COMMISSION 27 OF THE I. A. U.
        INFORMATION BULLETIN ON VARIABLE STARS
                     NUMBER 382

                                Konkoly Observatory
                                Budapest
                                1969 September 30


           UBV PHOTOMETRY OF GAMMA PEGASI

      Gamma Pegasi (HR 39, MK standard of spectral type
B2 IV; standard star of UBVRI photometry, a Beta Cephei-type
variable) was observed by the author on two nights in October
1965 with a photoelectric photometer mounted in the
Cassegrain focus of the Lowell Observatory's 21-inch
reflecting telescope. An EMI 6256 S photomultiplier tube
with a set of standard UBV filters and usual D. C. equipment
were used. Star 34 Piscium (HR 26, spectral type B8 V)
served as only comparison star. Its magnitude and colour
indices on the UBV system were determined by comparison
with standard stars on six nights in October and November
1965. The results are: V = 5.535m +/- 0.0013m, B-V = -0.069m +/- 0.0015m,
and U-B = -0.194m +/- 0.0032m (mean errors).
      The V, B and U magnitudes of the variable star
are plotted against phase in Fig. 1.  Phases were computed
from elements of maximum radial velocity of Sandberg and
McNamara (P.A.S.P. 72, 508. 1960), and then increased by
0.25. It may be seen from Fig.1 that light ranges in V, B,
and U are equal to 0.017m+/-0.002m, 0.018m+/-0.001m and 0.027m+/-0.001m,
respectively. The U-B colour index of the star is smallest
around maximum light, while the B-V colour index is constant
within 0.003m. In addition to the overall variability in the
spectroscopic period of 3h38m, the B magnitude of Gamma
Pegasi undergoes regular fluctuations with amplitude of
0.005m in a short period equal to about 44m, i.e. one fifth
of the longer period. The phenomenon is less pronounced in
the V and U magnitudes, probably because of observational
errors. Local maxima of the light-curves in V, B, and U are
shifted relatively to one another.
      The mean V magnitude of Gamma Pegasi is equal to
2.823m +/- 0.002m, and its mean B V and U-B colour indices are
equal to -0.227m +/- 0.003m and -0.870m +/- 0.004m, respectively.
The mean U B colour index determined by comparing the
variable star alone with standards of the UBV system (on
the same nights when the differential observations were
made) turned out to be -0.864m.

                      [FIGURE 1]

Fig. 1 The V, B and U magnitudes of Gamma Pegasi plotted against
phase. Circles denote observations taken on October 30,
         points those made on October 31, 1965.



September 20, 1969


                        MIKOLAJ JERZYKIEWICZ
                    Wroclaw University Observatory