COMMISSION 27 OF THE I.A.U.
               INFORMATION BULLETIN ON VARIABLE STARS
                           Number 2957

                                                    Konkoly Observatory
                                                    Budapest
                                                    21 November 1986

                                                    HU ISSN 0374 - 0676


        NEW EPHEMERIS AND LIGHT CURVE OF CF Pup

Eclipsing variable star CF Pup (CoD -49d 2046, S3270, CPD
-49d 856, discovery number 10.1942 Pup) was discovered by 
Hoffmeister (1943). So far the existence of the secondary minimum
had not been known. Because the duration of the flat part of
the primary minimum (totality) is comparable with the duration
of the night, the ephemeris based on Hoffmeister's 
photographic survey plates gave the wrong period.
   The new ephemeris (error estimates under resp. digits)

     T (min HJD) = 2445742.5663 + 7.649590d.E
                              2          5

is based on the observations in the Geneva photometric system
of Golay (1974, 1980) and Rufener (1964, 1981) performed
during the interval 1978 - 1985 with the 70 cm Swiss telescope
at La Silla Observatory, Chile. The photometer P7, described
by Burnet (1976) and by Burnet and Rufener (1979) was used for
all observations.
   As the two branches of the primary minimum were never
observed during the same night the ephemeris and its errors
were estimated from the geometrical fitting of individual
observations into one light curve. Accurate determination of
the times of minima would thus be a very suitable project for
a multisite photometric observing programme (Chile, South
Africa, Australia and/or New Zealand).
   For the filter V the following preliminary parameters have
been derived:
  Magnitude V = 10.15
  Duration of totality d = 0.03 P or 5.5 hours
  Duration of eclipse D = 0.12 P or 22 hours
  Depth of primary minimum 1.9 mag.
  Depth of secondary min. 0.08 mag.
  Ratio of stellar radii k = 0.6      (eclipse duration)


                          [FIGURE 1]

 Fig 1. Light curve of CF Puppis. Points represent individual
 observations in filter V in the GENEVA photometric system.
 Ordinates: V magnitudes. Abscissae: Phase.

                          [FIGURE 2]

 Fig. 2. Primary minimum of CF Puppis, detail from Fig. 1. Axes
 as in Fig. 1.



   The light-curve represented by individual measurements in
the colour V of the Geneva photometric system (which is the
same as V in the UBV system) is shown in Figs. 1. and 2. First
rough estimates of spectral types based on the colours of
Geneva photometry indicate F4 III and K2 III for primary and
secondary component respectively.
   These are only preliminary results. We publish them now
to make this information available to other observers, mainly
spectroscopists. After filling a few gaps in the light curve,
full details and the solution will be published elsewhere.
   One of the authors (Z.K.) wishes to express his gratitude
to the director of Geneva Observatory Prof. M. Golay for the
support during the stay at ESO, La Silla, and at the Geneva
Observatory. We acknowledge the excellent assistance of the
constructor of the photometer Dr. M. Burnet for keeping the P7
photometer in good condition and for some additional observations 
of this star.


               Z. KVIZ *, F. RUFENER
              Observatoire de Geneve
                 CH-1290 Sauverny
                   Switzerland

*  On leave from
   School of Physics, The University of New South Wales
   P.O.Box 1, KENSINGTON, 2033, N.S.W., AUSTRALIA



References:

Burnet M. 1976, Thesis No. 235, Ecole Polytechnique Federal
           de Lausanne. [BIBCODE 1976PhDT.......217B ]
Burnet M., Rufener F. 1979, Astron. Astrophys. 74, 54. [BIBCODE 1979A&A....74...54B ]
Golay M., 1974, Introduction to Astronomical Photometry, Reidel, Holland. [BIBCODE 1974ASSL...41.....G ]
Golay M., 1980, Vistas in Astronomy, 24, 141. [BIBCODE 1980VA.....24..141G ]
Hoffmeister C. 1943, Klein. Veroff. Berlin-Babelsberg No 27.
Rufener F., 1964, Publ. Obs. Geneve, ser. A, 66 (Thesis).
Rufener F., 1981, Astron. Astrophys. Suppl. Ser., 45, 207. [BIBCODE 1981A&AS...45..207R ]