COMMISSION 27 OF THE I. A. U.
        INFORMATION BULLETIN ON VARIABLE STARS
                    Number 2098

                                Konkoly Observatory
                                Budapest
                                1982 March 4

                                HU ISSN 0374-0676





 PHOTOELECTRIC OBSERVATIONS OF THE ECLIPSING BINARY IM AURIGAE



  The variability of IM Aurigae (BD + 46d985 = HD 33853)
was discovered by Strohmeier (1959). The variable star, designated 
BV 267, was recognized photographically as an eclipsing binary
with a period of 0.684315d and Beta Lyrae type light curve
(Strohmeier et al. 1963). Spectroscopic and photoelectric 
observations led to a period of 1.24730d while the light curve 
appeared to be of Algol type (Margoni et al. 1966). Kondo (1966)
confirmed these results independently with his photoelectric
observations, and solved the orbital parameters using the method
of Russell-Merrill. Mammano et al. (1966) investigated this
single line eclipsing binary spectroscopically and calculated
the orbital elements. They also deduced the absolute properties
of the system by combining their spectroscopic elements with
the photometric ones given by Kondo (1966). Dworak (1974) obtained
one photoelectric minimum and calculated the light elements as,


    Min I JD Hel = 24 40 515.5465 + 1.247296d.E


collecting the times of minima obtained photoelectrically by
Kondo (1966) and Margoni et al. (1966).
  The system was observed photoelectrically at the Ege University 
Observatory on 11 nights from October 1980 to November
1981. The observations were made in yellow and blue colours with
the 48 cm Cassegrain telescope equipped with an unrefrigerated
EMI 9781 A photomultiplier tube and Johnson's standard B,V
filters. A total of 354 and 343 individual points were obtained
in B and V colours, respectively. BD + 47d1126 was used as
comparison and BD +46d0979 as check star. All the differential
observations (comparison minus variable) were corrected for the
differential extinction. During the observations two primary
and three secondary minima were obtained. These are given in
Table I.
               Table   I
       Times of Minima of IM Aur
-----------------------------------------
Hel Min JD        Min     Filter   O-C
-----------------------------------------
24  44 517.4706   II      B,V    -0.0009
       567.3674   II       "     +0.0043
       569.236    I        "     +0.002
       893.5270   I        "     -0.0027
       931.5674   II       "     -0.0046
-----------------------------------------


The new light elements are recalculated collecting all the
photoelectric minima published up to date. These elements are
as follows:


     Hel Min JD = 24 38 327.7922 + 1.2472906d.E.
                            +-11         +-3


                        [FIGURE 1]

The light and colour curves are presented in Figure 1 where
the magnitude differences have been plotted against the phases.
The phases in Figure 1 and O-C values in Table I were calculated
with the above new light elements. From Figure 1 it can be seen
that the system is reddening at the primary Minimum and the
depth of secondary minimum is changing.
  This project is partly supported by the Turkish Scientific
and Technical Research Council.





         N. GUDUR, O. GULMEN and C. SEZER
         Ege University Observatory
         Bornova-Izmir-Turkey





References:

Dworak, T.Z.: 1974, IBVS No. 916.
Kondo, Y.: 1966, Astron.J. 71, 46. [BIBCODE 1966AJ.....71...46K ]
Mammano, A., Margoni, R., Perinotto, M.: 1966, Contr.
  Dell'Osservatorio Astrofisico Dell'Universita Di Padova in
  Asiago, No. 192.
Margoni, R., Mammano, A., Biolchini, R. and Bartolini, C.:
  1966, IBVS No. 131.
Strohmeier, W.: 1959, Verof.Remeis-Sternwarte Bamberg, Band V,
  No. 3.
Strohmeier, W., Knigge, R. and Ott, H.: 1963, Verof.Remeis-
  Sternwarte Bamberg, Band V, No. 17.