COMMISSION 27 OF THE I. A. U.
         INFORMATION BULLETIN ON VARIABLE STARS
                      NUMBER 668

                                       Konkoly Observatory
                                       Budapest
                                       1972 April 29


            TIMES OF MINIMA OF ECLIPSING BINARIES


During the summer and fall of 1971, the writer observed several eclipsing
binaries photoelectrically with the 12-inch Clark refractor at Mt. Hamilton.
A 1P21 photomultiplier, refrigerated with dry ice, and a yellow filter
(Corning No. 3385) were used in the photometer. Using magnitude differences
with respect to nearby comparison stars, times of eclipse minimum were
obtained for eight binaries. The individual times of minimum are listed in
the following table. These are primary eclipse minima, unless noted
otherwise. The O-C values were computed using the elements listed in the
1969 General Catalogue of Variable Stars, except for MR Cyg (see remarks).

star     J.D. Min. hel.   estim.         O-C
         2441000+         error
BX And   210.805        +-0.001 day    +0.003 day
         213.858          0.001        +0.004
         276.697          0.001        +0.002
XX Cep   214.61           0.01         -0.01
CQ Cep   193.861^x        0.002        +0.009
         207.820          0.002        +0.018
         216.854^x        0.002        +0.025
         222.598          0.005        +0.024
TV Cet   275.962          0.001        +0.042
MR Cyg   172.810          0.005        -0.003
         209.707          0.002        -0.001
         214.735          0.005        -0.004
S Equ    218.866          0.005        +0.004
SW Lac   192.7654^x       0.0002       -0.0254
         192.9264         0.0005       -0.0248
U Sge    203.802          0.001        +0.007

^x secondary eclipse

XX Cephei: An O-C curve has been published by J.M. Kreiner (1971), based
on different elements. The observed minimum; with an O-C of -0.05 day from
those elements, seems to be consistent with an interpretation in terms of a
cyclic period variation.

TV Ceti: The present observations indicate primary eclipse is partial, with
a depth of 0.72m, and a duration of 7.4 hours. The large O-C indicates that
revision of the elements is desirable. Using the epoch of the G.C.V.S.
elements, and the observed minimum, the elements derived are:

Hel. J.D. Min.=2441275.962+9.1032884 E.

MR Cygni: The elements used to compute the O-C values are those given by J.C.
and R.H. Koch (1962):

Hel. J.D. Min.=2427013.6177+1.6770337 E

SW Lacertae: A light curve was assembled from the observations, which
included photometry from five nights. This indicated that the visual
magnitude difference between primary minimum (phase 0.0) and phase 0.25 was
0.81m.


April 10, 1972

                              ALLAN MEYER
                              Board of Studies in
                              Astronomy and Astrophysics
                              University of California,
                              Santa Cruz

References:

J.M. Kreiner, Acta Astronomica 21, no. 3, p. 365 (1971) [BIBCODE 1971AcA....21..365K ]
J.C. Koch, R.H. Koch, Astronomical Journal 67, 462 (1962) [BIBCODE 1962AJ.....67..462K ]