COMMISSION 27 OF THE I.A.U.
              INFORMATION BULLETIN ON VARIABLE STARS
                           Number 1283

                                                    Konkoly Observatory
                                                    Budapest
                                                    1977 May 25


        WANTED: PHOTOELECTRIC AND SPECTROSCOPIC
      OBSERVATIONS OF THE UNUSUAL SYSTEM, V389 CYGNI

Between 1936 and 1992 Paul Guthnick published a series of
papers on V389 Cygni, assumed to be the 3d.3 spectroscopic binary
component A of ADS 14682. His conclusions are briefly summarized
in the Remarks in the GCVS.
   Guthnick found two Cepheid-like periods, apparently unrelated 
to the SB period, of 1.12912d and 1.19328d. These two periods
alternated with one another at intervals of one to three weeks,
being separated by intervals or random or non-variability. As
each period recurred it did so at precisely the phase it would
have had if there had been no interruptions. Guthnick interpreted 
the system as consisting of two Cepheids whose pulsations account 
for the deviations of the observed radial velocities from
their mean curve.
   These remarkable conclusions have never been verified. The
spectroscopic binary orbit has been questioned by Luyten and by
Batten. Testing the published radial velocities for spurious
periods, I find that they can be almost as well represented by
a period of 0.7665126d as by Guthnick's 3.31322d. The two light
periods are related by 1/P1 - 1/P2 = 1/21.0000. A beat period of
21 days is not obvious from the plot of the photoelectric 
observations. An examination of these data reveals no better 
period than those published.
   After a lapse of more than 35 years, extensive photoelectric
and spectroscopic observations are warranted to verify and 
update Guthnick's conclusions, or to arrive at an alternative 
plausible interpretation.


                                 DORRIT HOFFLEIT

                                 Maria Mitchell Observatory
                                 Nantucket, Mass. 02554, U.S.A.



References:

Batten, A.H. 1967, Pub. Dominion Astrophysical Obs., 13, 251 [BIBCODE 1967PDAO...13..119B ]
Guthnick, Paul 1936, Ast. Nachrichten, 261, 217 [BIBCODE 1936AN....261..217G ]
               1937, Abh. d. Preus. Ak. d. Wissen., Nr. 3
               1939, ibid., Nr. 6
               1942, kbkd., Nr. 7
               1942, Die Sterne, 22, 129
Luyten, W. 1936, Ap. J., 84, 85 [BIBCODE 1936ApJ....84...85L ]