COMMISSION 27 OF THE I. A. U.
        INFORMATION BULLETIN ON VARIABLE STARS
                     NUMBER 503

                              Konkoly Observatory
                              Budapest
                              1971 January 4

   A LIKELY 15.5 YEAR APSIDAL MOTION PERIOD IN HS Her

     The purpose of this note is to draw attention to
HS Her: an eclipsing binary which seems to have an apsidal
motion period of only 15.5 years. A complete discussion
will be published later. Times of primary (and secondary)
minimum observed in the next very few years could confirm
this value. A 15.5 year apsidal motion period would be the
shortest known, the shortest until now being the 25-year
period of GL Carinae.
     HS Her is ideal for observing. It is bright (V=8.6m
at maximum); the orbital period is short and convenient
(P = 1.64d); the eclipses are brief (D = 5h); and both minima
are reasonably deep (DeltaV pri = 0.50m and DeltaV sec = 0.15m),
     All of the data available at this time can be
satisfied only by the following ephemeris for primary minimum, 
with the sine term; attributed to apsidal motion:

Hel.JD = 2 437 854.194+1.6374333d E+0.017d sin (E/3450-360d)

These data include spectroscopic orbital elements (Cesco
and Sahade 1944) and times of minimum, both published
(Martynov 1940, 1951; Hall 1967) and unpublished (Hall and
Hubbard 1970; Atkins and Devinney 1970; and Martynov 1970).
	The above ephemeris predicts there should be no
displacement of secondary minimum with respect to primary
in the simmer of 1971, when HS Her next becomes observable.
But after that, for the next 7 or 8 years, secondary minimum 
should occur later than 0.50p.


                        DOUGLAS S. HALL
                       Dyer Observatory
                      Vanderbilt University
                    Nashville, Tennessee 37203
                            U.S.A.
References

Atkins, H. and Devinney, E.J., Jr. 1970. private 
   communication.
Cesco, C. and Sahade, J. 1945, Ap.J. 101, 114. [BIBCODE 1945ApJ...101..114C ]
Hall, D.S. 1967, P.A.S.P. 79, 444. [BIBCODE 1967PASP...79..630H ]
Hall, D.S. and Hubbard, G.S. 1970. in preparation.
Martynov, D.Ja. 1940, Bull Astr.Obs. V.P. Engel'gardta,
  No. 18, 38,
Martynov, D.Ja. 1951, Izv.Astr.Obs.V.P. Engel'gardta,
  No. 26, 47.
Martynov, D.Ja. 1970, private communication.






                   [From IBVS 523]


Correction to IBVS No 503 (HS Her):


       The last term in the equation should read:

               +0.017d sin (360d E/3450)