 shows the observed times of
primary minima, O-C values against the elements given by Pohl, and the names
of the observers. (Ib = C. Ibanoglu, Kt = M. Kurutac, Al= A. Caliskan, Od=O
Demircan, Hl= H. Sengonca, Rk=R. Akinci, Dn=H. Donmez, Me=M. Meier, Pl=E.
Pohl, Yy=Y. Yildiz.)




             Table I
------------------------------------
        O           O-C    Observers
------------------------------------
2 440 129.381  pe  +0.002    Ib
      227.4061 "   +0.0002   Ib/Kt
      416.456  "   -0.001    Ib/Al
      479.475  "   +0.001    Ib/Od
      817.314  "   -0.001    Ib/Hl
      824.317  "    0.000    Ib/Rk
      831.3168 "   -0.0024   Ib/Dn
      852.321  "   -0.004    Me/Pl
-------------------------------------



Pohl has also proposed the following equation for the secondary minimum:

                MinI-MinII=0.516. P                 (2)

But the results of our observations are not in full conformity with this equation.



We obtained from our light curves:

                MinI- MinII=0.522. P                (3)

Table II gives the observed times of the secondary minima, O-C values 
according to (2) and (3) respectively. The O-C residuals are decreasing.




                      Table II
-------------------------------------------------
            O       O-C_I     O-C_II  Observers
-------------------------------------------------
     2436851.5916 +0.0018   +0.0123   Geyer
         895.3523 +0.0006   +0.0111   Geyer
      440515.320  -0.011     0.000    Ib
         767.3886 -0.0103   +0.0002   Ib
         830.4071 -0.0089   +0.0016   Ib/Yy
-------------------------------------------------



       The light curves of PV Cas are shown in Figures 1 and 2, where the
magnitude differences variable minus comparison star BD+58d2562 are plotted
against phase using Pohl's elements. The star varies about 0.6m in both blue
and yellow. It is seen that both light curves and minima are similar. Probably
the components are of the same spectral type and their diameters are 
approximately equal. The secondary minimum is displaced from 0.5P. Hence
PV Cas has an eccentric orbit. We need more observations to proof whether
the decrease of the O-C values in Table II is caused by apsidal motion.


May 20, 1971
                               CAFER IBANOGLU
                               Ege University Observatory
                               P. K. 21
                               Bornova-Izmir, TURKEY


References:                          
(1.) GEYER, E.H. : Zeitschrift fur Astrophysik 51, 79, (1960) [BIBCODE 1961ZA.....51...79G ]
(2.) POHL, E. : Information Bulletin on Variable Stars. 386, (1969)


                             [FIGURE 1]
                             [FIGURE 2]