COMMISSION 27 OF THE I. A. U.
        INFORMATION BULLETIN ON VARIABLE STARS
                     NUMBER 468


                                Konkoly Observatory
                                Budapest
                                1970 October 5


          A PERIOD CORRECTION FOR KP CYGNI

        The RR Lyrae-type star KP Cygni (20h02m14s,+40 58'2,
1900) was rediscovered this summer with the new Rodman blink
Comparator of the Maria Mitchell Observatory. The star was
subsequently examined under the direction of Dr. Dorrit
Hoffleit for a possible period correction; a period of
0d855933 had originally been found for the interval from
JD 2433617 to JD 2435299 (Whitney, Balfour S., Publ.Astr.
Soc. Pas. 68, 1956, p.269.) Observations were made from
approximately 950 plates taken with the 7.5" refractor of
the Maria Mitchell Observatory; the plates covered the
years 1926 to 1969 and ranged in Julian Days from 2424684.614
to 2440508.517. The brightness of the star varied between
magnitudes 12.5 and 14.05(pg).


                    [FIGURE 1]
     Fig. 1: Magnitude plotted against phase for the
published period of 0d855933. Dots are observations for the
     year 1939; crosses are observations for 1969.


        These more comprehensive observations suggest a
period correction as shown in Figures 1 and 2 for two
selected years, 1939 and 1969. The new elements thus determined 
are:
Max.- 2426178.579 + 0d855936 E.

Phases were computed using a reciprocal period of 1.168312.


                    [FIGURE 2]
 Fig. 2: Same as Figure 1 except for corrected period of
                 0d855936.


     I am deeply grateful to the National Science
Foundation for the grant that made this work possible.

                                           


Nantucket, Massachussetts
August 28, 1970

                           MARGARET VOGT