COMMISSION 27 OF THE I. A. U.
         INFORMATION BULLETIN ON VARIABLE STARS
                   Number 2175

                               Konkoly Observatory
                               Budapest
                               1982 July 12

                               HU ISSN 0374-0676





        HIGH SPEED PHOTOMETRY OF V794 AQUILAE



     X-ray and optical observations of V794 Aql were recently
reported by Szkody et al. (1981), which show that this star is
a member of the cataclysmic variable class. Their photometric
observations show that V794 Aql is variable by up to 0.5 mag
on an hourly timescale, with greater variations on a timescale
of days. This note draws attention to the tremendous activity
that occurs on a timescale of tens of seconds.
     Observations were made on the nights of 30 and 31 May,
1982, with the high speed photometer attached to the 40 inch
reflector at the Sutherland site of the South African Astronomical 
Observatory. Integrations in white light of 5 secs and 10
secs respectively were used. The lengths of observation were
2.0 hours and 3.2 hours respectively.
     The light curve (corrected for atmospheric extinction)
obtained on 30 May is shown in Figure 1. The mean light level
corresponds approximately to V = 14.6, so V794 Aql was in a
 "high state" at the time of observation.
     It can be seen from Figure 1. that V794 Aql is one of the
Most active of cataclysmic variables. Brightness Variations of
up to 0.5 mag occur or a timescale of minutes with smaller flares
on timescales of tens of seconds. 
     The light curve for 31 May was similar to that seen in
Figure 1. Power spectra of each of the light curves do not
show any significant periodic components. Nor is there any sign
of orbital modulation of the light curve that would indicate
a period less than 3 hours.

                       [FIGURE 1]

Light curve of V794 Aql at 5 sec time resolutions. The ordinate 
is counts per second. Abscissa marks are at intervals of
0.0025 day (216 secs) starting in the top left hand corner at
JD_Hel 2445120.5925, and continuing along the lower axis for the
bottom curve.





                               BRIAN WARNER

                           Department of Astronomy
                           University of Cape Town


Reference:
P. Szkody, L. Crosa, G.D. Bothun, R.A. Downes and R.A. Schommer,
  Astrophys. J. Letts., 249, L61, 1981. [BIBCODE 1981ApJ...249L..61S ]