COMMISSION 27 OF THE I. A. U.
          INFORMATION BULLETIN ON VARIABLE STARS
                       Number 2716


                                       Konkoly Observatory
                                       Budapest
                                       2 May 1985

                                       HU ISSN 0374 - 0676

                           FS Lup

                VARIABLE STAR TYPE EA OR EB?*

   The star FS Lup was detected by Hoffmeister (1963) and first listed 
under number S7620. It has been referred to as a variable of type EA, its
brightness ranging between 11.5 - 12.5 (photographic).
   The equatorial and galactic coordinates of this star are:
   alpha = 14h 48m 45s       l = 321.36deg
                     (1950.0)
   delta = -51deg 13.3'      b = + 7.07deg

Figure 1 reproduces the identification chart.
   Until now FS Lup has not been put under systematic observation so as
to confirm or refute its type of variability or determine the graph of
its light curve so that the period of variation of its brightness could
be defined (Kholopov, 1985).

                            [FIGURE 1]

 Figure 1. Finding chart (in B) for the variable star FS Lup


* based on observations collected at ESO/LA SILLA, CHILE.




  In Table I we mention the periods of observation and the means of
investigation.

                          Table I



Period          Telescope      No of nights    Photometry    Observer
May 1982     T61cm, Bochum/ESO        5           U.B.V.     TERZAN, A.
May 1983     T61cm, Bochum/ESO,       3           U.B.V.     TERZAN, A.
June 1984    T1m / ESO                4           U.B.V.     DIDELON, P.

  The light curve in V (Figure 2) resulting from the collection of all
the observational data in one single phase seems to point out that star
FS Lup is more likely to be an eclipsing variable star of type EB,
not EA.

                         [FIGURE 2]

 Figure 2. Light curves V, B - V, U - B for the variable star FS Lup




  The ephemeris of the variation of its brightness is:
  PJJHel = 2 445 108.56035d + 0.3813973d.E.
                                   +\-5

with amplitude about 1 magV and depth of the secondary minimum in the
order of 0.5 magV.
         





    Besides, we note that the period PJJHel, graphed between two principal
maxima varies very little (+\- 0.0000005d.P.). It is relatively short
(0.3813973d) for a star type EB.

    In fact, the histogram graphed by Petit (1982) after the data collected 
from the "General Catalogue of Variable Stars" (Kukarkin et al., 1969)
on the eclipsing variable stars type EA and EB points out that the number
of EA or EB with a period inferior to 0.4d does not exceed 5.

    The determination of other different parameters as well as the 
discussion on the variability of the period of this star will be the aim of
our further research.





            A. TERZAN                             P. DIDELON
       Observatoire de Lyon                Observatoire de Strasbourg
       69230, St Genis Laval               67000, Strasbourg
           France                               France





References:

Hoffmeister, C., 1963, A.N. 287, p. 59. [BIBCODE 1963AN....287...59H ]
Kholopov, P.N., 1985, private communication
Kukarkin, B.V., Kholopov, P.N., Efremov, N., Kukarkina, N.P., Kurochkin,
      N.E., Medvedeva, G.I., Perova, N.B., Fedorovich, V., Frolov, M.S.
      1969, General Catalogue of Variable Stars, 3th edition.
      Moscow.
Petit, M. 1982, Les Etoiles variables, Masson, Paris, p. 191. [BIBCODE 1982lev..book.....P ]