COMMISSION 27 OF THE I. A. U.
           INFORMATION BULLETIN ON VARIABLE STARS
                        Number 2771


                                          Konkoly Observatory
                                          Budapest
                                          7 August 1985

                                          HU ISSN 0374 - 0676



                 THE J LIGHT CURVE OF CG CYGNI



  We present the J light curve of the eclipsing binary CG Cygni (P=0.63d)
obtained with the 1.5 m infrared flux collector at the Observatorio del Teide,
Tenerife, using a cooled InSb detector. The data were obtained during 4 out
of 5 consecutive nights in September 1984. The comparison star was BD+34deg 4216
and the principal standard star was BS8430.
  In Figure 1 is the J light curve of CG Cygni with the differential magnitude
plotted against the phase, calculated using the ephemeris of Milone and Ziebarth
(1974)

          JD(phase=0) = 2439425.1221 + 0.6311410d E.


                              [FIGURE 1]

                Figure 1: J light curve of CG Cygni.




  The J light curve shows the asymmetry of the minima that has been previously 
observed in optical curves of CG Cygni (Milone et al. 1979; Jassur, 1980)
and some other short period RS CVn-type binaries. Figure 1 also shows that
the minima have advanced in phase by about 2.5% since 1966, confirming 
conclusively the progressive change first noted by Milone et al.
A fuller account of this work is being prepared for publication.





  J.J. FUENSALIDA, M. J. AREVALO                D. K. BEDFORD
  Instituto de Astrofisica de Canarias          Dept. of Space Research
  La Laguna                                     University of Birmingham
  Tenerife, Spain                               Birmingham, U.K.





References :

Jassur, D.M.Z.: 1980, Astrophys. Space Sci. 67, 19. [BIBCODE 1980Ap&SS..67...19J ]
Milone, E.F., Ziebarth, K.E.: 1974, Pub. Astron. Soc. Pacific 86, 684. [BIBCODE 1974PASP...86..684M ]
Milone, E.F., Castle, K.G., Robb, R.M., Swadron, D., Burke, E.W., Hall, D.S.,
     Michlovic, J.E., Zissell, R.E.: 1979, Astron. J. 84, 417. [BIBCODE 1979AJ.....84..417M ]