COMMISSIONS 27 AND 42 OF THE IAU
           INFORMATION BULLETIN ON VARIABLE STARS
                       Number 3903

                                         Konkoly Observatory
                                         Budapest
                                         6 July 1993

                                         HU ISSN 0374 - 0676



        TIMES OF MINIMUM OF ECLIPSING BINARIES WITH
                  NON-CIRCULAR ORBITS


  During April and May 1993, we enjoyed an observational stay at the
Rosemary Hill Observatory, operated by the Department of Astronomy of the
University of Florida, Gainesville, U.S.A. One of the observing programs
consisted in the timing of minima of eclipsing binaries with non-circular orbits,
the results of which are reported here.
  The minimum times given in Table I were determined photoelectrically
employing the 76 cm (30 inch) reflector of the Rosemary Hill Observatory,
located near the town of Bronson in north-central Florida. This telescope is
equipped with a standard one-channel photometer at its Cassegrain focus. An
EMI6256S photomultiplier operated in the DC-mode and cooled with dry ice
yields good photometric quality down to about 13th magnitude. The set of filters
has been carefully chosen in order to reproduce the standard Johnson UBV
system (Diethelm, 1993).
  The times of minimum were deduced from differential photometry using
comparison stars taken from the previous work on these variables. None of the
comparison stars showed variability exceeding the accuracy of the photometric
system. A field diaphragm of 32 arcseconds diameter was used throughout.



                       Table I
Times of minimum of eclipsing binaries with non-circular orbits

---------------------------------------------------------------------
Star    Type     O        e.e.       O-C       n    Remarks
               JD_hel              (GCVS 85)
---------------------------------------------------------------------
BW Boo   s  49099.73:   +/-0.05    -0.16       32   V, remark overleaf
EK Cep   p  49115.8081  +/-0.0003  +0.0058     36   V
V478 Cyg p  49124.7720  +/-0.0030  +0.0197     32   V
V959 Cyg p  49124.8123  +/-0.0015  -0.0340     14   V
V577 Oph s  49105.7808  +/-0.0020  +0.4884     50   see Diethelm (1993)
EQ Vul   s  49113.82:   +/-0.02    -0.04       38   V, remark overleaf
---------------------------------------------------------------------

   Remarks to Table I:
   BW Boo: The displaced secondary reported by Kurpinska (1975) is
confirmed. Due to the small amplitude (about 0.025 mag in V) and the very slow
variation, only an approximate time of minimum can be given.
   EQ Vul: The night of JD 2449113 was not of photometric quality. The
lightcurve therefore shows considerable scatter due to the changing sky
conditions. Furthermore, the descending branch is very poorly covered. The
time given in Table I is only an upper limit to the actual time of minimum.

   Acknowledgements: We would like to thank the staff of the Department of
Astronomy of the University of Florida for their hospitality and for the generous
allocation of observing time at Rosemary Hill Observatory. The continuing
technical assistance by J. Baker is especially acknowledged. This research is
supported by a grant from the Emilia Guggenheim-Schnurr foundation.


                           R. Diethelm
                           BBSAG
                           Rennweg 1
                           CH-4118 Rodersdorf
                           Switzerland




References:
Diethelm, R: 1993, I.B.V.S. No. 3894
Kurpinska, M: 1975, I.B.V.S. No. 1007