COMMISSION 27 OF THE I. A. U.
       INFORMATION BULLETIN ON VARIABLE STARS
                    NUMBER 171


                                   Konkoly Observatory
                                   Budapest
                                   27 December 1966




             ON 12 RR LYRAE STARS IN M 3


      120 plates from the Moscow collection have been measured
and the magnitudes obtained for variables 21, 37, 40, 55, 64, 65, 81,
93, 94, 107, 108 and 119 [1] were combined with all observations
published up to the present [2 -13]. All magnitudes were reduced to
Kukarkin's system [14]. From season moments of maxima calculated 
by the modified method of superposition of the mean light curve
O - C diagrams were plotted (s. Figures. Open circles: denote 
uncertain values). On the basis of mean-weighted light curves also 
period-amplitude and period-asymmetry relations were deduced. Our
results differ slightly from those given in [13].


               DATA ON 12 RR LYRAE STARS IN M 3

          T0JDhel          P            Max       A
    21   2430000.415   0.5157336d      14.81m    1.46m   0.150    0.56m
    37          .241    .3266384       15.34     0.78     .390     .05
    40          .397    .5515416       15.01     1.31     .140     .48
    55          .032    .5298136       14.88     1.43     .125     .53
    64          .382    .6054590       15.32     0.94     .180     .30
    65          .332    .6683394       14.79     1.43     .140     .43
    81          .461    .5291108       14.86     1.44     .130     .55
    93          .420    .6023007       15.24     1.03     .150     .32
    94          .304    .5236936       14.90     1.43     .130     .51
   107          .039    .3090348       15.40     0.74     .400     .03
   108          .250    .5196047       14.94     1.36     .140     .53
   119          .192    .5177411       14.76     1.49     .170     .53


                      [FIGURE 1]
                      [FIGURE 2]

      Var 65 has an amplitude unusually large for RRb stars^*. On
P - A and P - xi diagrams it deviates from all the other stars. 
Generally our O - C diagrams (see figure) resemble those of  23. 
Nevertheless, the period-change could be expressed for none of the stars
by a parabolic law. It appears to have cyclical character. This can be
well seen for variables 37, 65, 93, 94, 107 and 119. The positive 
correlation [15] is likely to take place in this case.

References: 

    1. Sawyer, H., Publ. DDO II, 2, 1955. [BIBCODE 1955PDDO....2...33S ]
    2. Bailey, S., HA 78, 1913. [BIBCODE 1913AnHar..78....1B ]
    3. Baker R. and Baker, H., AJ 61, 283,  1956. [BIBCODE 1956AJ.....61..283B ]
    4. Belserene, E., AJ 57, 237, 1952. [BIBCODE 1952AJ.....57..237B ]
    5. Greenstein, J., AN 257, 301, 1935. [BIBCODE 1935AN....257..301G ]
    6. Hett, J., AJ 50, 15, 1942. [BIBCODE 1942AJ.....50...77H ]
    7. Larink, J., Berg. Abh. 2, 6, 1922. [BIBCODE 1922AAHam...2f...1L ]
    8. Muller, Th., Berl. Bab. Verof. 11, 1, 1933. [BIBCODE 1933QB4.B53b11h1... ]
    9. Roberts, M. and Sandage, A., AJ 60, 185, 1955. [BIBCODE 1955AJ.....60..185R ]
   10. Rybka, E., BAN 5, 257, 1930. [BIBCODE 1930BAN.....5..257R ]
   11. Schwarzschild, M., HC No. 437, 1940 [BIBCODE 1940HarCi.437....1S ]
   12. Slavenas, P., AN 240, 169, 1929. [BIBCODE 1930AN....240..169S ]
   13. Szeidl, B., Bud. Mitt. No. 58, 1965. [CoKon No. 58]
   14. Kukarkin, B. V. and Kukarkina, G. P., Per. Zv. 13, 239, 1961. [BIBCODE 1961PZ.....13..239K ]
   15. Balazs-Detre, J. and Detre, L., Bamb. Kl. Veroff. IV, 184, 1965. [BIBCODE 1965VeBam..27..184B ]



   Main Astronomical Observatory of the
   Ukrainian Academy of Sciences

                                                E. S. KHEYLO


  * The star belongs to the long period sequence. S.  [13] p. 72. Editor.