COMMISSION 27 OF THE I. A. U.
         INFORMATION BULLETIN ON VARIABLE STARS
                      NUMBER 633

                                      Konkoly Observatory
                                      Budapest 
                                      1972 February 25


               THE PERIOD OF EQ TAURI


From estimates of 392 exposures with the 25.4 cm reflector, the light elements

Min. = JD (Hel) 2436646.569+0^d.341351 E   (A)

have been determined. The 12 observed minima are listed in Table I, in which
the numbers of observations used to determine the values of O are listed
under n. For the three minima with n=24, 21 and 21, both descending and
ascending branches were completely covered.

The elements (A) give a much better light curve from the 44 visual observations
by Tsesevich than the ones he published. A normal minimum: 2430651.325, with
O-C=-0.096d for E=-17563, has been derived from his observations.

Magalashvili and Kumsishvili have attempted to fit two seasons of photoelectric
observations with a slight revision of the period, 0.41350d, of Tsesevich.
Their light curves show several discontinuities which do not appear in plots
using the period (A). Results from the reduction of their observations are
given in Table II, in which the subscripts I, B and V refer to observations
in integral, blue and visual light.

From the residuals in Table II alone, the elements

Min. = JD (Hel) 2440213.328+0.341346d E    (B)

have been derived. The mean O-C from the 21 times of minima, using
elements (B), is 0.0009, which is one-tenth of the mean from the 5 minima in
their Table 3. Primary minima in B and V have few observations.

Since the residuals, computed with elements (A), of the earliest and latest
observations are much too large for errors of observations, the period must be
considered to be variable.


BALFOUR S. WHITNEY
University of Oklahoma Observatory

References:

Tsesevich, V.P., Odessa Publication IV, Part III, 1954.
Magalashvili, N.L. and J.I.Kumsishvili, Abastumani Bull. 40, 2, 1971. [BIBCODE 1971AbaOB..40....3M ]


Table I.

Minima (Oklahoma)

       O       n    E         O-C

2436646.568    6     0      -0.001d
   6905.653    3   759      - .001
   6910.602   12   773.5    - .002
   6946.616   24   879      - .001
   7257.584    9  1790      - .003
   7267.658    3  1819.5    + .001
   7295.651   21  1901.5    + .003
   7355.554   29  2077      - .001
   7357.607   21  2083      + .004
   7367.676    6  2112.5    - .003
   7371.596    6  2124      - .003
   7706.633    6  3105.5    - .002

Table II.

Minima (Abastumani)

      C          E         O_I-C      O_B-C     O_V-C

2440212.492   -10446.5    -0.019d
    213.346    10449      - .019
    229.218    10495.5    - .016
    504.518    11302      - .024     -0.021d   -0.023d
    508.444    11313.5    - .023     - .021    - .023
    509.468    11316.5    - .022     - .022    - .022
    510.492    11319.5    - .023     - .020    - .022
    511.516    11322.5    - .020     - .021    - .022
    512.540    11325.5    - .023     - .023    - .022