COMMISSION 27 OF THE I.A.U.
                 INFORMATION BULLETIN ON VARIABLE STARS
                              Number 2982

                                                         Konkoly Observatory
                                                         Budapest
                                                         5 February 1987

                                                         HU ISSN 0374 - 0676


                  NEW B,V LIGHT CURVES OF LS DELPHINI

LS Del (BD+19d4574, HD199497) was discovered as a W UMa type eclipsing
variable by Bond (1976) from photometric and spectroscopic observations. Bond
gave a light curve, based on only 24 points, in the uvby photometric system
and derived a period of 0.3638 days. According to the list published in the 4th
edition of GCVS, the visual magnitude of the system varies from 8.61 to 8.76.
The variable received its current name in 1981 (Kholopov et al., 1981).
   New photoelectric observations of LS Del in B, V colors were made by us,
with the 60-cm Cassegrain telescope at the Xinglong station of the Beijing
Astronomical Observatory, on 4 nights of August 1986. In the observations,
BD+19d4576 and +19d4590 were used as comparison and check stars, respectively.
Data concerning them are summarized in Table I. One primary and two secondary
minima were obtained. Those minima are listed in Table II, together with the
time of minimum of LS Del obtained by Bond. The new light elements obtained
as follows:

        Hel MinI=2,446,670.1658 + 0d.3639207 E
                           +-22          +-3


                   Table I
Data for variable, comparison and check stars

   BD         Name          Sp.      V       B-V

+19 4574   LS Del  MinI     G5IV    8.89     0.89
                   MinII            8.87     0.90
                   Max              8.73     0.89

+19 4576  Comparison        K0      8.50     1.00

+19 4590   Check            F5V     7.90     0.50


           Table II
  Times of minima of LS Del

 JD hel        E      O-C

2440000.+
2687.418 *  -10944  +0.0003
6668.1609   -5.5    -0.0033
6670.1686    0      +0.0028
6671.0744   +2.5    -0.0012

* Bond (1976).


   The period found by us is slightly longer than the old one. The light
curves are shown in Figure 1 where the differential magnitudes deltaB, deltaV
for the system relative to the comparison star have been plotted against the
phases which were calculated with the elements given in this article.

                          [FIGURE 1]

   From the new observations, the depth of primary minimum is 0.16 mag. in
V band, a little deeper than 0.15 mag. given by Bond. The difference between
the depth of the primary and secondary minima is of 0.02 mag. The detailed
discussion will be given elsewhere.


                           WANG RUYOU
                           LU WENXIAN
                           FAN QINGYUAN

                        Shanghai Observatory
                          Academia Sinica
                          Shanghai, China


References:

Bond, H.E. 1976 I.B.V.S., No. 1214
Kholopov, P.N., Samus, N.N., Kukarkina, N.P., Medvedeva, G.I., Perova, N.B.,
   1981, I.B.V.S., No. 1921