COMMISSION 27 OF THE I. A. U.
        INFORMATION BULLETIN ON VARIABLE STARS
                    Number 2197

                                 Konkoly Observatory
                                 Budapest
                                 1982 September 9

                                 HU ISSN 0374-0676




             LIGHT ELEMENTS OF ST INDI



  The variability of ST Ind = CoD-48d13615 = S5110 was discovered
by Hoffmeister (1949) from photographic plates and visual estimates 
made in South Africa. He found for this system a W UMa-like
light variation with abnormal dispersion (Hoffmeister, 1955a).
Further, Hoffmeister (1955b) published the following linear light
elements: P = 0.401888d, T_0 = JD 2434274.407d; also he gave the
light curve and 24 times of minimum light. Seven of these minima
were determined photographically and the rest visually (Hoffmeister,
1956).
  In this note we present six times of minimum light determined
from 413 UBV observations made in August 1981 at CTIO*, in Chile,
with the 60 cm Lowell telescope.
  Individual minima are listed in Table I (the standard errors
are given in parenthesis). They were determined from the light
curve on each pass-band. The colour average of these minima are
listed in Table II (standard deviations in parenthesis) together
with the minima given by Hoffmeister.



    Table I. Individual times of minima of ST Indi.

                 JDHel 2444000+
      V              B                U
837.68610(13)  837.68667(07)    837.68566(14)
837.88998(37)  837.88917(33)    837.89031(41)
838.49086(12)  838.49074(14)    838.49054(24)
838.69297(29)  838.69267(18)    838.69272(19)
839.69607(32)  839.69588(14)    839.69631(15)
843.51579(43)  843.51519(25)    843.51471(42)


* Cerro Tololo Interamerican Observatory is operated by AURA,
 Inc., under contract with the NSF (USA).



                Table II. Minima of ST Indi

Meth.  JDHel.          w          E     (o-c )   (o-c)'   (O-c )"
     2400000+
Pg   34274.417        0.1   -26289.5   0.0057             0.0070
Pg   34302.319        0.1   -26220     -.0231             -.0220
Pg   34478.574        0.1   -25781.5    .0065              .0068
Pg   34488.628        0.1   -25756.5    .0134              .0137
Pg   34490.634        0.1   -25751.5    .0100              .0103
Vis  34505.505        0.1   -25714.5    .0114              .0115
Vis  34507.494        0.1   -25709.5   -.0090             -.0089
Pg   34542.467        0.1   -25622.5    .0002              .0002
Vis  34547.471        0.1   -25610     -.0193             -.0194
Pg   34550.567        0.1   -25602.5    .0626              .0625
Vis  34561.350        0.1   -25575.5   -.0053             -.0054
Vis  34562.363        0.1   -25573      .0030              .0029
Vis  34563.390        0.1   -25570.5    .0253              .0252
Vis  34567.373        0.2   -25560.5   -.0105             -.0106
Vis  34568.392        0.2   -25558      .0038              .0037
Vis  34568.598        0.2   -25557.5    .0089              .0087
Vis  34569.390        0.2   -25555.5   -.0029             -.0030
Vis  34569.594        0.2   -25555      .0002              .0000
Vis  34570.387        0.2   -25553     -.0106             -.0108
Vis  34570.602        0.2   -25552.5    .0034              .0033
Vis  34571.393        0.2   -25550.5   -.0093             -.0095
Vis  34571.598        0.2   -25550     -.0053             -.0054
Vis  34573.400        0.2   -25545.5   -.0117             -.0119
Vis  34573.606        0.2   -25545     -.0067             -.0068
UBV  44837.68622(50)  1.2       -5     -.0011   -.0009
UBV  44837.88982(59)  0.4       -4.5    .0016    .0018
UBV  44838.49075(16)  0.8       -3     -.0003   -.0002
UBV  44838.69279(16)  2.0       -2.5    .0008    .0009
UBV  44839.69607(22)  2.0        0     -.0006   -.0007
UBV  44843.51530(54)  0.8       9.5     .0007    .0002

  A least squares linear solution for the 24 photographic and
visual minima gives the following light elements:

    Min I = HJD 2434424.1119d + 0.401884d E

                     +-.0050   +- 000015 m.e.       (1)

while for the present six photoelectric minima a least squares
solution gives the following linear light elements:

    Min I = HJD 2444839.69675d + 0.401930d E

                     +-.00021   +-.000049 m.e.      (2)


  These results show the period to be constant within the
errors, Finally a least squares linear fit was performed with
all the minima giving the following light elements (cycles were
calculated with the period given in ( 1 ) ) :

      Min I = HJD 2444839.6967d + 0.40188233d E

                       +-.0010   +-.00000010 m.e.


  The cycles E and the residuals (O-C) from the latter ephemeris
are listed in Table II while the columns labeled (O-C)' and
(O-C)" refer to the residuals from (1) and (2), respectively.
  Differential V and colour curves are displayed in Figure 1.

                      [FIGURE 1]

ST Ind is a typical W UMa star as previously classified, eclipses
are partial and of equal depths (0.49 mag), thus letting as
arbitrary the distinction between primary and secondary minima.
Maxima are highly curved and the light at phase 0.25 exceeds in
0.02 mag the light at phase 0.75. Colours are almost constant
throughout the period.





       VICENTE J. MUGHERLI AND MIGUEL A. CERRUTI
       Instituto de Astronomia y Fisica del Espacio
       CC 67 Suc. 28 1428 Buenos Aires
       Argentina





References:

Hoffmeister, C. 1949, Astron. Abh., Erg. zu den Astron. Nach.,
   12, No. 1
Hoffmeister, C. 1955a, Astron. Nach., 282, 260 [BIBCODE 1955AN....282..257H ]
Hoffmeister, C. 1955b, Mitt. uber Verand. Sterne, No. 186
Hoffmeister, C. 1956, Veroff. der Sternw. Sonneberg, 3, No. 1 [BIBCODE 1956VeSon...3....1H ]