COMMISSION 27 OF THE I. A. U.
       INFORMATION BULLETIN ON VARIABLE STARS
                    NUMBER 453

                              Konkoly Observatory
                              Budapest
                              1970 July 20

      PHOTOELECTRIC TIMES OF MINIMA OF RR CENTAURI

      The eclipsing binary RR Centauri = HD 124689 has
been observed photoelectrically at the Bosque Alegre
Station of the Cordoba Observatory. The observations were
taken at the 154 cm reflecting telescope with a RCA lP28
photomultiplier plus a GG14 Schott glass filter. The photoelectric 
signals were amplified through a Field Effect
Transistor amplifier (Sistero, 1970).
      The primary minimum was observed on June 24 about
U.T. 2 20m. From 69 peV observations the time of primary
minimum was derived:

        Min. I. = J.D. hel 2440761.6003
                              +- 0.0028    m. e.

and from 80 observations on June 25 the time of secondary
minimum was obtained:

        Min.II. = J.D. hel 2440762.5158
                              +- 0.0014    m.e.

      From the observed times of minima new light
elements were derived by comparisons with the elements in
the finding list given by Koch, Sobieski and Wood (1963).
The Knipe's elements given there, compared with the present
observations, permit an improved re-determination of the
period: P = 0d60569131 +- 0d00000058 m.e. Table I lists
the minima with the given weights and the cycles and
residuals from the linear light elements:

     Min.I = J.D. hel 2438946.9535 +- 0.60569131. E
                              0020 +-  .00000058 m.e.

     We are continuing work on this star.

     

                       TABLE I.

Min        J.D. hel        E       W      O-C
I       2437132.3014      -2996    4    -0.001d
I       2440761.6003      +2996    1    -0.004
II      2440762.5158      +2997.5  3    +0.003


                        
                        
                        R.F. SISTERO

                        M.E. CASTORE de SISTERO
                        Cordoba Observatory
                        Laprida 854, Cordoba
                        Argentina


References

Koch, R.H., Sobieski, S. and Wood, F.B. 1963, Pub. of
         the Univ. of Pennsylvania, Astr. Series Vol.IX.

Sistero, R.F., 1970, in preparation.