COMMISSION 27 OF THE I. A. U.
         INFORMATION BULLETIN ON VARIABLE STARS
                   Number 1864

                                  Konkoly Observatory
                                  Budapest
                                  1980 November 12

                                  HU ISSN 0374-0676



        PERIOD OF SV CENTAURI STOPPED DECREASING



   Up to 1978 the period of SV Cen was decreasing very rapidly,
representing the highest rate of change of the period so far
known. Our recent observations between Jan. 1978 and July 1979
show that the period became constant giving new ephemeris

      T_min = HJD 2444061.0600 + 1.658500.E.

The pattern of period changes shows a cycle of about 32 years
but there is no strict periodicity and light-time interpretation 
is not feasible. Changes of both minima are simultaneous
and apsidal motion is also excluded.
   Observers using photoelectric photometers in the Southern
hemisphere are urged to pay attention to this very interesting
star. All photoelectric timing of minima has been done so far
in the UBV system and thus filters close to B and V should be
preferred for new measurements of minima.
   Modern photoelectric photometers allow the accuracy of the
determination of the time of minima up to 0.0001 day and a detailed 
study of period changes of SV Cen would require at least
3 observations of both minima per observing season (January to
August). Observers are reminded that the depth of minima shows
changes, too, and some observation during both maxima or a careful 
tie-in to the system of standard stars would greatly increase 
the information content of the measurements during minima.


       Z. KVIZ                       K.J. MURRAY
   Observatoire de Geneve           Broken Hill Division
   CH-1290 Sauverny               University of New South Wales
   Switzerland                      P.O. Box 334, Broken Hill,
   (On leave from The              2880, N.S.W., Australia
   University of New South
   Wales, Australia)