COMMISSION 27 OF THE I. A. U.
         INFORMATION BULLETIN ON VARIABLE STARS
                     Number 1682

                                     Konkoly Observatory
                                     Budapest
                                     1979 October 5




           PHOTOELECTRIC ECLIPSE TIMINGS FOR
               AI Dra, SV Cam AND W UMa




Eclipses of these three binary stars were recorded with the 31 cm reflector
at NASA's Goddard Space Flight Center, Greenbelt, Maryland, during 1977 and
1978. The commercially manufactured photoelectric unit contains a 1P21 
photomultiplier tube, and B and V filters.
AI Dra was observed 18 times in each of the filters on May 27/28, 1977. 
Minimum light was found to occur at 02:58:15 UT in V, and 02:58:00 in B. These
times correspond to JD hel. 2443291.6253 in V, and 2443291.6251 in B.
SV Cam was observed 23 times in the V passband during its eclipse on April
29/30, 1977. The eclipse light curve appears asymmetrical, with the descending 
branch being steeper than the ascending branch. See Figure 1. This
asymmetry made determination of the time of minimum light slightly ambiguous.
Data points near the bottom of the eclipse light curve point to a minimum at
02:15:30 UT, while data points 0.4 magnitudes above minimum light result in a
time 7.5 minutes later. The average of these times corresponds to
JD hel. 2443263.5948.
W UMa was observed 12 times on March 5/6, 1978. minimum light is found to
have occurred at 01:42:15 UT (+- 1 minute), which corresponds to
JD hel. 2443573.5746.





                         A. D. MALLAMA
                         Computer Sciences Corporation
                         Silver Spring, Maryland 20910
                         8728 Colesville Road



                        [FIGURE 1]

                    Apr. 30, 1977 U.T.

 The V passband light curve of SV Cam. Notice that the brightness
 falls faster than it rises. Asymmetries have been seen in the
 light curve of this star for many years. The comparison star was
 SAO 001047.