COMMISSION 27 OF THE I. A. U,
         INFORMATION BULLETIN ON VARIABLE STARS
                     Number 1820

                                    Konkoly Observatory
                                    Budapest
                                    1980 July 23


          HR 3593, A NEW BRIGHT beta CEPHEI STAR



  HR 3593 (HD 77320, BD-42.4875) is a 6th magnitude star
classified B2Vnn(e) by Houk [1978). The star has been measured
more than 400 times in the Geneva photometric system from the
Swiss station of La Silla Observatory, Chile, between 1975.9
and 1980.3. The mean apparent magnitudes in the seven filters
of the Geneva system, with their standard deviations, are the
following:


Filter                  U      B1      B      B2     V1    V     G
lambda_o[Angstr.]      3456   4024    4245   4480   5405  5500  5805
Mean magnitude         5.321  5.673   4.889  6.486  6.727 6.040 7.257
Standard dev.          0.033  0.028   0.027  0.028  0.026 0.026 0.026


   From the values of the standard deviations we see that the
star is variable and that the amplitude of variation is almost
the same in the whole optical range (a slightly larger amplitude
in the U filter can even be noted).

  The light variation of HR 3593 has been recorded during
several nights. Figures 1 to 3 give three examples of variations
in the V magnitude. On the basis of the data obtained during
the two consecutive nights (Figures 1 and 2), a period of about
7 h can be derived. However, the light curve shown in Figure 3
is quite different (value of the maximum and shape). Thus,
at least two frequencies are necessary to describe the observed
light variations.

  On the basis of its spectral type and because of the
existence of a beat phenomenon in the light curve, we can
state that HR 3593 is a new beta Cephei star. The amplitude of

                  [FIGURE 1]
                  [FIGURE 2]
                  [FIGURE 3]

the light variation (Delta V = 0m1) is among the largest and the
period (P = 7 h) could be the longest presently known for this
class of pulsating stars (cf. Lesh and Aizenman, 1978).

  In order to determine the various frequencies of the
pulsation, it is necessary to follow continuously several
successive cycles. Such a program requires cooperation between
various observatories in the Southern hemisphere, located
on sites sufficiently remote from each other.




                 G. BURKI, M. BURNET, F. RUFENER
                     Geneva Observatory
                     CH-1290 Sauverny/Switzerland




References:
Houk,N.: 1978,Michigan Catalogue, vol. 2, University of
     Michigan, Ann Arbor [BIBCODE 1978mcts.book.....H ]
Lesh, J.R., Aizenman, M.,: 1978, Ann.Rev.Astron.Astrophys.
      16, 215 [BIBCODE 1978ARA&A..16..215L ]