COMMISSION 27 OF THE I. A. U.
        INFORMATION BULLETIN ON VARIABLE STARS
                    Number 1648

                                    Konkoly Observatory
                                    Budapest
                                    1979 July 27


      PHOTOELECTRIC PHOTOMERY OF 65 UMa (HR 4560)





   During a series of observations carried out in order to
check the constancy of some possible bright comparison stars in
selected areas, the brighter component of the visual
double star 65 UMa (HR 4560-4561) has been found variable. This
star was already pointed as probable variable in the Catalogue
of Bright Stars (Hoffleit, 1964) and included in the catalogue
of stars suspected in variability (Kukarkin et al., 1951) with
the number 101230.
   Observations of 65 UMa have been performed during two nights
of March (3/4 and 4/5) of the present year at an altitude of
2609 m in the Observatory of Sierra Nevada (Granada, Spain). The
observing equipment consisted of a 32 cm Cassegrain telescope,
a photoelectric photometer equipped with an unrefrigerated
EMI 6256 A photomultiplier and an analogical recorder. Only one
filter, close to the B of the Johnson's system was used.
   Magnitude differences in the sense star-comparison are
given in Figures 1 and 2 for both observing nights. The comparison
star was HR 4561 (6.81m; B9), the visual companion of HR 4560
(6.46m; A0) separated 63.2" and already checked for constancy by
Kurtz (1979). It has been also indicated that the system is a
spectroscopic binary (Becvar, 1964). Moreover, HR 4560 is a
triple star itself (A=7.2m, B=9.0m and C=8.3m) with separations
AB-C= 3.8" and A-B=0.3". Because of the small separation between A,
B and C, they were all measured as a whole and therefore it is not
possible for the moment to identify the real variable.
   The shape of the observed curves, seems to indicate that the
variation of light is due to an eclipsing binary within the above
mentioned multiple system of stars HR 4560. The depth of the

                      [FIGURE 1]
                      [FIGURE 2]

eclipses is of 0.09m in the filter used with a duration of
around four hours being of partial type. Two minima were 
observed corresponding to Julian Dates 2443936.48 and 2443937.35
approximately, therefore, a separation of 0.87d between minima
can be deduced.





                      A. GIMENEZ and J.A. QUESADA
                      Instituto de Astrofisica de
                      Andalucia
                      Apdo. 2144 - Granada
                      Spain


References:
Becvar, A.: Atlas Coeli II. Ceskoslovenke Akademie Ved. Praha 1964
Hoffleit, D.: Catalogue of Bright Stars. Yale University Observatory, 
       New Haven, Conn. 1964 [BIBCODE 1964cbs..book.....H ]
Kukarkin, B.V., Parenago, P.P., Efremov, Yu.I. and Kholopov, P.N.:
       Catalogue of Stars Suspected in Variability, Moscow, 1951
Kurtz, D.W.: Monthly Notices of the Royal Astronomical Society,
       186, 567, 1979 [BIBCODE 1979MNRAS.186..567K ]