COMMISSION 27 OF THE I. A. U.
          INFORMATION BULLETIN ON VARIABLE STARS
                     Number 2869

                                        Konkoly Observatory
                                        Budapest
                                        25 February 1986

                                        HU ISSN 0374 - 0676


               ON THE LIGHT CURVE OF AI Scl *

  The possible delta Scuti star AI Scl (HR359,HD7312) is only little
investigated. In the 'Third Supplement to the Third Edition of the
General Catalog of Variable Stars' AI Scl is listed as a possible
delta Scuti star with a period of approximately 70min. This is based on
Eggen's (1973) observations who called the star an ultrashort-
period Cepheid arid presented two short parts of the light curve.
In 1976 Eggen mentioned that spectrograms suggest the existence of
a binary. Radial velocities are given in Buscombe and Morris
(1958) and Buscombe (1963). Morris and DuPuy (1980) investigated
AI Scl photometrically in the UBV system. They found two periods
of 64min and 134min, respectively.
   The observations were carried out on 23./24.11.1984 with the
Danish 50cm telescope at La Silla/Chile equipped with the 4-channel 
Stomgren photometer. The integration time was 30sec per channel. 
Although no comparison star was used the quality of the measurements 
are quite good.
  After the transformation into the standard system the averages
were calculated and subtracted from the data. Then the remaining
residuals were fitted simultaneously with two periods. The
function fit was :

     M(t) = ZP* SUM  (ampl(i)*sin(2*f(i)t + 2(pi)*(phi(i))), i=1,2

   Afterwards the estimated frequencies were weighted and the
means yielded two periods of :

     P = 116.4 +- 3.5min        and      P = 60.0 +- .1min

--------------

   * Based on observations collected at the European Southern
Observatory (ESO), La Silla/Chile.



                            [FIGURE 1]

 Fig.1 shows the residuals from the b-channel. The solid line presents
the fit, while the triangles are drawn in order to make time
gaps in the observations visible.
  There exists some indications for a third period, but the time
base is too short to confirm this.



                         HARTMUT SCHNEIDER
                             and

                         WOLFRAM KOLLATSCHNY

                         Universitats-Sternwarte
                         Geismarlandstr. 11
                         D-3400 Gottingen
                         F.R.G.



References :

Buscombe, W. Mon.Not.R.Astron.Soc. 126, 29 (1963) [BIBCODE 1963MNRAS.126...29B ]
Buscombe, W., Morris, P.M. Mon.Not.R.Astron.Soc. 118, 609 (1958) [BIBCODE 1958MNRAS.118..609B ]
Eggen, O.J. Astrophys.J 180, 857 (1973) [BIBCODE 1973ApJ...180..857E ]
Eggen, O.J. Publ.Astron.Soc.Pac. 88, 402 (1976) [BIBCODE 1976PASP...88..402E ]
Morris, S., DuPuy, D. Publ.Astron.Soc.Pac. 92, 303 (1980) [BIBCODE 1980PASP...92..303M ]