COMMISSION 27 OF THE I. A. U.
           INFORMATION BULLETIN ON VARIABLE STARS
                        Number 3007


                                            Konkoly Observatory
                                            Budapest
                                            6 April 1987

                                            HU ISSN 0374-0676


     PHOTOELECTRIC OBSERVATIONS OF TT ARIETIS ON 1/2 OCTOBER 1986

  Coordinated observations of this accreting white dwarf in a low-mass binary,
simultaneously in the X-ray and the optical region, were carried out by 
numerous authors during summer and autumn 1985 (Wenzel et al. 1986, 1987).
One year later, during the night of 1986 Oct. 1/2, as checked the behaviour
of the object by photoelectrical observations with the Piszkesteto 50 cm
telescope in Hungary. Star c (after Wenzel et al. 1986) served as comparison
star. The measurements were made in the blue sensitivity region b. For the
transformation into international B magnitudes the empirical formula

B = b + (sec z - 0.7297) / 13.3061

was used.

The resulting light curve (Fig. 1) shows the following.


                           [FIGURE 1]


1. During that night the star was in its "active" state (high brightness).

2. The photometric period of about 3.2 hours can clearly be recognized from
   the space of time between the two observed maxima, but these maxima are
   not in phase with the maxima "C" computed from the photometric elements
   given by Wenzel et al. (1986).

3. There are quasi-periodic fluctuations of the kind described in Wenzel
   et al. (1986, 1987) and Semeniuk et al. (1986). The cycle length seems to
   be not constant, but varying between 14 and 21 minutes.
4. During the observation time there occured an unusually deep dip in 
   brightness down to 11.5m.

   The numerical data of these observations will be published in "Mitt.
   Veranderl. Sterne", Sonneberg.


                             S. ROSSIGER
                     Zentralinstitut für Astrophysik
                        Sternwarte Sonneberg
                             Sonneberg
                             DDR-6400


References:

Semeniuk, I., Schwarzenberg-Czerny, A., Duerbeck, H., Hoffmann, M., 1986,
    Inf. Bull. Var. Stars No. 2899
Wenzel, W., Hudec, R., et al., 1986, Preprint
Wenzel, W., Hudec, R., et al., 1987, in preparation