COMMISSION 27 OF THE I. A. U.
          INFORMATION BULLETIN ON VARIABLE STARS
                       NUMBER 205

                                    Konkoly Observatory
                                    Budapest
                                    8 June 1967


       ON THE PERIOD OF THE BLAZHKO-EFFECT IN RZ LYRAE


The amplitude of the RRab variable RZ Lyrae changes periodically between 0.7
and 1.2 magnitudes in visual light. The following moments for the maxima and
minima of the amplitude have been compiled from all available data from 1909 to
1966. The majority of the moments were determined on the basis of the original
observations. Those taken from literature sources are asterisked.

Max J.D.   O-C   Min. J.D.   O-C      N   Observer
2418430    +3^d  2418486::    0^d   -108    A. Nijland
   8541     0       8600:     0     -107    "
   8658:   +2       8714:     0     -106    "
   8772    -2                       -105    "
2426150:  +11                       - 41    G. Lange
                 2426195::   -3     - 41    V. Tsessevich
   6246::  -9                       - 40    "
                    6552:    +6     - 38    "
   6600:   -3       6677+   +15     - 37    "
   6939:: -11       7005::   -4     - 34    "
                    8400::   -2     - 22    A. Saloviev
                 2430605+    -9     -  3    V. Tsessevich
2430911!   +6       0960!    -4        0    "
   1027:   +5                       +  1    "
                    1203!    +6     +  2    "
   1257!   +2       1320:    +6     +  3    "
                    2473+    -9     + 13    "
   3480:   +4       3524!    -6     + 22    A. Batyrev, L. Klepicova
   3835:   +7                       + 25    L. Klepicova,
                                            V. Tsessevich
                    3890!    +4     + 25    A. Batyrev, L. Klepicova
   4647:   -1                       + 32    L. Klepicova
                    6110::   -6     + 44    V. Tsessevich
                    7174!    -1     + 53    Yu. Migach, Yu. Romanov,
                                            V. Tsessevich
   7230:   -4                       + 54    Yu. Migach, Yu. Romanov
                    9306     +8     + 71    G. Lange
   9360!   +2       9404:   -12     + 72    "

The O-C's are residuals from the following elements fitting most exactly the
moments listed:

Max. J.D.= 2430904.3+116.654N+0.01034N^2

Min. J.D.= 2430963.6+116.654N+0.01034N^2

These elements indicate a lengthening of the secondary period of RZ Lyrae.


Yu. ROMANOV
Odessa Astronomical Observatory
March, 1967

References

1. A.A. Nijland, AN, 182, 1909 [BIBCODE 1909AN....182..311N ]
2. A.A. Nijland, Rech. Astron. Obs. Utrecht, VIII, 1923 [BIBCODE 1923RAOU....8....1N ]
3. A.A. Batyrev, P.Z., 1X, N1 (79), 1953
4. V.P. Tsessevich, B.A. Ustinov, Trudy GAICH, XXIII, 1953
5. L.A. Klepicova, P.Z., XII, N3 (99), 1959.