COMMISSION 27 OF THE I. A. U.
         INFORMATION BULLETIN ON VARIABLE STARS
                     Number 2415

                                        Konkoly Observatory
                                        Budapest
                                        18 October 1983

                                        HU ISSN 0374-0676



  NEW DATA ABOUT THE APSIDAL MOTION IN THE SYSTEM OF RU MONOCEROTIS




Judging from the observations since 1973 there is now a substantial body
of evidence which shows that the apsidal motion of the RU Mon system is slowing
down. Instead of the previous value Delta omega/Delta E = 0.01285d it has now become
0.0114d. At the beginning of 1982 the value of omega (the longitude of periastron)
became 90d, the secondary minimum now precedes the middle of two consecutive
primary minima.
At the same time the value of the orbital period P is now lengthening:

   E<3400               P = 3.584679d
3400<E<6100                      639
6100<E<6700                      586
6900<E<7900                      680

For the next 5-7 years (as well as for the previous ones) the moments of
minima may be forecast with the following linear formulae:

Min I Hel.= JD 2441743.1947+ 3.584749d E'
Min II Hel.= JD 2441741.575+ 3.584567d E'
E' = E - 6930

Three recent photoelectric epochs of minima and their representation with
these formulae are as follows:

Min I Hel. JD 2444528.544   E'= 777,         O-C = -0.001d
Min I Hel. JD 2445288.5117      989,               +0.0002
MinII hel. JD 2445376.326      1014,                0.000

  The paper is due be published elsewhere in detail.




                 D.Ya. MARTYNOV
               Sternberg Astronomical
               Institute, Moscow
               U.S.S.R.