COMMISSIONS 27 AND 42 OF THE IAU
                INFORMATION BULLETIN ON VARIABLE STARS
                             Number 4013

                                                 Konkoly Observatory
                                                 Budapest
                                                 15 April 1994

                                                 HU ISSN 0374 - 0676


       DISCOVERY OF 6.2-MINUTE OSCILLATIONS IN THE Ap Sr STAR HD 86181

 Martinez (1993) has obtained Stromgren photometry for all the Ap SrCrEu stars in the
first four volumes of the Michigan Spectral Catalogue, along with selected stars classified
by Bidelman & MacConnell (1973) north of declination -12deg. Using this 
photometry we
have been conducting a systematic survey for new rapidly oscillating Ap (roAp) stars. In
this note we announce the 12th one found as part of the survey, the 27th now known.
  HD 86181 was classified as Ap Sr by Houk & Cowley (1975). Martinez (1993) measured
V=9.323, b-y=0.172, m_1=0.205, c_1=0.757 and Beta=2.819. The calculated dereddened
metallicity and luminosity indices are [delta m_1]=-0.030 and [delta c_1]=-0.095, both of which
indicate strong metallicity and heavy line-blocking in the Stromgren v band, characteristics
we have come to associate with roAp stars.
  On the night of 11/12 March 1994 we obtained 4.85 hours of continuous 10-s 
photometric integrations of HD 86181 through a Johnson B filter using the 0.5-m. telescope of
the Sutherland Station of the South African Astronomical Observatory. The observations
were corrected for coincidence losses, sky brightness, extinction and reduced to 40-s 
integrations. Figure 1 shows a two-hour section of the light curve for that night and Figure
2 shows the amplitude spectrum of the entire 4.85-hr light curve. The 6.2-min oscillations 
are obvious in both. No comparison star was used, but sky transparency variations,
scintillation, and photon statistics produced noise of a maximum amplitude of about 0.35
mmag at the frequencies of interest, as can be seen in the amplitude spectrum.
  We are continuing observations of this star and, as of this writing, have 24 hours of
observations obtained on 6 nights. The amplitude of the light curve is modulated. The
star is multiperiodic and may also show rotational amplitude modulation.


                           [FIGURE 1]
                           [FIGURE 2]


                          D. W. KURTZ
                          Peter MARTINEZ
                          Department of Astronomy
                          University of Cape Town
                          Rondebosch 7700
                          South Africa



References:
Bidelman, W. P., MacConnell, D. J., 1973, A.J., 78, 687 [BIBCODE 1973AJ.....78..687B ]
Houk, N. & Cowley, A. P., 1975, Michigan Spectral Catalogue, Vol. 1, 
   Department of Astronomy, University of Michigan, Ann Arbor [BIBCODE 1975mcts.book.....H ]
Martinez, P., 1993, Ph. D. Thesis, University of Cape Town [BIBCODE 1993PhDT.......246M ]