COMMISSION 27 OF THE I. A. U.
        INFORMATION BULLETIN ON VARIABLE STARS
                     NUMBER 173



                                     Konkoly Observatory
                                     Budapest
                                     29 December 1966




          REMARK CONCERNING THE AMPLITUDE
                OF RU CAM DURING 1965


      The strong decrease of the amplitude of RU Cam, discovered
by DEMERS and FERNIE (ApJ 144, p. 440), can be traced continuously
on plates of the - Sonneberg Sky Patrol. In particular the outstanding
behaviour, mentioned by the above quoted authors, of four U-observations 
on J.D. 243 8884 ... 8922 might be explained as follows.

      At Sonneberg the observations of each three months were
combined into one mean light curve. These curves show that in the
second quarter of 1964 the amplitude of RU Cam in the photographic
region (blue-sensitve emulsion ORWO ZU 2) was still 0.65m but 
decreased during the third quarter to 0.m15. Also in the following time
(1964/4 and 1965/1) the brightness showed a fluctuation of this amount
only.
      But in the second quarter of 1965 the amplitude became 
remarkably larger, 0.25m photographically (see figure). It was then that
the above mentioned four isolated photoelectric U-values of strong
deviation appeared: One must take into account that in 1960 the period
of RU Cam shortened to 22.073d, so that for the time of decreasing
amplitude the following elements can be given:


              Min. = 243 7114. 0 + 22.073d . E.

                           [FIGURE 1]

      According to this formula we have for the quoted U-values the
phases 0.66; 0.94, 0.98 and 0.93 (+ integers). Thus the observations
show in the U-region a minimum of brightness with a range of about
0.m8 in accordance with the instantaneous elements.

      From 1965/3 onward the variation of brightness flattened
again, being not larger than about 0.1m photographically till the end of
1966.
      Our results confirm the conclusion from other photoelectric
material that the decrease of the amplitude in the V-region is 
considerably stronger than in U, and mpg takes a medium position.
Furthermore the remark by DEMERS and FERNIE (1. c.) on the 
constancy of the mean intensity might be applied in general only to the
bolometric magnitude.
      A detailed description of the Sonneberg observations will be
given by HUTH in a forthcoming number of MVS.



                                                 H. HUTH
  
                                                 W. WENZEL
              Sternwarte Sonneberg
                      der
      Deutschen Akademie der Wissenschaften