COMMISSION 27 OF THE I.A.U.
              INFORMATION BULLETIN ON VARIABLE STARS
                           Number 1409

                                                     Konkoly Observatory
                                                     Budapest
                                                     1978 April 4


           PHOTOELECTRIC V LIGHT CURVE AND MINIMA OF RT And

We made 1032 photoelectric observations, in V light, of the eclipsing 
binary RT And (BD +52d3383 a) in 19 nights, between the end of 1972
and 1974.
   A photometer, equipped with an EMI 9502 photomultiplier and a
pair of Schott filters, GG14 + GG13 (2 mm), has been used, attached to the
40 cm looke refractor of the Teramo Observatory. From these data, eight times
of primary minimum and three of the secondary one have been calculated: to get
them we used the Kwee and van Woerden method (1956). Considering the times of
our primary minima, those reported by Williamon (1974) from J.D. 2439000 on,
and those given by Dean (1974), we obtained the linear ephemeris

  Hel. J.D.Min.I = 2441508.5550 + 0 62892990 E           (1)
                           +- 1         +- 4


   We did not consider the secondary minima in the above calculation,
because the relative measurements were not very reliable.
   The table below lists our times of minimum and the corresponding
(O-C)'s:


    J.D.        E          O-C       sigma

2441508.5563      0      +0.0013   +-0.0003
  41598.4911    143      -0.0009     0.0006
  41627.4228    189       0.0000     0.0001
  41886.5418    601      -0.0001     0.0001
* 42011.3852    799.5    +0.0007     0.0009
  42329.3092   1305      +0.0006     0.0003
  42330.5675   1307      +0.0011     0.0003
  42338.4240   1319.5    -0.0040     0.0004
  42339.3710   1321      -0.0004     0.0002
* 42367.3586   1365.5    -0.0002     0.0004
  42385.2832   1394      -0.0001     0.0002

* Not used in the calculation of equation (1)

                       [FIGURE 1]

   The observations have been reduced in phase by using (1) and the
resulting light curve (comp. star 1-var,) is shown in fig. 1.
   Stars BD +52d3377 and BD +52d3380 have been used as comparison
stars: the sequence of observations was

      Sky, comp. star 1, Var., comp. star 2, Var., .....

   With this procedure, we made a very careful analysis of the
possible variability of the main comparison star: within an accuracy of
0m.02 we can conclude that it is not so.
   Therefore the peculiarities of our light curve are to be attributed
to RT And itself: these peculiarities are mainly a great variability in the
levels of maxima and in the depths of the secondary minima, both from day to
day and from year to year.
   In a forthcoming paper, we will analyze the light curve of this
star using different methods of solution.


                                   S. MANCUSO  L. MILANO
                                   G. RUSSO    C. SOLLAZZO

                                   Capodimonte Astronomical Observatory
                                   Naples, Italy



References:

Dean, C.A.: 1974, Pub. Astron. Soc. Pac. 86, 912 [BIBCODE 1974PASP...86..912D ]
Kwee, K.K. and van Woerden, H.: 1956, Bull. Astron. Neth. 12, 327 [BIBCODE 1956BAN....12..327K ]
Williamon, R.M.: 1974, Pub. Astron. Soc. Pac. 86, 924 [BIBCODE 1974PASP...86..924W ]