COMMISSION 27 OF THE I. A. U.
            INFORMATION BULLETIN ON VARIABLE STARS
                      NUMBER 849

  	                               Konkoly Observatory
        	                       Budapest
                	               1973 November 30

           CONCERNING VARIABLE STAR 3 OF M13


    In 1915 Shapley (1915, Mt.Wilson Contr.No.116) gave a list
of seven stars in the globular cluster M13 that he considered to
definitely vary in brightness. Subsequent investigations have
since shown five of these to indeed be variables, but the remaining 
two stars have not been studied in detail and the question
of the variability is still unanswered. In this note we report
the results of a study of one of the two stars, that denote  
Variable 3 of the cluster (Sawyer Hogg 1972, The Third Catalogue of
Variable Stars in Globular Clusters).
   For the realization of our investigation we had available 54
plates of the cluster taken in the years 1967 - 1969 with the 1.5m
reflector of the U.S. Naval Observatory. The brightness of Variable 3
was measured in relation to five nearby comparison stars using a
Becker type iris photometer. As a control, the non-variable star
Arp III-10 (Arp 1955, Astr.J. 60, 317) and the confirmed  variable No. 8,
which are in the same region, were also measured and reduced in the
same manner as for Variable 3. A quick look at the magnitudes derived
for Variable 3 showed that they were nearly all the same and hence
the variations, if any, are of very small amplitude. Calculation of
the standard deviation of the measures with respect to the mean gave
a value of +/-0.06 mag., equal to that found from the measures of the
non-variable control star. Furthermore, in both cases the histogram
of the distribution of the measures closely approximates the Gaussian
curve for the above sigma, indicating that the small differences in
the derived magnitudes can be entirely attributed to random measuring
errors. A histogram of the earlier measures of this star by Kollnig-
Schattschneider (1942, Astr.Nach. 273, 145) also gives a Gaussian 
distribution. In contrast, histograms of measures from the same plates
of known variable stars, both Variable 8 that we measured and the low
amplitude Variable 7 measured by Ibanez and Osborn (1973, IBVS No. 769)
show distinctly non-Gaussian shapes. We conclude that Variable 3 is
most likely not variable.

WAYNE OSBORN                            ORLANDO NARANJO and PARTICIA ROSENZWEIG 
Inst. Venezolano de Astronomia          Facultad  de Ciencias
Apartado 264                            Universidad de Los Andes
Merida, Venezuela                       Merida, Venezuela