COMMISSION 27 OF THE I. A. U.
         INFORMATION BULLETIN ON VARIABLE STARS
                     Number 1656

                                     Konkoly Observatory
                                     Budapest
                                     1979 August 4




  ON THE VARIABILITY OF THE RED GIANT v.Z. 238 = No. 138 IN M3


    This red giant (CI=1.53m) star was first investigated and
found to be variable by Russev (Russev, 1971) with a period of
82.53d and an amplitude of 0.24m relying on the measurements of
114 plates made at the Byurakan Observatory and Sternberg Institute 
in Moscow.
    A recent study of the plate material of the Konkoly Observatory 
showed that 73% of the measured magnitudes of this star
were within a range of +-0.06m around the mean and no light change
was suspected.
    Rediscussing this latter material the star has, indeed,
proved to be variable with a period of 53.28d which is approximately 
2/3 of the period found by Russev. The amplitude of the variable 
is about 0.15m, a slightly more than the observing errors.
The size of the dots in the Figure is proportional with the number 
of observations made in one night.

                          [FIGURE 1]

    Our new result does not change the conclusion of Olah's
paper. v.Z. 238 with its colour index (1.53) is the third reddest
giant star in the cluster, therefore indeed, from a given colour
index all red giants are variable in M3.
    We would like to emphasize that the investigations of the
variability of red giants in globular clusters are extraordinarily
interesting because of their evolutionary stage. Accurate 
photoelectric observations are especially needed.




	K. OLAH                   R.M. RUSSEV
	Konkoly Observatory       Department of Astronomy
	Budapest                  University of Sofia
	Hungary                   Bulgaria


References:
R.M. Russev, 1971, Per. Zvezdy 18, 171 [BIBCODE 1971PZ.....18..171R ]
K. Olah, 1979, Mitt. Sternw. Budapest, No. 73. [BIBCODE 1979CoKon..73....1O ]
						[CoKon No. 73]