COMMISSION 27 OF THE I.A.U.
              INFORMATION BULLETIN ON VARIABLE STARS
                           Number 1258

                                                    Konkoly Observatory
                                                    Budapest
                                                    1977 March 31


         ON THE NON-VARIABILITY OF BD +74d877

Since Archer's (1959) observations in 1958, BD +74d877
(HD 197617) was thought to be the brightest (mpv=8.5), ultrashort
period eclipsing binary known. In the Finding List by Koch et al.
(1963) it is assigned a period of 0d.1846, a spectral type of A2,
and primary and secondary depths of 0.3m and 0.2m, respectively.
Koch (1963), van Agt and van Genderen (1963), and Hall (1967)
observed BD +74d877 photoelectrically but were unable to find
any significant variability. Although these negative results are
moderately convincing, interest in the star has been renewed be-
cause of the superficial resemblance to some post nova or neutron
star systems. Further, the light curve observed by Archer (1959),
shown in Figure 1, is compelling. The purpose of this note is to
exhibit the most convincing set of observations, showing BD +74d877
to be nonvariable, and to develop an argument that Archer's 
observations were spurious.
   This writer obtained simultaneous yellow and blue photoelectric 
observations of the system on October 4-5, 1976 with the
Pennsylvania State University 60-inch reflector. Measurements
were made with a 1 second time constant for a duration (0.20d)
somewhat longer than the listed period of the system, and alternated 
between BD +74d877 and the comparison star BD +74d878. The
56 observations of BD +74d877, shown in Figure 2, and BD +74d878
exhibit no variations greater than 0.02m.
   A detailed examination of Archer's observations (Figure 3)
reveals that almost all the observational weight is in the data
for March 16-17, 1958. The remaining two nights show no convincing 
variations, and if it were not for six observations, minima
would not be describe at all.
   It is interesting to reconsider the evidence which caused
BD +74d877 to be described as a variable in the first place.
Archer (1958,1959) had been observing several short period variable 
stars around the time of his observations of BD +74d877
namely VW Cep (P = 0.2783d) and VY Leo (P = 0.1288d). The data for
March 16-17 show an unusual circumstance. On March 14-15 and
March 19-20 observations of BD +74d877 were interlaced with
VW Cep and their common nearby comparison star, BD +75d7553.
However, on March 16-17 no observations were published for VW Cep
but yet there time slots interlaced for it. It is suggested that
there may have been something unsuitable about the VW Cep data
caused by instrumentation or sky problems, and that this also
produced the largest scatter in the March 16-17 data of BD+74d877.
   In view of all the evidence it seems certain that BD+74d877
should be relegated to the class of a normal, single A2 star.


                                    LOUIS WINKLER

                               Department of Astronomy
                          The Pennsylvania State University
                             University Park, Pa. 16802



References:

van Agt, S.L.Th.J. and A.M. van Genderen 1963, B.A. IV, 17, 250 [BIBCODE 1963BAN....17..250V ]
Archer, S. 1958, J.B.A.A., 68, 269
Archer, S. 1959, ibid, 69, 38
Hall, D.S. 1967, I.B.V.S., No. 231
Koch, R.H. 1963, A.J., 68. 620 [BIBCODE 1963AJ.....68..620L ]
Koch, R.H., Sobieski, S. and Wood, F.B. 1963, Publ. Univ. Penna. (Astr. Ser.) 9



                            [FIGURE 1]

   Figure 1: Archer's light curve of 1958

                            [FIGURE 2]

   Figure 2: Observations in 1976

                            [FIGURE 3]

   Figure 3: Archer's individual nights