COMMISSION 27 OF THE I. A. U.
      INFORMATION BULLETIN ON VARIABLE STARS
                  Number 1524

                              Konkoly Observatory
                              Budapest
                              1978 December 28



               NOVA CYGNI 1978


    High speed (sampling time of 0.01 seconds) 
unfiltered photoelectric observations of Nova Cygni
1978 have been carried out on five nights (13, 14, 15,
20, 21) of September 1978, near its maximum brightness,
with the 1-meter Cassegrain telescope of the Astronomical 
Observatory of Trieste, equipped with a twin-beam
photoelectric photometer bearing EMI 62565A photomultipliers. 
The star BD+43d4012 (m_pg = 8.7) was adopted
as the comparison star.
    The nova showed flickering (up to frequencies of
about 5 Hz), characterized by a percent standard 
deviation ranging from 0.1 to 0.5, variable within every 
single night as well as from night to night.
    Power spectrum analysis revealed no stable periodic 
brightness variations. However, short living
quasi monochromatic oscillations have been observed.
On September 14 a ~15 Hz (starting time JD 2443766.4555)
and a ~81 Hz or higher order harmonic (starting time
JD 2443766.4862) oscillations lasting 100-:-200 seconds
were observed. On September 15 oscillations of ~0.19 Hz
(starting time JD 2443767.37265) monotonically 
decreasing in amplitude with time and lasting ~500 
seconds have also been detected.
    The figure is representative for the spectra of
the comparison star and of the nova during the night
of September 14. The time interval starts at JD 2443766.4555
and lasts for ~154 seconds. The range below ~5 Hz shows
clearly a power excess which can be attributed to the
flickering of the nova. The figure also evidences a

                  [FIGURE 1]

peak at ~15 Hz, which is well above the 99% upper
confidence level represented by the horizontal line,
whilst simultaneous spectrum of the comparison star
does not show evidence of lines at the same frequency.




               G. GIURICIN, F. MARDIROSSIAN, M. MEZZETTI,
               M. PUCILLO, P. SANTIN, G. SEDMAK
                Osservatorio Astronomico di Trieste
                        Italy