COMMISSION 27 OF THE I. A. U.
            INFORMATION BULLETIN ON VARIABLE STARS
                         Number 3333

                                           Konkoly Observatory
                                           Budapest
                                           31 May 1989

                                           HU ISSN 0374 - 0676


                  BV OBSERVATIONS OF IU AURIGAE


The light variability of IU Aur (HD 35 652) was observed photoelectrically by
Mayer (1965) who first found it to be an eclipsing binary. Since then, this
star has been observed photoelectrically by various authors (e,g. Eaton 1979,
Papousek and Vetesnik 1982, and Hui-song 1988), even though none of these
observations could cover the whole light curve satisfactorily. In these
previous observations some curiosity has been reported, such as temporal
changes of the light curve, changes in the maximum brightness and increasing
depth of the eclipse with time.

With the purpose to obtain a complete light curve, photoelectric observations
in BV were carried out with the 40-cm reflector at the Science Museum of


                              [FIGURE 1]

             Figure 1. Light curves of IU Aur (HD 35 652)


Kawasaki City during ten clear nights in 1987-88. The photoelectric photometer
was furnished with a Hamamatsu 1P21 photomultiplier tube. HD 35 619 was used
as the comparison star, which is the same one as used by the previous
photoelectric observers. In the present observations a total of 644
measurements were obtained in each colour.

During the present observations two primary minima could be covered as shown in
Table I, where the O-C values are calculated with Mayer's (1987) ephemeris:
J.D. 2438448.4068+1.811475d*E.

Table I. Times of observed minima

Hel.J.D.        Epoch        O-C
2447156.1688    4807       +0.0017d
2447167.0369    4813       +0.0009

Table II. Observed depths of both minima

Observer:         Mayer    Eaton   Papousek and     Hui-song   present
                 (1964)   (1979)   Vetesnik (1982)   (1988)    paper
Minimum
Primary B          0.48m    -      0.67m              0.74m   0.66m
Primary V          0.48   0.68m    0.63               0.73    0.64
Secondary B        0.37     -        -                0.58    0.52
Secondary V        0.37   0.54       -                0.58    0.54

Taking into account the above O-C values, the ephemeris has been revised as:

      Primary min.=Hel.J.D. 2438448.4068+1.8114754d*E

All the measurements in m_var-m_comp are plotted in Figure 1 and the depths
of both minima are listed in Table II. In Table II, the corresponding values
obtained from the previous light curves are also shown for comparison.

As is seen from Table II, the depths of minima in the present observations are
decreased as compared with Hui-song's observations. In order to confirm this
curious feature, further observations are highly desirable. The data of the
present observations given in m_var-m_comp (B,V) are available upon request.

I would like to express my thanks to Prof. M. Kitamura of National
Astronomical Observatory of Japan for his suggestion of the programme and kind
guidance.


SHIGEO OHMORI
Member of Japan Amateur Photoelectric Observers Association
(JAPOA)
Science Museum of Kawasaki City
Masugata 7-1-2, Tama-ku, Kawasaki City
Kanagawa-ken, 214 Japan

References:

Eaton, J.A. 1979, Inf. Bull. Var. Stars, No. 1614.
Hui-song, T. 1988, Chin. Astron. Astrophys., 12, 298. [BIBCODE 1988ChA&A..12..298L ]
Mayer, P. 1965, Publ. Astron. Soc. Pacific, 77, 436. [BIBCODE 1965PASP...77..436M ]
Mayer, P. 1987, Bull. Astron. Inst. Czechosl., 38, 58. [BIBCODE 1987BAICz..38...58M ]
Papousek, J., and Vetesnik, M. 1982, Scripta Fac. Sci, Nat. Univ. Brno, 12, 435. [BIBCODE 1982SFSPB..12..435P ]