COMMISSION 27 OF THE I. A. U
        INFORMATION BULLETIN ON VARIABLE STARS
                     NUMBER 220

                                    Konkoly Observatory
                                    Budapest
                                    16 August 1967


   SECONDARY PERIOD OF THE RRab STAR AR SERPENTIS


This variable star of RR Lyrae type discovered by C. Hoffmeister was
investigated by Tsessevitch, who gave the new elements (Astr. Circ. 353. 3):


                         [FIGURE 1]

Max. hel.=2430472.469+0.^d57514215*E

and found strong fluctuations in the period suggesting the presence of
Blashko-effect.

This year 960 photoelectric observations have been obtained in blue and yellow
with the 24" telescope of the Konkoly Observatory. 11 light maxima were
observed, which showed large variations in height and phase.

In the upper part of the Figure the variations in the brightness of the light
maxima and light minima are plotted against Julian date. The extreme values of
the amplitude are 1.32 and 0.49 mag. in blue, 1.09 and 0.41 mag. in yellow,
respectively.

In the lower part of the Figure the phase oscillation of the light maxima (in
blue) is shown. Both the amplitude and phase oscillations suggest a secondary
period of about 105 days, with the same phase-relation as in the RRab star RV
UMa (P_o=0.^d468, P_b=90.^m8; Budapest Mitt. 34, 1957).

Next year the observations will be continued in order to determine a more exact
value for the secondary period.


Konkoly Observatory, Budapest
                                             B. SZEIDL