COMMISSION 27 OF THE I. A. U.
      INFORMATION BULLETIN ON VARIABLE STARS
                  Number 1622

                              Konkoly Observatory
                              Budapest
                              1979 June 12


                 TT Ari



   Fast (sampling time of 3 seconds) unfiltered
photoelectric observations of the nova-like variable
TT Ari (= BD+14d341) have been carried out on three
nights (22,23,24) of November 1978 with the 1-meter
Cassegrain telescope of the Astronomical Observatory      
of Trieste, equipped with a twin-beam computer controlled
photoelectric photometer bearing EMI 6256SA photomultipliers.
A finding chart for TT Ari, showing also the star we
have adopted as the comparison star, is given in Figure 1
(V= variable, C= comparison, a= BD+14d337, b= BD+14d339,
d= BD+14d342).
   Figures 2,3 and 4 show the lightcurve of TT Ari
obtained on November 22,23,24 respectively. The magnitude
differences are ordered as variable minus comparison. The
phases were calculated by using the value of the orbital
period P= 0.137551 (in days) given by Cowley et al. (1975);
the phase zero corresponds to JD 2443835.29585, JD
2443836.27660, JD 2443837.27205 for the three graphs
respectively. Strong flickering (up to 0.1 magnitudes)
is superimposed to the regular light variations associated
to the orbital period of TT Ari.
   Power spectral analysis revealed no stable periodic
brightness variations. However, a short living quasi
monochromatic oscillation (~0.026 Hz frequency) lasting
about 1500 seconds has been observed on November 22
(starting time JD 2443835.34419), as is shown in Figure
5a,b. The simultaneous spectrum of the comparison star
does not show evidence of similar lines at the same frequency.
Figure 5a,b is also representative for the power spectra of
the variable and of the comparison star during the night of
November 22. The range below ~0.02 Hz shows a power excess
which can be attributed to the flickering of the variable.


                     [FIGURE 1]
                     [FIGURE 2]
                     [FIGURE 3]
                     [FIGURE 4]
                     [FIGURE 5a]
                     [FIGURE 5b]



              F. MARDIROSSIAN, M. MEZZETTI, M. PUCILLO,
              P. SANTIN, G. SEDMAK, B. CESTER, G. GIURICIN

                 Osservatorio Astronomico di Trieste
                            Italy

Reference;

Cowley, A.P., Crampton, D., Hutchings, J.B., Marlborough, J.M.,
   Astrophys. J. 195, 413. [BIBCODE 1975ApJ...195..413C ]