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\IBVShead{4224}{10 August 1995}

\title{1995 PHOTOMETRY OF RT ANDROMEDAE}

\begintext

	RT Andromedae (=BD\,+52\degr 3383A=\#201 in the catalog of Strassmeier 
et al. 1993) is a member of the short period eclipsing group of RS CVn stars.  
Budding and Zeilik (1987) first modeled the spots on this star.  Zeilik et al. 
(1989) modeled the spot structure for available data from 1920 to 1989.  This 
work builds on previous work by modeling the spot structure during 1995.

	I observed RT And on the nights of 18 January and 2, 3, 4, 6, 7, and 20 
February 1995 using the San Diego State University 61-cm telescope on Mt. 
Laguna.  The telescope is equipped with a photometer using a Hamamatsu R943-02 
tube operated at $-$1450V and cooled to $-$15\degr C.  The BVRI filters are 
chosen to closely match the Johnson--Cousins system.  The comparison star was 
BD\,+52\degr 3384 (=SAO\,35208).  In January 1994, I calibrated the magnitudes 
of this comparison star using Landolt standards.  I got:  U=10.96, B=10.25, 
V=10.12, R=10.05, and I=9.99.  Because February is rather late in the observing 
season for RT And I was only able to observe it for a short time each night. 
The light curves therefore contain significant gaps at the beginning of the 
secondary eclipse and at third quadrature.  The data however are sufficient to 
model the spots.  The data, plotted in Figures 1 and 2, are differential 
magnitudes (star--comparison) in the standard Johnson--Cousins system.

	To model the data, I used the Information Limit Optimization Technique 
(ILOT) described in detail by Budding and Zeilik (1987).  To perform the initial
fits, I started with the orbital parameters found by Zeilik et al. (1989), 
including ellipticity effects.  Unlike most of the short period RS CVns, RT And 
has an elliptical orbit.  From the initial binary star fits, I extract a 
distortion wave and then fit the distortion wave for the longitude and radius 
of circular spots at 0K.  The ILOT allows fitting for the spot latitude, but in 
this case I was unable to fit for the latitude simultaneously with the other 
parameters.  I therefore used a fixed latitude of 45\degr, the value to which 
the latitude seemed to converge in preliminary trial fits.  The fits for each 
wavelength are performed independently.  I get:
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\begin{tabular}{lllll}
\hline
	&B band	&V band	&R band	&I band\\
\hline
\\
Longitude&110.9$\pm$5.1	&112.7$\pm$5.2&	117.9$\pm$5.6&	125.2$\pm$4.86\\
Latitude&45&45	&45&	45\\
Radius&	11.5$\pm$0.7&	12.0$\pm$0.7&	11.3$\pm$0.8&	12.0$\pm$0.7\\
${\chi}^{2}$&110.6	&82.3&	70.2&	135.1\\
\hline
\end{tabular}
\end{center}
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\centerline{2}
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\centerline{Figure 1}
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\centerline{\epsffile{4224-f2.ps}}
\centerline{Figure 2}
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\centerline{3}
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\centerline{\epsffile{4224-f3.ps}}
\centerline{Figure 3}
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\centerline{\epsffile{4224-f4.ps}}
\centerline{Figure 4}
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\centerline{4}
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	Figures 3 and 4 show the initial and spot fits in the V band.  I made no
attempt to do clean fits to remove the spot effects and find the binary star 
parameters because the incompleteness of the light curves would reduce the 
confidence in these solutions.  Because there is a gap in the light curves at 
roughly longitude 270\degr\ it is not possible to completely rule out the 
possibility of a spot at this longitude.  To investigate this possibility I 
tried to fit both a single spot and a second spot at this longitude.  In 
neither case was I able to fit a spot, so the available data indicates that 
RT And has a single spot in the 90\degr Active Longitude Belt.  This result is 
similar to the previous long term trends found by Zeilik et al. (1989) for a 
single spot in one of two Active Longitude Belts.
\vskip 4mm
	I thank Ron Angione for scheduling very generous amounts of observing 
time at Mt. Laguna.  I received support from the American Astronomical Society 
Small Grants Program for this work.  I also acknowledge both financial support 
and a Faculty Scholarly Development Assignment Program Leave from Western 
Carolina University.
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\beginauthors
\authorsrightcol
P.A. HECKERT
Dept. of Chem. \& Physics
Western Carolina University
Cullowhee, NC 28723   
USA
\endauthors

\references

Budding, E. and Zeilik, M., 1987, {\it Astrophys. J.}, {\bf 319}, 827

Strassmeier, K. et al., 1993, {\it Astron. \& Astrophys. Suppl.}, {\bf 100}, 173

Zeilik, M., Cox, D.A., De Blasi, C., Rhodes, M., and Budding, E., 1989, {\it Astrophys. J.}, {\bf 345}, 991
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