COMMISSION 27 OF THE I. A. U.
        INFORMATION BULLETIN ON VARIABLE STARS
                    Number 1785

                               Konkoly Observatory
                               Budapest
                               1980 May 14


              ON THE PERIODICITY OF SS 433


The inspection of roughly 400 Sonneberg plates, 220 of which are of remarkable
quality, showed that no obvious periodicity in the range of several days to
several tens of days is present in our estimates of this object (SS=Stephenson,
Sanduleak, ApJ Supp. 33, p. 549). The plates had been taken with the
astrographs 40/160 cm, 40/190 cm and 17/120 cm, mostly during the years 1961
and 1962, but also scattered over the whole time since 1928. Neither a period
around 165 days nor a persistent one around 6.5 (or 13) days (these values are
often quoted in literature) seem detectable. The brightness variations could
be considered as wave-shaped with changing cycle lengths of 5 to 15 days,
superposed by shorter-termed fluctuations. The reality of the latter cannot,
however, be proved in all cases because of the faintness of the star near the
plate limit. The observed photographic amplitude is 1.7 mag (15.0m to
16.7m), most estimates ranging between 15.8m and 16.4m (referred to Mt.
Wilson SA 111).


W. WENZEL
Sternwarte Sonneberg
Zentralinstitut fur Astrophysik
Akademie der Wissenschaften der DDR