COMMISSION 27 OF THE I. A. U.
         INFORMATION BULLETIN ON VARIABLE STARS
                      NUMBER 128


                                        Konkoly Observatory
                                        Budapest
                                        22 March 1966


                 NOTE ON THE AMPLITUDE
                 OF THE CEPHEID RU CAM


       Alerted by a preprint of an article by Fernie and Demers on
RU Cam, which will be published as a letter to the Astrophysical
Journal, in which they suggested the stopping of the star's light
variation, the author has made a quick reduction of his own 
observations of this cepheid. The photo-electric observations were made
with the 10-inch refractor of the Leiden Observatory in combination
with a Corning 3384 filter with an effective wavelength of 5390 A. 
Observations were made from September 1965 until February 1966.
       My results do not suggest that the pulsation has actually come
to an end, but they confirm Fernie an Demers' result that the range
has become very small. It is seen from the diagram that the range is
about 0.13mag. The observations indicate that the period has remained
practically unchanged.

                         [FIGURE 1]

      A correction for differential extinction has not been applied,
because it does not exceed 0.01 magnitude. The error of the points,
which are a mean of four individual observations, is about 0.01mag. The
phase was calculated with a period of 22.134 day with the formula phi = 1/p
(J. D. - 2430000). As comparison star BD+70deg447 was used. The table
gives the heliocentric Julian date, the magnitude differences and the
phases.

 Hel. J. D.     m      phi
2439018.519   -.489   .451
    019.562   -.518   .498
    024.490   -.581   .721
    025.543   -.589   .768
    026.550   -.571   .814
    030.512   -.496   .993
    031.561   -.468   .040
    053.444   -.485   .029
    054.494   -.467   .076
    056.651   -.454   .174
    059.525   -.460   .304
    079.363   -.422   .200
    080.389   -.449   .246
    178.498   -.558   .679




Leiden Observatory
4 March 1966



                               W. WAMSTEKER