COMMISSION 27 OF THE I. A. U.
           INFORMATION BULLETIN ON VARIABLE STARS
                        NUMBER 855

                            	 	Konkoly Observatory
                             		Budapest
                             		1973 December 31


    A NEWLY DISCOVERED W URSAE MAJORIS SYSTEM: ADS 1693 A


    ADS 1693 A (2h05m9, +44d12'; 1900) is the brightest component
of a multiple star system (see Figure I). In 1908 Espin mentioned
that either the A or the B component was a variable. In 1971 and
1972 F. Josties and J. Christy obtained multi-exposure-astrometric
plates of this system at the U.S. Naval Observatory in Washington,
D.C. Visual estimates from these plates by K.A.A. Strand showed the
A component to be variable with a brightness change of 0.6 magnitudes 
in thirty minutes.
    In October and November of 1973 250 sets of UBV observations
were obtained of ADS 1693 A on five nights with the 102 cm reflector
at the Flagstaff Station of the U.S. Naval Observatory. The information 
obtained from these data is tabulated in this report.
    A composite light curve of observations obtained on two consecutive 
nights is presented in Figure II. Close examination of the
individual light curves for each night show variations in the maxima 
and minima. This is typical of W Ursae Majoris systems.
    Times of minima were determined by the Hertzsprung method and
are listed in Table I. All the minima were combined by the method of
least squares and produced the following light elements:

       T_I = 244 1976.69136 +/- 0.30573d n
        
From the residuals in Table I it is obvious that the period is not
constant over the observed interval (another characteristic of W Ursae
Majoris systems). A second set of light elements was determined using
only the primary eclipses:

       T_II = 244 1976.69458 +/- 0.30501d n
        
    The magnitudes and colors of the variable at maxima and minima
are given in Table II. The B component was used as the comparison star
and the C and D components were used as check stars (see Table III).
    The spectral types listed in Tables II and III were inferred
from the colors (assuming no reddening) and were based upon the work
of M.P. Fitzgerald (Astron. and Astrophys. 1970, 4, 234). The spectral
types listed in Table II are further evidence that ADS 1693 A is a
W Ursae Majoris system.


                      Table I
                  Times of Minima
JD 0                                       T_I       T_II
244 0000.0000+    Eclipse          n       O-C        O-C
    1976.8470       sec           0.5    +0.0028d   -0.0001d
    1977.7605       sec           3.5    -0.0009    -0.0016
    1977.9146       pri           4.0    +0.0003     0.0000
    1992.8599       pri          53.0    -0.0352     0.0000
    1993.9981       sec          56.5    +0.0330    +0.0707

                      Table II
             Magnitudes and Colors of ADS 1693 A

Phase             V           	 B-V            U-B       sp
0.00            11.61 		+0.82          +0.35      K0
0.25            10.88 		+0.74          +0.24      G7
0.50            11.58 		+0.80          +0.34      K0
0.75            10.83 		+0.77          +0.27      G7

                      Table III
    Magnitudes and Colors of Comparison and Check Stars

Star              V 		 B-V            U-B        sp
ADS 1693 B      11.13 		+0.70          +0.18       G5
ADS 1693 C      11.91 		+1.10          +0.89       K4
ADS 1693 D      12.65 		+0.72          +0.30       G7


                     [FIGURE 1]

                     [FIGURE 2]



                             R.L. WALKER
                          Flagstaff Station
                          U.S. Naval Observatory
                          Flagstaff, Arizona, U.S.A.