COMMISSION 27 OF THE I.A.U.
              INFORMATION BULLETIN ON VARIABLE STARS
                           Number 1257

                                                    Konkoly Observatory
                                                    Budapest
                                                    1977 March 29


          HD 153747: A DELTA SCUTI VARIABLE

HD 153747 (HD spectral type B9) was discovered to show
light variations when observed by McKay at Mount John University
Observatory on April 2, 1973. The star was found to show periodic 
variations of close to 0.04m and had a period of about 70 minutes. 
The amplitude was found to be variable.
   The star has been observed photoelectrically during 1976
in the B and V bands of the UBV system with the 60 cm telescope
at Mount John University Observatory. A thermoelectrically cooled 
EMI 6094B photomultiplier tube was used for the observations.
Extinction was determined nightly and the observations have been
reduced to the UBV system. The comparison stars used were
HD 153426 and HD 153767. Each observation consists of four 10
second integrations.
   Observations obtained during 1976 have not shown evidence
of large amplitude changes. However, observations obtained at
Mount John University Observatory prior to 1976 have shown a
range of amplitude variation from less than 0.02m to 0.10m.
   A section of the observations obtained on 13th June, 1976
are given. The comparison star used was HD 153426. From Fourier
analysis by the method of Valtier (1972), P=0.0496 days and
Amp.= 0.016m from the observations for the whole night of 13th
June.
   It is felt that the HD spectral type may be too early for
this star. A median (B-V) =0.11m, V=7.41 has been obtained from
observations including the E region standards. This value is
uncorrected for reddening.
   The period and colour of HD 153747 is suggestive of it
being a hot delta Scuti star and it fits the definition of these
variables given by Baglin et al. (1973). Using the period-luminosity 
relationship of Dworak and Zieba (1975) for bright delta Scuti
stars, an absolute visual magnitude of +0.5m was derived implying
a distance modulus of 6.9m. Using the galactic reddening data of
Fitzgerald (1968) for a star of distance 240pc and l^II=347d08',
b^II=1d57' a reddening of 0.08m is obtained. The unreddened median
(B-V) would then be 0.03m corresponding to a mean spectral type
of about A1. The HD spectral type of B9 would require a B-V of
about -0.06m and this classification may therefore be too early.
   A spectrum obtained on 103aO emulsion at 60A/mm at Mount
John University Observatory on the 14th August, 1976, showed an
early A type spectrum compatible with (B-V) = +0.03m, and not of
late B type.
   Further analysis of the light variations is to be carried
out and will be published elsewhere.

                          [FIGURE 1]

   The light curve of HD 153747. Each point represents a single
magnitude difference in the sense variable minus comparison.


                                     C.J. McINALLY
                                     B.J. McKAY

                             Mount John University Observatory
                               Lake Tekapo, New Zealand



References:

Baglin et al., 1973, Astron. Astrophys., 23, 221 [BIBCODE 1973A&A....23..221B ]
Dworak, T.Z. and Zieba, S., 1975, IBVS, No. 1005
Fitzgerald, M.P. 1968, Astron. J., 73, 983 [BIBCODE 1968AJ.....73..983F ]
Valtier, J.C., 1972, Astron. Astrophys., 16, 38 [BIBCODE 1972A&A....16...38V ]