COMMISSION 27 OF THE I. A. U.
	      INFORMATION BULLETIN ON VARIABLE STARS
  			  Number 3444

			  		    Konkoly Observatory
					    Budapest
					    12 March 1990

					    HU ISSN 0374 - 0676


  	          Pulsation period of CY Cnc

  Breger (1970) in a study of Praesepe cluster (NGC 2632) observed 
CY Cnc (KW 114, HD 73345, m_v=8.14, F0V) during 2.2
hours and remarks "small variability possible". Later Jackish (1972)
classified it as probable delta Scuti type variable, he estimated a period
around 2-3 hours.

  The observing run was carried out during one night in December,
1989, with the 1.5m spanish telescope in the Calar Alto 
Observatory (Almeria, Spain). The variable and both comparison
stars (C1=HD 73294 and C2=HD 73430) were measured in uvby
filters. The light curve in filter b is shown in figure 1 as magnitude
differences (CY Cnc-C1) in instrumental system, the solid line was
calculated from the obtained frequency


                          [FIGURE 1]


    The Fourier analysis carried out for our data (Lopes de Coca
et al., 1984), showed a dominant frequency at 30.8 c/d and an
amplitude of 0.005m.

    For the photometric calibration (Lopez de Coca et al., 1990),
we have used the indices given by Hauck and Mermilliod (1985)
and we obtained the following physical parameters for this star:
Mbol=2.06; log Te=3.902 and log g=4.074. With these values, we
can calculate the pulsational constant Q with the classical Petersen
and Jorgensen (1972) formula, thus, Q=0.016 that should correspond 
to the third overtone.

    Therefore, we can conclude that CY Cnc can be considered as
a normal delta Scuti variable, although more observations are needed.


    ACKNOWLEDGMENTS: This research was supported by the
Direccion General de Investigacion Cientifica y Tecnica (DGICT)
under project PB0310.


                      A. ROLLAND
                      J.M. GARCIA-PELAYO
                      E. RODRIGUEZ
                      P. LOPEZ DE COCA


            Instituto de Astrofisica de Andalucia.
                 Apdo 2144, Granada, Spain.


REFERENCES:

Breger, M. 1970, Astrophys. J. 162, 597. [BIBCODE 1970ApJ...162..597B ]
Hauck, B. and Mermilliod, M. 1985, Astron. Astrophys. Suppl. Series.
   60, 61. [BIBCODE 1985A&AS...60...61H ]
Jackisch, G. 1972, Astron. Nachr. 294, 1. [BIBCODE 1972AN....294....1J ]
Lopes de Coca, P., Garrido, R. and Rolland, A. 1984, Astron. Astrophys. 
   Suppl. Series. 58, 441. [BIBCODE 1984A&AS...58..441L ]
Lopez de Coca, P., Rolland, A., Rodriguez, E. and Garrido, R. 1990,
   Astron. Astrophys. Suppl. Series. (in press). [BIBCODE 1990A&AS...83...51L ]
Petersen, J.O. and Jorgensen, H.E. 1972, Astron. Astrophys. 17, 367. [BIBCODE 1972A&A....17..367P ]