COMMISSION 27 OF THE I.A.U.
              INFORMATION BULLETIN ON VARIABLE STARS
                           Number 1245

                                                  Konkoly Observatory
                                                  Budapest
                                                  1977 February 28


                ON THE BLAZHKO EFFECT IN AR Ser

As has already been reported (V.P. Tsessevich, AC, No. 885,
1975) AR Ser shows anomalous Blazhko effect. The height of 
maximum light of this star as well as its time shift (O-C) 
relative to linear elements vary periodically.
   I made observations of this star in the interval JD 2442126-
JD 2442994.
   For the Blazhko effect the following formula has been 
obtained by us:

   1) T_max = 2442195.5+ 108.4 x n

   The shift of the moments of maximum light (O-C) has been 
determined from the elements:

   2) Max.hel. JD = 2442126.441+ 0.575092 E.

   On the basis of our observations we may conclude that the
amplitude of Blazhko effect in AR Ser changes, possibly in 
cyclic way (see Figures 1, 2, 3).
   The moments of maximum light, the heights of maximum light,
E_2, (O-C)_2 and phases of Blazhko effect, derived from formula (1)
are given in Table below:


                       Table

  Max.hel.JD     m_v     E_2   (O-C)_2    Psi1

2442126.441     12.09      0    0.000    0.363
    134.504     11.99     14     .012     .437
    137.383     11.96     19     .015     .464
    187.406     11.63    106     .005     .925
    198.338     11.55    125     .010     .026
    199.489     11.63    127     .011     .037
    206.390     11.68    139     .011     .100
    214.432     11.78    153     .002     .175
    218.464     11.85    160     .008     .212
    221.333     11.89    165     .002     .238
    225.380     11.91    172     .023     .276
    244.342     12.22    205     .007     .451
    486.497     12.07    626     .048     .684
    490.492     12.02    633     .018     .721
    512.390     11.84    671     .062     .923
    542.426     12.09    723     .194     .200
    546.934:    12.13:   730     .144     .237
    576.331     12.16    782     .168     .512
    580.360     12.14    789     .172     .550
    868.463     12.16   1290     .153     .208
    872.474     12.18   1297     .139     .245
    918.394     12.18   1377     .051     .669
    922.373     12.12   1384     .005     .705
    926.401     12.14   1391     .007     .743
    934.448     12.05   1405     .003     .817
    937.340     12.04   1410     .019     .844
    945.372     12.02   1424     .000     .918
    949.420     11.87   1431     .022     .955
    953.454     12.04   1438     .031     .992
    960.355     11.97   1450     .031     .056
    979.340     12.15   1483     .038     .231
    990.324     12.18   1502     .095     .332
    994.349:    12.25:  1509     .094     .369


                      B.N. FIRMANYUK

               Odessa Astronomical Observatory



                     [FIGURE 1]
                     [FIGURE 2]
                     [FIGURE 3]