COMMISSION 27 OF THE I. A. U.
        INFORMATION BULLETIN ON VARIABLE STARS
                     NUMBER 319


                                    Konkoly Observatory
                                    Budapest
                                    1968 December 19



               NOTE ON GAMMA BOOTIS


      In "The General Catalogue of Variable Stars" Kukarkin
et al, (1) have classified Gamma Bootis as an unstudied
variable and stated that its brightness variations can from
time to time be represented with the period of 0.2903137d.

			[FIGURE 1]

	The V magnitudes of (a) Gamma Bootis,
     and (b) HR 5402 plotted against Julian Date


The star was observed by the present writer in the spring
of 1964 with a photoelectric photometer attached to Lowell
Observatory's 21-inch reflecting telescope. A 1P21 
refrigerated photomultiplier tube and standard BV filters
were used. The V magnitude and (B-V) colour index of the
comparison star, HR 5441, were determined on two nights
- they are equal to 6.390m +/- 0.005m and 0.523m +/- 0.003m,
respectively (mean errors estimated). The results of the
differential observations of Gamma Bootis, as well as of
the check star, HR 5402, reduced in the usual way, are shown
in Figs.1 and 2. Each point was derived from two comparisons

			[FIGURE 2]
	The B magnitudes of (a) Gamma Bootis,
	and (b) HR 5402 plotted against Julian Date.
	The arrows indicate phases 0 and 0.5,
        computed according to elements (I)			

"Gamma Boo - HR 5441" or "HR 5402 - HR 5441", in the case
of the check star. The observations suggest that brightness
of Gamma Bootis undergoes rapid fluctuations within about
0.01m.
      Our result differs greatly from that derived by
Magalashvili and Kumsishvili (2) from their photoelectric
observations, carried out in the years 1960, 1961 and 1962
at Abastumani Observatory. They found the star's brightness
to vary according to the elements

      Max. = J.D.2437020.440d + 0.2903137d E,         (I)

the amplitudes of the mean light-curves being equal to
0.05m and 0.11m in the yellow and blue light, respectively.
It is tempting to conclude that the large brightness 
variations present in 1960 to 1962 have virtually ceased in
1964. Such a conclusion may not be the correct one, however,
for Magalashvili's and Kumsishvili's result is open
to doubt; maxima of their mean light-curves were derived
from the 1960 observations alone while the minima - from
observations obtained in the years 1961 and 1962. It seems
therefore, that Magalashvili's and Kumsishvili's observations
indicate only that Gamma Bootis was by several
hundreds of a magnitude brighter in 1960 than in the
remaining two years, provided that Beta Bootis, the 
comparison star they used, was constant. Rapid fluctuations
of brightness of Gamma Bootis are also suggested by 
Magalashvili's and Kumsishvili's observations.
      According to our results the V magnitude of HR 5402
is equal to 6.285m (see Fig.1). It should be mentioned that
this value differs by 0.1m from the one quoted in the Yale
"Catalogue of Bright Stars" (3).


Wroclaw, Poland
December 3, 1968


                       MIKOLAJ JERZYKIEVICZ
                    Wroclaw University Observatory





References:

(1) Kukarkin, B. V., Parenago, P, P,, Efremov, Yu. I. and 
   Kholopov, P. N., "The General Catalogue of Variable Stars",
   second edition, Moscow 1968.

(2) Magalashvili, N. L., and Kumsishvili, J. J., Abastumani
   Astrophys. Obs. Bull. No. 32, p. 3, 1965.

(3) Hoffleit, Dorrit, "Catalogue of Bright Stars", Yale 
   University Observatory, New Haven, Connecticut, 1964. [BIBCODE 1964cbs..book.....H ]