COMMISSION 27 OF THE I. A. U.
            INFORMATION BULLETIN ON VARIABLE STARS
                        Number 3552

                                               Konkoly Observatory
                                               Budapest
                                               7 January 1991

                                               HU ISSN 0374 - 0676


   TIMES OF MINIMUM LIGHT FOR 17 ECLIPSES OF 7 DETACHED BINARIES

   We report here on the continuation of a program of observing
eclipsing binary systems suggested by Herczeg (1980), as systems
that may show unusual period changes, or systems which have not
been observed frequently enough to confirm period changes.
   The observations were made with the 46-cm reflector at
Appalachian State University's Dark Sky Observatory. The
photometer is a Kitt Peak National Observatory single-channel
design employing a thermoelectrically cooled EMI 9865QB
photomultiplier tube with matching UBVR filters. An Astronomical
Time Mechanisms Model 240V amplifier provides a voltage-to-
frequency output that is integrated by a microcomputer.
   The observations for a given eclipse were made through one
filter only, to maximize the number of data points. The
observations have not been transformed to the Johnson system,
since they were only intended for timing analysis. The
observations are available from the IAU Archives, file number
213.
   The times of minimum light and standard errors given in
Table I were calculated using the method of Kwee and van Woerden
(1956), using a program written by Ghedini (1982). This
algorithm has been shown by Caton (1989) to give the most
accurate estimation of time of conjunction for asymmetric or
distorted light curves.
    We gratefully acknowledge the partial support provided by
NSF Grant AST-8705770.


                        Table I

System    Type of      Heliocentric JD    Comparison    Filter
          Eclipse      (-2400000)             Star

RT And    Primary      47082.75694        BD +52d3384     V
                         +-0.00061
RX Ari    Primary      47121.58061        BD +21d0311     V
                         +-0.00023
          Secondary    47208.57714        "   "   "       V
                         +-0.00096
          Primary      47473.71053        "   "   "       V
                         +-0.00028
WW Aur    Primary      46840.73088        BD +32d1320     R
                         +-0.00016
AW Cam    Secondary    47543.75928        BD +69d0390     R
                         +-0.00021
          Primary      47596.59558        "   "   "       R
                         +-0.00076
          Primary      46836.81707        "   "   "       R
                         +-0.00031
          Primary      46877.70027        "   "   "       R
                         +-0.00014
          Primary      46894.67054        "   "   "       R
                         +-0.00037
          Primary      47184.69471        "   "   "       V
                         +-0.00050
RX Her    Secondary    46926.76777        BD +11d3481     V
                         +-0.00047
TX Her    Primary      46877.84439        BD +42d2822     R
                         +-0.00037
          Primary      47324.82068        "   "   "       V
                         +-0.00013
          Primary      46974.65447        "   "   "       R
                         +-0.00031
CM Lac    Primary      47073.72594        BD +43d4110     V
                         +-0.00034
          Primary      47508.59652        "   "   "       V
                         +-0.00048


               DANIEL B. CATON, WANDA C. BURNS, R. LEE HAWKINS

               Dark Sky Observatory
               Department of Physics and Astronomy
               Appalachian State University
               Boone, North Carolina 28608 U.S.A.



References:

Caton, D.B. (1989), Bull. A.A.S. 21, No. 1, 714. [BIBCODE 1989BAAS...21R.714C ]
Ghedini, S. (1982). Software for Photometric Astronomy Willman-
      Bell, Richmond, VA, p. 46. [BIBCODE 1982spa..book.....G ]
Herczeg, T.J. (1980), in Close Binary Stars: Observations and
      Interpretation, ed. M.K. Plavec, D.M. Popper and R.K.
      Ulrich, (Dordrecht: Reidel), 89. [BIBCODE 1980IAUS...88...89H ]
Kwee, K. and van Woerden, H. (1956). B.A.N. 12, 327. [BIBCODE 1956BAN....12..327K ]


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