COMMISSION 27 OF THE I. A. U.
	 INFORMATION BULLETIN ON VARIABLE STARS
		     Number 2639


				    Konkoly Observatory
				    Budapest
				    10 December 1984

				    HU ISSN 0374 - 0676


 	       B AND V PHOTOMETRY OF VZ Psc
  Publications of Rothney Astrophysical Observatory, Series B, No. 11


  An observing history of the 0.261 day system VZ Psc can be found in Poretti
(1984). The system's short period and late spectral type (K2-K5) make it an
important late type contact system.

  The system was observed on 4 nights between JD 2444808 and 2444813 with
the #4 0.4-m telescope at KPNO using a dry ice cooled GaAs detector,
BD + 4d5016 was selected as the comparison star. Each star was measured in
the sequence VBBV, followed by a single V and B measurement of the sky. The
comparison star was observed after every two variable star measurements.
BD + 4d5009 was observed at least once each night as a check on the non-
variability of the comparison star.
  Phases were computed using the ephemeris of Eggen (1967). The light curve
is shown in Figure 1. Calculations of times of minimum light were performed
with the RAO's PHIMIN code which uses essentially the method of Kwee and
van Woerden (1956)The resulting phases of minimum light are:
0.5226p+- .0032 in B, and 0.509p+- .0112 in B, giving a weighted mean value of
0.5216p+- .0034. Based on the light curve presented here, the minimum 
observed by Poretti appears to be the secondary, as he suspected
  Fourier analysis of the light curves showed that they could be accurately
represented by a five term fit of the form:

	 l  = A_0 + A_1cosTheta + A_2cosTheta + B_1sinTheta + B_2sinTheta

  The coefficients of the V and B full light curves, normalized to the
weighted mean of the maxima are given in Table I, where the uncertainties
in units of the last place are given in parentheses. The error of the fit,
in magnitudes, is given in the last column.
  The results of analyses on the full light curve, the maxima outside
+-0.1 of the minima, and the maxima outside +-0.15 of the minima are not
greatly different. This is what is to be expected for the light curve of an
ellipsoidal variable.

                           [FIGURE 1]

		    Table I
      VZ Psc Fourier Coefficients - July 1981 Full Light Curves
---------------------------------------------------------------
      A_0	A_1	  A1	   A_2	     A_2       e
---------------------------------------------------------------
 V    0.918(1) -0.030(2) -0.006(2) -0.083(2) +0.006(2) +-0.016
 B    0.912(2) -0.041(3) -0.004(3) -0.091(3) +0.010(3) +-0.029
---------------------------------------------------------------




  The system displays a marginal O'Connell effect (Davidge and Milone 1984) of
0.016 +- 0.012 in V and 0.039 +- 0.011 in B, based on means of the data in each
maximum.
  A detailed discussion of this and more recent photometry will appear 
elsewhere, and Hrivnak and Milone are preparing a radial velocity study for 
publication.





		       T. J. DAVIDGE
		       E. F. MILONE
		       Rothney Astrophysical Observatory
		       Physics Department
		       The University of Calgary
		       Calgary, Alberta, Canada
		       T2N 1N4





References :

Davidge, T.J., Milone, E.F.; Ap. J. Supp. 55, 571, 1984. [BIBCODE 1984ApJS...55..571D ]
Eggen, O.J., Ap. J., 150, L111, 1967. [BIBCODE 1967ApJ...150L.111E ]
Kwee, K.K., van Woerden, H., B.A.N., 12,327, 1956. [BIBCODE 1956BAN....12..327K ]
Poretti, E., IBVS No. 2487, 1984.