COMMISSION 27 OF THE I. A. U.
         INFORMATION BULLETIN ON VARIABLE STARS
                     NUMBER 592

                                Konkoly Observatory
                                Budapest
                                1971 November 12



         ONE NEW AND FOUR UP-DATED VARIABLE STARS


     Among the results obtained by the, summer students
at the Maria Mitchell Observatory are the up-dating of 
observations of three long period variables and one RR Lyrae
type.
     V734 Cygni was estimated by Miss Karen Kwitter on
over 1280 Nantucket plates taken between 1916 and 1971. The
best constant period she was able to obtained 310 days,
showed pronounced systematic deviations of observed from
computed times of maximum. By fitting a cosine term to the
deviations, I find the following relation to hold over the
68 cycles represented:

       Max = JD 26590 + 310E - 5.5 cos 6.8deg (E-16).

      MM Sgr was rediscovered by Miss Kwitter with the
Rodman Blink Microscope. On the basis of 640 observations
on Harvard and Nantucket plates dating back to 1928, she
was able to improve the period given in the General Catalogue
of Variable Stars (1970 ed) from 203 to 202.3 days.
      NW Sgr was similarly rediscovered by Miss Esther Hu,
who made estimates of its brightness on 440 plates 1957-71,
but did not attempt to verify the period. I find that her
observations, embracing 32 cycles, satisfy both the 1948
zero point (J.D.32710) and period of 161.5 days given in
the General Catalogue so precisely that it almost seems
wrong to classify the star as semi-regular!
       S Comae is an RRab type star that has been suspected 
of having a changing period. Miss Pamela Bonnell redetermined 
the period from 100 Nantucket plates taken 1964-71
and one earlier plate taken in December 1934. She obtains,

       Max = JD 40654.641 + 0.5865907d E

       This differs by only 6.10^-7 d from the period given
in the General Catalogue; however, the new and the 
previously published epochs of maximum are more consistent
with the new period. The new observations give no indication 
that the period is changing.

A New Variable  at 18h38m24s, -20d22.2' 1900, mag. 14.2-15.5 pg,
                    which I had discovered on Harvard plates, is
                    type RRab. In 1970 Miss Linda Lucignani
   [FIGURE 1]  
                    examined it on 114 Harvard and 355 Nantucket
                    plates for 1924-70. From her magnitude estimates 
                    I deduce,

Max = JD 33858.392 + 0.5633812d E.

The chart is approximately 10' x 10'.




October 1971               DORRIT HOFFLEIT
                       Maria Mitchell Observatory
                         Nantucket, Mass. U.S.A.