COMMISSION 27 OF THE I. A. U.
           INFORMATION BULLETIN ON VARIABLE STARS
                        Number 3321

                                            Konkoly Observatory
                                            Budapest
                                            21 April 1989

                                            HU ISSN 0374 - 0676


               HD 17978: A NEW DELTA SCUTI VARIABLE*


HD 17978 is a 9.9 magnitude A2 star in the constellation Fornax. We used it as
a comparison star in a photometric program, carried out in 1986 with the uvby
photometer attached to the Danish 50 cm telescope. Ten observations made on
two nights, November 29 and 30, indicate that HD 17978 is a small amplitude
variable. Since we do not plan to observe the star in the future, we present
here a brief account of the data we collected.


                             [FIGURE 1]

 Figure 1. The differential b magnitudes of HD 17978 (upper panel) and
 of the comparison star (lower panel) plotted as a function of phase
 of the 0.0577 day period. Zero phase corresponds to JDhel 2446750.


The period of the variation is short, certainly shorter than three hours.
Unfortunately, it cannot be uniquely determined from our scarce data. Figure 1
(upper panel) shows the differential b magnitudes of the star in the sense "HD
17978 minus the mean of HD 18225 and HD 18100" phased with a period of 0.0577
days, which is one of the series of possible values. Zero phase corresponds to
JD_hel 2446750. The differential magnitudes "HD 18225 minus HD 18100" are
plotted in the lower panel of the figure. The sine curve (solid line) fitted
to the variable star data by the method of least squares has an amplitude (half
range) of 0.0094+-0.0012 mag. The maximum occurs at phase 0.460+-0.020.
Standard deviation of the fit amounts to 0.0026 mag. This can be compared with
0.0022 mag, the standard deviation with which the mean level line (horizontal
straight line in the lower panel) fits the comparison stars' data. The
amplitudes in u, v, and y amount to 0.0072+-0.0019 mag, 0.101+-0.0017 mag,
0.0073+-0.0020 mag, respectively, and the phases of maximum in these bands do
not differ significantly from the phase of maximum in b.

The time scale and the amplitudes of the light variation of HD 17978, together
with its spectral type of A2, indicate that the star is a delta Scuti variable.



C. STERKEN                   M. JERZYKIEWICZ
Astrofysisch Instituut       Wroclaw University Observatory
Vrije Universiteit Brussel   ul. Kopernika 11
Pleinlaan 2                  51-622 Wroclaw
1050 Brussel                 Poland
Belgium

* Based on observations collected at the European Southern Observatory,
  La Silla, Chile