COMMISSION 27 OF THE I. A. U.
          INFORMATION BULLETIN ON VARIABLE STARS
                       Number 1067

                                    Konkoly Observatory
                                    Budapest
                                    1975 November 26





PHOTOMETRY OF THE ECLIPSING BINARY U OPHIUCHI AND OF NOVA CYGNI 1975


During May and June of 1972 and April and May of 1973 photoelectric 
observations of the eclipsing binary U Ophiuchi were made with
the 46-cm Cassegrain reflector of the Kutztown State College Observatory. 
The photomultiplier used was an unrefrigerated EMI 6256 SA(S-13
surface). The comparison star was HR 6412 (spectral type A0).
Four times of minimum light were obtained. Corrected for light
time, these are as follows:

JD 2441450.8271            I
       461.7332            II
       466.7653            II
       476.8293            II

The depth of the primary minimum was found to be 0.67m in visual
light and 0.71m in blue light. For the secondary minimum the depths
were 0.62m in V and 0.58m in B. The phase angle of external tangency
was found to be 30.2deg for both eclipses.
At maximum light U Ophiuchi is 0.32m brighter than HR 6412 in V
and 0.47m brighter in B. Using the values of V = 6.16 and B-V = +0.22
obtained by Cousins for HR 6412 one obtains V = 5.84 and B-V = +0.07
for U Ophiuchi at maximum light. As the spectral types of the components 
of U Ophiuchi are estimated as B4 and B5, it appears that the
system is substantially reddened.
All observations of U Ophiuchi included the 12th magnitude visual 
companion, which is about 20" distant from the eclipsing pair. The
contribution of this star to the light of the system, however, is 
negligible.
During the autumn of 1975 photographs were taken of Nova Cygni
and the surrounding field in Cygnus. A 135 mm lens at f/2.8 was used.
The exposures ranged from 2 min. to 30 min., and the film used was
Plus-X Pan. The times and estimated photographic magnitudes are as
follows: 

     UT                                   UT
1975 Sep.10.2  6.4                   1975 Oct. 4.1   8.0
         14.2  6.7                            15.1   8.4
         29.1  7.5                            23.0   8.6


Kutztown State College
Kutztown, Penna., 19530, U.S.A.     

                                               G. A. BECKER
                                               C. R. CHAMBLISS
                                               A. KIASAT