COMMISSION 27 OF THE I.A.U.
               INFORMATION BULLETIN ON VARIABLE STARS
                            Number 1477

                                                      Konkoly Observatory
                                                      Budapest
                                                      1978 September 26


        PHOTOMETRIC BEHAVIOUR OF OMICRON ANDROMEDAE

The star Omicron And has variously been attributed different
kinds of light variation. Schmidt (1959) found the star to be an
eclipsing binary with a period of 1d.5998398, whereas, spectrographic 
observations by Galeotti and Pasinetti (1968) did not
support its eclipsing nature. Olsen (1972) suggests the star to
have Beta-Lyrae type variations with a period of 1d.0185, or 
alternatively that the light variations may be due to the intrinsic
variations of a single shell star. Bossi et al. (1976) correlate
the brightness variation, of the order of 0m.1, with a shell which
the star ejected in July 1975. They give no definite period. Recent
work by Fracassini and Pasinetti (1977) indicates that period of
shell phenomena may be about 23.5 years. Dworak (1976) has recorded 
a minimum of the star.
   The star was observed by us photoelectrically on the 38-cm
reflector of the Uttar Pradesh State Observatory on a total of
18 nights during the period October 1976 - December 1977, using
a refrigerated (-20dC) photomultiplier tube, the conventional U,
B and V filters of the Johnson and Morgan system, and standard
d.c. techniques. 2 And was used as a comparison star. The average
standard deviations of the comparison star on 9 random nights
are 0m.011, 0m.011 and 0m.010 in U, B and V filters, respectively.
   Our observations were planned on the basis of the following
two ephemeris:

(a) Primary minimum = JD 2436174.430 + 1d.5998398, Schmidt (1959);
(b) Primary minimum = JD 2439470.628 + 1d.0185, Olsen (1972).

                      [FIGURE 1]

Figure 1. Light curves of o And on an assumed period of 1.5998398d.
The differential magnitudes are in the sense variable minus comparison.

                      [FIGURE 2]

Figure 2. Light curves of o And on an assumed period of 1.0185d.
The differential magnitudes are in the sense variable minus comparison.


   The U, B, V light curves given in Figures 1 and 2, cover
almost the entire phases respectively on the above two suspected
periods with the +-2sigma error bars marked on them. The light curves
do not show eclipses or any kind of intrinsic variation with
periods of 1d.5998398 or 1d.0185. The light curves on individual
nights, especially those when primary or secondary minima were
predicted on the basis of either of the ephemerides, were also
carefully examined, but failed to provide any evidence of light
variation exceeding +-2sigma. Thus, while it appears certain that
the star is not a binary, the star did not show any kind of
activity during the period covered by our observations.
   The author is thankful to Dr. S.D. Sinvhal for helpful 
discussions and suggestions.


                            T.D. PADALIA

                            Uttar Pradesh State
                            Observatory
                            Manora Peak,
                            Naini Tal-263129,
                            India



References:

Bossi, M., Guerrero, G., Mantegazza, L., 1976, I.B.V.S. No. 1095
Dworak, T.Z., 1976, I.B.V.S. No. 1081
Fracassini, M., Pasinetti, L.E., 1977, I.B.V.S. No. 1341
Fracassini, M., Pasinetti, L.E., 1977, I.B.V.S. No. 1363
Galeotti, P., Pasinetti, L.E., 1968, I.B.V.S. No. 301
Olsen, E.H., 1972, Astron. Astrophys., 20, 167 [BIBCODE 1972A&A....20..167O ]
Schmidt, H., 1959, Zeitschrift fur Astrophysik, 48, 249 [BIBCODE 1959ZA.....48..249S ]