COMMISSION 27 OF THE I. A. U.
         INFORMATION BULLETIN ON VARIABLE STARS
                      NUMBER 869

                                Konkoly Observatory
                                Budapest
                                1974 February 12


             ON THE PERIOD OF U CEPHEI


   In a recent issue of this Bulletin Hall (IBVS No.847,1973)
pointed out that U Cephei would have suffered a very large increase 
of its period, Delta P/P = 6x10^-4 if one of our observations made
in August 1969 (Bakos and Tremko, Bull.Astr.Inst.Czech. 24, 298,
1973) is correct. He also showed that with the exclusion of
this particular observation all the other photoelectric epochs
of minima satisfy a quadratic formula for the ephemeris of U Cep.
As an explanation of the discrepancy, among other possibilities,
it was suggested that the epoch of our observation could have
been in error by 0.01 days.
   In order to satisfy ourselves that no error has crept in
our observations we re-checked every step of the reduction procedure 
starting from the original strip-chart records. We also
made a new determination of the epoch of minimum of August 6/7,
1969 and of its internal mean error. The result is the following:

   Primary minimum = J.D. hel. 2440440.51946 +- 0.00006,

the same as originally published.
   It is, therefore, our conclusion that the observed increase
of the period of U Cep at that particular time is real and we
also do agree with the suggestion made by Batten (private 
communication) that the increase in the period is related to the
distortion of the light curve at the time in question and to
his observation of the emission in the spectrum of the star
just a few weeks after our observation.


G.A. BAKOS *  and J. TREMKO

Skalnate Pleso Observatory
Tatranska Lomnica
Czechoslovakia

* Permanent address: University of Waterloo Observatory,
Waterloo, Ontario, Canada.