COMMISSION 27 OF THE I. A. U.
        INFORMATION BULLETIN ON VARIABLE STARS
                    Number 1932

                                  Konkoly Observatory
                                  Budapest
                                  1981 March 11

                                  HU ISSN 0374-0676


   RV CVn, A REMARKABLE SHORT PERIOD ECLIPSING BINARY


    RV CVn, a W UMa system placed in the sky not far from
the globular cluster M3, has been discovered by Larink (1921)
and discussed by means of photographic observations by Szeidl
(1973).
    This object has been observed with the double beam
photometer at the 1.06m telescope of Hoher List Observatory
on May 14 and 15, 1980 in B and V with integration times of
180 seconds for each measurement. Comparison star has been
BD+29d2444. The following minima times have been obtained:
       Min. II JD 2444374.5045  O-C=+0.0101d
       Min. I  JD 2444375.4430  O-C=+0.0051d
The O-C's have been computed according to the period given
by Szeidl:
       Min. I = 2424642.587 + 0.2695671d E
Considering the precision of the photographic minima 
determinations and a possible variability of the light curve shape
which can be expected for a short period W UMa system, the
period has remained constant to 10^-7 within the last 60
years.
With the light elements given above the B and V measurements
relative to BD+29d2444 have been plotted in Figs. 1 and 2.

                       [FIGURE 1]

           Fig. 1   B light curve of RV CVn


                       [FIGURE 2]

           Fig. 2   V light curve of RV CVn


  The light changes of RV CVn exceed 1.0m, which is quite rare
among W UMa systems. The difference of the minima depths
(~0.25m) is large for ordinary contact systems. At phase 0.35
in both nights a considerable "shoulder" has been found in
the light curve indicating some activity in the system. The
minima of RV CVn are apparently incomplete, but because of
the not very densely covered light curves a detailed analysis
has been omitted. With some reservation (e.g. is the contact
model applicable?) the light curve atlas by Anderson and Shu
(1979) indicates a mass ratio of 0.9 and an inclination of
more than 80d.
    These characteristics make RV CVn a favourable target
for further more detailed investigations.




                      M. HOFFMANN
                  Observatorium Hoher List
                  5568 Daun / Eifel, BRD




References:
Anderson, L., and Shu, F. H., 1979, Astrophys. J. Suppl. Ser.
         40, 667 [BIBCODE 1979ApJS...40..667A ]
Larink, J., 1921, Astron. Nachr. 214, 71 [BIBCODE 1921AN....214...71L ]
Szeidl, B., 1973, Budapest Mitt. No. 63  [BIBCODE 1973CoKon..63....1S ]
				[CoKon No. 63]