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\IBVShead{4826}{7 January 2000}

\IBVStitle{HD 209775: A New {\boldmath $\delta$} Scuti Variable}

\IBVSauth{Henry, G.W.; Henry, S.M.}

\IBVSinsto{Center of Excellence in Information Systems, Tennessee State 
University, 330 10th Ave. North, Nashville,\\ \indent Tennessee 37203, U.S.A., e-mail: henry@schwab.tsuniv.edu, henrysm@galileo.tsuniv.edu}

\SIMBADobjAlias{HD 209775}{BD+16 4660}
\IBVStyp{ DSCT }
\IBVSkey{photometry}
\IBVSkey{delta Scuti variable}

\begintext

In the course of making photometric observations of planetary transits
in HD~209458 (Henry et al.\ 1999; 2000), we found one of our comparison stars, HD~209775, to be a new small-amplitude variable. Very little has been published about HD~209775; Olsen (1980) estimated a spectral type of Am/p based on his Str\"{o}mgren $uvby$ photometry and the assumption that his Str\"{o}mgren indices were not contaminated by duplicity. Fehrenbach \& Burnage (1982) found the radial velocity to be constant to 2.6 km s$^{-1}$ in six measurements. The {\it HIPPARCOS} catalogue classifies the star as photometrically constant and gives $V = 7.56$, $B-V = 0.33$, and 
$\pi = 10.17$ mas (Perryman et al.\ 1997). Combined with the effective 
temperature calibration of Flower (1996), the {\it HIPPARCOS} results imply 
an absolute magnitude of 2.50 and a spectral type of F0~V.

\IBVSfig{8cm}{4826-f1.ps}{Johnson $B$ photometry over two nights acquired
with a 0.40~m APT showing HD 209775 to be a new low-amplitude, short-period
variable star.}

Figure~1 plots our Johnson $B$ photometry acquired with the T3 0.40~m 
automatic photoelectric telescope (APT) located at Fairborn Observatory 
in southern Arizona. We used HD~209458 ($V = 7.65$, $B-V = 0.594$, G0~V) as 
a comparison star to compute the differential magnitudes since it has been 
shown to be constant to 0.0017~mag or better except during transits (Henry et al.\ 2000). The observations were corrected for differential extinction and 
transformed to the standard Johnson system. Details on the operation of the 
APT and the reduction and precision of the data can be found in Henry (1995).

\IBVSfig{5cm}{4826-f2.ps}{Periodogram analysis of the $B$ data gives a
period of $0.0608 \pm 0.0002$~d and a full amplitude of $0.012 \pm 0.001$~mag.}

The results of periodogram analysis of the $B$ observations from Figure~1 are shown in Figure~2. We find a period of $0.0608 \pm 0.0002$~d. A least-squares sine fit to the $B$ data at this period gives a full amplitude of $0.012 \pm 0.001$~mag. From the $V$ observations, we find a period of 
0.0607~$\pm$~0.0002~d and an amplitude of 0.007~$\pm$~0.001~mag. 
The star lies in the region of the HR~diagram where the $\delta$ Scuti 
and the $\gamma$ Doradus variables overlap (Handler 1999). Its
short period places it in the $\delta$ Scuti class.

Astronomy with automated telescopes at Tennessee State University is
supported through NASA grants NCC5--96 and NCC5--228, which funds the Center
for Automated Space Science, and NSF grant HRD--9706268, which funds the
Center for System Science Research.

\references

Fehrenbach, C., \& Burnage, R., 1982, A\&AS, 49, 483

Flower, P. J., 1996, ApJ, 469, 355

Handler, G., 1999, MNRAS, 309, L19

Henry, G. W., 1995, ASP Conf. Ser., 79, 44, in Robotic Telescopes: Current Capabilities, Present Developments, and Future Prospects for Automated Astronomy, eds.\ G. W. Henry and J. A. Eaton (ASP: San Francisco)
%Changed: Fri Jun  3 09:48:10 MEST 2005

Henry, G. W., Marcy, G. W., Butler, R. P., \& Vogt, S. S., 1999, IAU Circular No.\ 7307

Henry, G. W., Marcy, G. W., Butler, R. P., \& Vogt, S. S., 2000, ApJ, 529, L41

Olsen, E. H., 1980, A\&AS, 39, 205

Perryman, M. A. C., et al., 1997, The Hipparcos and Tycho Catalogues (ESA: The Netherlands)

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