COMMISSION 27 OF THE I. A. U.
         INFORMATION BULLETIN ON VARIABLE STARS
                     Number 2116

                                Konkoly Observatory
                                Budapest
                                1982 March 23

                                HU ISSN 0374-0676





                                        
   PERIODIC LIGHT VARIATIONS OF THE DWARF NOVA CN ORIONIS *





    Photometric observations of CN Ori have been performed from
1981 December 3 to 18. The system decreased from an eruption
and after a few days at minimum started for an other outburst.
During all nights a periodic humplike feature was detected.
Fig. 1 shows a condensed light curve.

                       [FIGURE 1]

 * Based on observations collected at the European Southern 
  Observatory.

Using the nights with HJD-2444900 + 44 to 54 one obtains the
following ephemeris for the light maximum:

         HJD_max  = 2444951.6150 + .16308 * E
                             +-5      +-4

There are considerable variations in shape and phase of the
hump which are stronger during the brighter stages and prevent
a more precise period determination. The hump amplitude varies
not more than about 30% around the mean except during the first
night when the hump is very weak. The almost periodic change in
hump intensity, with a cycle of approx. 4 days, resembles the
beat phenomenon of SU UMa stars. CN Ori is classified as of
Z Cam type however (Bateson 1979).
No pronounced increase in hump amplitude before or during rise
to maximum occurs and therefore an explanation of this outburst
in terms of increased mass transfer through the hot spot 
producing stream seems impossible.





                R. SCHOEMBS
                Universitats-Sternwarte
                Scheinerstr. 1
                D-8000 Munchen 80
                Germany





Reference:

Bateson, F., M., Publ. of VSS RAS NZ No. 7, 28, 1979