COMMISSION 27 OF THE I.A.U.
              INFORMATION BULLETIN ON VARIABLE STARS
                           Number 1231

                                                    Konkoly Observatory
                                                    Budapest
                                                    1977 January 24


             NN CEPHEI AND PP LACERTAE

NN Cephei and PP Lacertae, catalogued as RR ? in the Second 
Supplement to the Third Edition of the General Catalogue of 
Variable Stars (1974), are in fact two eclipsing binaries.

NN Cep = HD 217796

From 20 May to 6 August 1976, R. Rolland followed continuously
this star, performing 751 visual estimations with binoculars.
The resulting light-curves have revealed the eclipsing binary
character of NN Cep, previously known as a spectroscopic binary.
The period was found to be 2.058 days.
    The best observed minima obtained by Rolland are listed below.
Reductions were made using the tracing paper method.

    JD 2442 919.49  Minimum II   O-C = + 0.05 d
            922.51           I         - 0.02
            991.49          II         + 0.02
            994.56           I         + 0.00

The O-C values refer to this calculated ephemeris

    Min I = JD hel. 2442959.57 + 2.058 * E
                           +-7     +-2

    The shape of the mean light-curve suggests that NN Cep is a
Beta Lyrae system rather than an EA type variable.

PP Lac = CSV 8787

From 29 August to 17 October 1976, A. Figer made 228 visual 
estimates of PP Lac on 9 nights with a 10 inch-reflector.
The light-curves show that PP Lac is a new EW type variable with
a period of 0.4011 day.
   Times of the best observed minima, obtained using the tracing
paper method are listed below:

JD hel.2443023.391   O-C = + 0.005 d
           040.434         + 0.001
           040.625         - 0.008
           050.442         - 0.018
           068.320         + 0.011
           068.516         + 0.007
           069.312         + 0.000

   The O-C values refer to either one of these calculated 
ephemerides, since the precision of the mean light-curve does not
allow us to discriminate the primary minimum from the secondary
one:

      Min I = JD hel. 2443050.46 + 0.4011 * E
                             +-2      +-4

      Min I = JD hel. 2443050.66 + 0.4011 * E
                             +-2      +-4



                                         A. FIGER
                                         R. ROLLAND

                                            GEOS
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                                         F-75014 Paris