COMMISSION 27 OF THE I. A. U.
         INFORMATION BULLETIN ON VARIABLE STARS
                     Number 1916
    
                                 Konkoly Observatory
                                 Budapest
                                 1981 February 1

                                 HU ISSN 0374-0676


     PHOTOELECTRIC OBSERVATIONS AND NEW ELEMENTS FOR
                     KO AQUILAE


	The binary system KO Aquilae has been observed at the 
Bucharest Observatory in 1978-1979 with a 50-cm telescope. The 
photometer has an unrefrigerated EMI-6256B photomultiplier. In all
769 determinations in filter B and 748 in filter V have been 
obtained. The mean light curve in V is represented in Fig.1 (crosses). 
The phases were computed using the photometric elements
	Phase = (JD (hel) - 2441148.560) /2.86401d        (1)
from (1). In order to have the zero-phase in the middle of the
primary minimum, the mean curve was shifted by   subtracting
0.0075 from the phase.
	An approximate solution has been obtained using a model of
Horak type, the rectification of the curve outside the minima
has been computed with the Fourier development having the 
constants

            A_0 = 0.93417
            A_1 = 0.00454	  B_1 = -0.00549
            A_2 = 0.00900 	  B_2 = -0.00947

The limb darkening coefficients were adopted as u_h = 0.45 and
u_c = 0.60. The elements are given in Table I. the solution 
indicates an occultation at the primary minimum, the greater but
cooler star passing in front of the smaller and hotter star,
both eclipses being partial.

            		  Table I
		r_h = 0.1840   i^o = 86.76
		r_c = 0.2435   L_h = 0.8488
		k   = 0.7556   L_c = 0.1512              

The elements from Table I were improved using Wood's model. The
results are given in Table II and the theoretical light-curve
is represented in Fig.1.


                        [FIGURE 1]


From this figure one can see a good concordance between the
theoretical and observed light-curves.


                       	Table II

	Variable parameters     	Auxiliary parameters
		i^o = 82.33   	   	   a_h = 0.2148
		r_h = 0.2133   	   	   b_h = 0.2134               
		r_c = 0.2397   	   	   c_h = 0.2118
		k   = 1.1235  	   	   a_h = 0.2490
		T_c (eq)d = 5641   	   b_c = 0.3277
		W_c - 0.041        	   c_c = 0.2323
		q   = 0.453       	   T_h (pol)d = 9969
	Fixed parameters	   	   T_c (pol)d = 5762
		T_h (eq)d = 9900  	   L_h (norm) = 0.8724
		W_h = 0		  	   L_c (norm) = 0.1276
		beta_h = beta_c = 0.25     L_h (ap) = 0.1218
		u_h = 0.45    	   	   L_c (ap) = 0.0178
		u_c = 0.65       
		n   = 3.5
                       
  The complete solution, including observations with filter
B, will be published elsewhere.



              C. CRISTESCU, G. OPRESCU, M.D. SURAN
          Center for Astronomy and Space Sciences Bucharest



 Reference :

B.V. Kukarkin, P.N. Kholopov, Yu.N. Efremov, N.P. Kukarkina,
   N.E. Kurochkin, G.I. Medvedeva, N.B. Perova, I.P. Pskovskii,
   V.P. Fedorovich, M.S. Frolov - Second Supplement to the Third
   Edition of the General Catalogue of Variable Stars, Moscow,
   1974 [BIBCODE 1974sstt.book.....K ]