COMMISSION 27 OF THE I. A. U.
          INFORMATION BULLETIN ON VARIABLE STARS
                       Number 1095

                                  Konkoly Observatory
                                  Budapest
                                  1976 February 6




THE PHOTOMETRIC ACTIVITY OF o And FROM OCTOBER '75 TO JANUARY '76


    The shell star o And ejected a new shell in July 1975 (I.A.U.
Circ. No. 2802). From that time the star's spectrum has shown a 
remarkable activity. Following that, we decided to monitor 
photoelectrically this star.
    We observed it from October 1975 to January 1976 for 28 nights
in the U,B,V system. For 13 nights we made uninterrupted observations 
for several hours. The comparison star was 2 And.
    The star showed brightness variations on timescales of about
one day. The times of maxima and minima suggested us a probable
quasi-period of about 0.77 days, but the shape and the amplitude of
the light curves are different from cycle to cycle.
    The U, B, V curves have the same phase, but while in B and V
the largest amplitude is of about 0.09 mag., in U is about 0.03 mag.
larger. As example in Fig. from 1 to 6 are plotted the differences
of magnitudes (comparison star minus variable star) obtained in the
V light for 6 consecutive nights.
    It will be interesting to see if these variations are correlated 
with the spectral variations reported by Bolton and Gulliver
(I.A.U. Circ. No. 2899).
    Moreover o And displays light variations on longer timescales;
these are represented in Fig. 7, where the V observations are
plotted for all the nights (the dots represent the mean of the normals 
of the same night and the bar the range in magnitudes covered
by these when they are spanned over a time interval longer than one
hour). Also for these variations the behaviour in the three colours
is similar.

                       [FIGURE 1]
                       [FIGURE 2]
                       [FIGURE 3]
                       [FIGURE 4]
                       [FIGURE 5]
                       [FIGURE 6]
                       [FIGURE 7]

   Remarkable is the sudden decrease of about 0.1 mag. occurred
between Oct. 29 and Nov. 10, which apparently is not correlated
with spectral variations, since there are not communications 
concerning them. Likewise there are not remarkable light variations
connected with the spectral ones reported by Fracassini and 
Pasinetti (I.A.U.Circ. No. 2881).



                             M. BOSSI
                             G. GUERRERO
                             L. MANTEGAZZA
                        Osservatorio Astronomico
                        Via E. Bianchi 46
                        22055 Merate (Como) Italy