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\IBVShead{4850}{16 February 2000}

\IBVStitle{HD 152569: A Reclassified $\boldmath\delta$ Scuti Variable}


\IBVSauth{Kaye, A.B.$^1$; Henry, G.W.$^2$; RODR\'{I}GUEZ, E.$^3$}

\IBVSinst{Applied Physics Division, Los Alamos National Laboratory, Mail Stop F-663, Los Alamos, New Mexico,\\ \indent 87545 USA; e-mail: kaye@lanl.gov}
\IBVSinst{Center of Excellence in Information Systems, Tennessee State University, 330 10th Avenue North, Nashville,\\ \indent Tennessee, 37203 USA; e-mail: henry@schwab.tsuniv.edu}
\IBVSinst{Instituto de Astrof\'{\i}sica de Andalucia, CSIC; e-mail: eloy@iaa.es}

\SIMBADobjAlias{HD 152569}{BD-01 3268}

\begintext

The F0~{\sc iv}n star HD 152569 is listed as a bona fide $\gamma$
Doradus variable by Kaye et al.\ (1999). The $\gamma$ Doradus stars
have spectral types near F0 and low-amplitude photometric variability
with periods between about 0.5 and 3 days. The inclusion of HD 152569
in this list was based on photometric variability reported by Kaye
(1998). Based on the 1997--8 data set presented here, he found a
period of $0\fday 8116 \pm 0\fday 0002$, but noted severe aliasing
difficulties.

We have acquired an additional season of data with the same 0.4-meter
automatic photoelectric telescope (APT) used for the earlier
observations. Additionally, we have obtained two nights of
Str\"{o}mgren data with the 0.9-meter telescope and six-channel
photometer at the Sierra Nevada Observatory (OSN). We used the
comparison star HD 151900 (F1~{\sc iii-iv}) and the check star HD
155646 (F6~{\sc iii}) for all observations. Differential magnitudes
were corrected for extinction and transformed to their respective
standard systems. The observations are summarized in Table 1.

\begin{table}[b]
\caption{Observations of HD 152569.}
\begin{center}
\begin{tabular}{ccccc}
\hline
\lower6pt\hbox{Year} & Date Range & \lower6pt\hbox{Telescope} & \lower6pt\hbox{Filter} & \lower6pt\hbox{$N_{\rm obs}$} \\[-3pt]
 & ${\rm HJD} - 2450000$ & & & \\
\hline
1997--8 & 486 -- 643 & 0.4-m APT & $V$ & 185 \\
 & & & $B$ & 190 \\
1998--9 & 847 -- 998 & 0.4-m APT & $V$ & 157 \\
 & & & $B$ & 156 \\
1999 & 1388 -- 1389 & 0.9-m OSN & $ubvy-\beta$ & 111 \\
\hline
\end{tabular}
\end{center}
\end{table}

Up to five observations were acquired with the APT each night, spaced
at roughly two hour intervals, resulting in severe aliasing problems
when analyzed alone. However, when combined with the OSN data
containing 50--60 points per night, least squares analysis using the
Vani\v{c}ek method (1971; via a {\sc fortran} code provided by
L.\ Mantegazza) revealed a primary periodicity of $0\fday 075401 \pm
0\fday 000001$ and an amplitude of $11.4 \pm 0.7$ mmag in the combined
$V+y$ observations. The resulting least-squares spectrum is shown in
Figure~1. The data are shown phased with the principle period from
Fig.~1 in Figure 2.

\IBVSfig{10cm}{4850-f1.ps}{Least-squares spectrum of the $V+y$ data of HD
152569 showing the principle peak at $\nu = 13.26$~d$^{-1}$ ($P =
0\fday 075$). Treating this frequency as a ``known constituent'', no
signals remain above the 0.10 reduction factor level.}

\IBVSfig{10cm}{4850-f2.ps}{Phased light curve of the $V+y$ data 
of HD 152569.}

The 0.81-day period reported earlier is an alias of the true 0.075-day
period. Based on this revised period, we conclude that HD 152569 is
{\it not} a $\gamma$ Doradus variable but {\it is} a very low-amplitude
$\delta$ Scuti star.

\bigskip

Kaye's work was done under the auspices of the U.\ S.\ Department of
Energy at the Los Alamos National Laboratory under contract
No.\ W-7405-ENG-36. Astronomy with automated telescopes at Tennessee
State University is supported through NASA grant NCC5-228 and NSF grant
HRD-9706268.

\references

Kaye, A.B., 1998, Ph.D. Dissertation, Georgia State University

Kaye, A.B., Handler, G., Krisciunas, K., Poretti, E., \& Zerbi, F.M., 1999, {\it PASP}, {\bf 111}, 840

Vani\v{c}ek, P., 1971, {\it Ap\&SS}, {\bf 12}, 10

\endreferences

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