COMMISSION 27 OF THE I. A. U.
          INFORMATION BULLETIN ON VARIABLE STARS
                        Number 936

                                    Konkoly Observatory
                                    Budapest
                                    1974 October 22


          MAXIMA OF THE RR_S-VARIABLES CY Aqr
                  DY Her AND DY Peg

During test runs of the newly designed photoelectric double beam
photometer for the 106cm Cassegrain reflector of the Hoher List
Observatory these RR_S-Lyrae stars have been observed in B and V.
The photometer allows the simultaneous photometric monitoring of
the variable and a comparison star within the field of the telescope 
with fairly high time resolution.
The maxima times of the individual B-light curve cycles given in
the table were derived by using Pogson's method. The epochs and
(O-C)'s are based on the light elements given by Kukarkin et al.
(Gen.Cat.Var.Stars 1, 19, 1969) for CY Aqr, Hardie and Lott 
(Astrophys. Journal 133, 71, 1961) for DY Her and Grigorevsky and
Mandell (Perem. Zvezdy 13, 190, 1960) for DY Peg. On the average
the deviations from these elements amount 9.4 per cent of the
period for CY Aqr, 1 per cent for DY Her, and 7.6 per cent for
DY Peg as can be seen from the last column of the table. The
"noise" of the period length of the individual cycles amounts to
+-0.65% for CY Aqr resp. +-1.56% for DY Peg, which is slightly 
above the present time resolution of our equipment for such short
periods.
                          Table

Star     Maxima J.D. hel       E             O-C     (O-C)/P
           244 0000 +
                d                            d         %
CY Aqr  1958.3639+-0.0003    47589         -0.0059    - 9.7
        1959.2799+-0.0010    47604         -0.0055    - 9.0
        1959.3405+-0.0003    47605         -0.0059    - 9.7
        1959.4018+-0.0003    47606         -0.0057    - 9.3
        1959.4634+-0.0003    47607         -0.0051    - 8.4
        1959.5234+-0.0003    47608         -0.0062    -10.2

DY Her  1840.4222+-0.001     56522         -0.0015    - 1.0

DY Peg  1937.4701+-0.001     80438         -0.0062    - 8.5
        1937.5444+-0.001     80439         -0.0048    - 6.5
        1957.3785+-0.001     80711         -0.0066    - 9.1
        1957.4535+-0.001     80712         -0.0046    - 6.3
        1957.5243+-0.001     80713         -0.0067    - 9.2
        1957.5998+-0.001     80714         -0.0042    - 5.7


                             E.H. GEYER           M. HOFFMANN
                             Astron. Institute der Universitat
                             Bonn, Observatorium Hoher List