COMMISSION 27 OF THE I. A. U.
       INFORMATION BULLETIN ON VARIABLE STARS
                   NUMBER 756

                                  Konkoly Observatory
                                  Budapest
                                  1973 January 17


         28-SECOND OSCILLATIONS IN VW Hyi


    The southern hemisphere dwarf nova VW Hyi underwent
an outburst starting on December 10 and returned to normal
light by December 28. A fairly detailed photometric coverage
of this outburst has been obtained with the 40 inch reflector 
of the Sutherland Station of the South African Astronomical 
Observatory, using high speed photometric equipment similar 
to that described by Nather and Warner (M.N.R.A.S. 152,
209, 1971). During outbursts of the dwarf novae Z Cam, CN Ori
and AH Her, Warner and Robinson (Nature 239, 2, 1972) found
oscillations with periods near 17, 24 and 31 secs respectively. 
All the data collected during the recent outburst of VW Hyi
will be subjected to a periodogram analysis to search for 
similar periodic oscillations, but we feel it may be of interest
to other observers to announce that on 25th December, when VW Hyi
was rapidly declining but was still about 2 magnitudes above
normal (minimum) light, brightness variations having a period
of 28.15 secs and a peak-to-peak amplitude of about 5 percent
were clearly seen throughout a 4 hour observing run. The beginning 
of this run is illustrated in the accompanying light curve.
    This is the first time that rapid oscillations in the light
curve of a dwarf nova have been large enough to see without the
aid of a periodogram analysis. The appearance of the light curve
is very similar to that shown by the wellknown 71 sec oscillations
in DQ Her.



Department of Astronomy,   BRIAN WARNER
University of Cape Town.   JOHN M. HARWOOD



                      [FIGURE 1]

   Vertical scale is total number of counts per 4-sec integration.