COMMISSION 27 OF THE I. A. U.
         INFORMATION BULLETIN ON VARIABLE STARS
                     Number 1882

                                   Konkoly Observatory
                                   Budapest
                                   1980 December 10

                                   HU ISSN 0374-0676



          FURTHER ON THE PERIOD OF NY CEPHEI



  NY Cephei (HD 217312) was found by Heard and Fernie (1968)
to be a double-lined spectroscopic binary with a period of
15.2767d+-0.0010d. Rao (1972) and Madore and Percy (1973)
independently observed light variations which strongly suggested
that this system was also an eclipsing variable. This was
confirmed later in 1973 when Scarfe and Barlow (1974) followed
the star through primary eclipse and calculated a time of minimum
at JD(Hel.) 2441903.8136+-0.0007, earlier than predicted on the
basis of the minima observed by both Rao and Madore and Percy
together with the period of Heard and Fernie. However it was
felt premature to adjust the period at that time.
  The period was revised to 15.27575d+-0.00010d by Mayer et al..
(1978) whose observations covered the egress from primary
eclipse. Recently a revised period of 15.2756d+-0.0001d, based
upon a time of minimum obtained in 1975, was given by Scarfe
(1979) as part of a progress report on NY Cephei. The revised
periods do not differ significantly either from each other or
from the spectroscopic value, but both reduce the latter's
uncertainty by an order of magnitude.
  We have observed another primary eclipse of NY Cephei at
the University of Victoria Observatory on the night of 1980

October 2-3 under fairly good sky conditions. The observations
give a time of minimum light at JD(Hel.) 2444515.9630+-0.0008
by the method of Kwee and van Woerden (1956), about 30 min.
later than predicted by the ephemeris of Scarfe. Combining
this result with the 1973 time of minimum yields another
slightly revised period of 15.275727d+-0.000006d, but further
reduces the uncertainty by another order of magnitude. A
plot of all V observations within 0.25d of primary eclipse
obtained at this Observatory and those of Mayer et al.,according
to the ephemeris
   Time of Pri. Min.= JD(Hel.) 2441903.8136+-15.275727E,
show all the data to be consistent with this period.





                    D.J. BARLOW and D.W. FORBES
                    University of Victoria Observatory
                    Victoria, B.C. Canada V8W2Y2










References:
Heard, J.F. and Fernie, J.D. 1968, J.R.A.S. Canada 62, 99. [BIBCODE 1968JRASC..62...99H ]
Kwee, K.K. and van Woerden, H. 1956, B.A.N. 12, 327. [BIBCODE 1956BAN....12..327K ]
Madore, K. and Percy, J.R. 1973, P.A.S.P. 85, 319. [BIBCODE 1973PASP...85..319M ]
Mayer, P., Grubic, N. and Muminovic, M. 1978, I.B.V.S. 1523.
Rao, N.K. 1972, P.A.S.P. 84, 563. [BIBCODE 1972PASP...84..563K ]
Scarfe, C.D. 1979, J.R.A.S. Canada 73, 258. [BIBCODE 1979JRASC..73..258S ]
Scarfe, C.D. and Barlow, D.J. 1974, J.R.A.S. Canada 68, 96. [BIBCODE 1974JRASC..68...96S ]