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\IBVShead{4358}{31 July 1996}


\centerline{\ft U,B,V LIGHT CURVES AND PERIOD BEHAVIOR FOR} 
\centerline{\ft THE SOLAR-TYPE ECLIPSING BINARY, V417 AQUILAE}
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\begintext

    As a part of our continuing study of short period, solar-type binaries, we 
have obtained well-covered UBV light curves of V417 Aquilae [$\alpha$(2000) = 
19\fh 35\fmm 24\fss 1, $\delta$(2000) = 5\degr 50'17'', GSC\,4904.531, PPM\,168201, BD\,+05\degr 4202].  V417 
Aql was discovered by Hoffmeister (1935).  Soloviev (1937) classified it as a W 
UMa variable, gave 4 times of minimum light, and found it to have a period of 
0\fd 37.  One set of B, V light curves, formed from normal points, has been 
published (Faulkner 1983).  A later paper (Faulkner 1986) gave the following 
improved  ephemeris:
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\hspace*{25mm}JD Hel Min.\,I = 2445554.7240 + 0\fd 37031142 $\times$ E \hfill        (1)     
\hspace*{77mm}  $\pm$  1     \hspace*{14mm}\ $\pm$ 30  
                                                  
\vskip 2mm

Some 70 epochs of minimum light are available in the literature, including four 
photoelectric timings by Agerer and H\"ubscher (1995), six by Faulkner (1983, 
1986), and many visual/photographic  timings by BAV members (see, for instance, K\"amper 1984).  

    Our present observations were obtained from July 19 to 24, 1995 at Lowell 
Observatory in Flagstaff, Arizona.  A thermoelectrically cooled EMI\,6256S (S-13 cathode) PMT was used in conjunction with the 0.78-m Lowell  reflector.   A  
finder chart  is included as Figure 1.   The variable is denoted as ``V" while 
the comparison [$\alpha$(2000) = 19\fh 34\fmm 55\fss 8, $\delta$(2000) = 5\degr 47'36''] and check [$\alpha$(2000) = 
19\fh 35\fmm 30\fss 8, $\delta$(2000) = 5\degr 44'27''] stars are denoted as ``C" and ``K", 
respectively.  About 850 observations were taken in each passband.

    Seven mean epochs of minimum light were determined from the observations 
made during two primary and five secondary eclipses using bisection of chords.  
These  minima are given in Table 1 accompanied by their probable errors in 
parentheses.  

     Inspection of the O$-$C residuals of a full linear fit to all the timings 
revealed two eras of constant, but different, periods connected by what may be  
a smooth transition (see Figure 2).   We calculated a period of 0\fd 3703142(2) for the first 
era (before JD\,2433000) and the following improved ephemeris for the modern era:
 \vskip 2mm    
  \hspace*{25mm}JD Hel Min.\,I = 2449546.4979 + 0\fd 3703119 $\times$ E \hfill (2)
   \hspace*{77mm}                $\pm$11     \hspace*{15mm}$\pm$ 1
\vskip 2mm

    The data indicates a period change $\sim$$-$0\fss 16, statistically significant at 
the 12$\sigma$ level.  We find that our identification of primary and secondary 
eclipses are reversed relative to those in recent publications.   This is not 
surprising since the eclipse depths are nearly equal.
    
The linear ephemeris for late timings (equation 2) was used to calculate 
the O$-$C residuals in Table 1 and the phases of the present observations.  
More timings of minimum light are needed, both from photographic archives and 
future observations.
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\centerline{2}
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\begin{center}Figure 1. Finding chart (modified from a Digitized Sky Survey
image) of V417 Aql (V), the comparison star (C), and the check star(K)
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\centerline{\epsffile{4358-f2.ps}}
\begin{center}Figure 2. O$-$C residuals for all available times of minimum
light as calculated from equation 2
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\centerline{3}
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\begin{center}Figure 3. U light curve and U$-$B color curve for V417 as
magnitude differences, variable minus comparison star
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\centerline{\epsffile{4358-f4.ps}}
\begin{center}Figure 4. B and V light curves and B$-$V color curve for V417 
Aql as magnitude differences, variable minus comparison star
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\centerline{4}
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\centerline{Table 1. Epochs of Minimum Light, V417 Aquilae}
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\begin{center}
\begin{tabular}{lcrcc}
\hline
    JD Hel.& & & & \\
    2449000+         &  Min&   Cycles&  (O-C)&   Source\\
\hline
\\          
    546.4979(5) &   I &    0.0 &    $-$0.0003 & AH\\
    917.9200(6) &   I & 1003.0 &    $-$0.0010 & PO\\
    918.8454(7) &  II & 1005.5 &    $-$0.0014 & PO\\
    919.9563(6) &  II & 1008.5 &    $-$0.0014 & PO\\
    920.6964(9) &  II & 1010.5 &    $-$0.0020 & PO\\
    920.8826(10)&   I & 1011.0 &    $-$0.0009 & PO\\
    921.8081(5) &  II & 1013.5 &    $-$0.0012 & PO\\
    922.9183(3) &  II & 1016.5 &    $-$0.0019 & PO\\
\hline
\end{tabular}
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\normalsize

\centerline{Sources:  AH:  Agerer and H\"ubscher (1995), PO:  present
    observations}
\large
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        The U, B, V  light curves and U$-$B, B$-$V color curves of V417 Aql, as 
defined by their individual observations,  are shown in Figure 3 and 4 as 
differential standard magnitude (variable--comparison) versus phase.  Our light 
curve solutions reveal that V417 Aql is a W-type W UMa binary with a mass ratio 
of 0.37, and a fill-out of 19\%.   A total eclipse of $\sim$25 min duration occurs in 
the primary minimum.  Reductions and analyses were largely done by BP as a 
part of her spring and summer undergraduate research project at Millikin 
University.  RGS and BC acted as her advisors.

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\beginauthors
BRANDY PAULEY                            
BRIAN  CARRIGAN, JULIE FRENCH$^{\star}$              
MIIN LOOI$^{\star}$                                  
Millikin University                         
Decatur, IL 62522 USA                       
\authorsrightcol
RONALD G. SAMEC$^{\star}$    
Bob Jones University        
Greenville, SC 29614 USA 
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\endauthors
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$^{\star}$ Visiting astronomer, Lowell Observatory, Flagstaff, Arizona, USA
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\references

Agerer F., and H\"ubscher J.,  1995,  {\it IBVS}, No.\,4222

Faulkner, D. R.,  1983, {\it IBVS}, No.\,2439

Faulkner, D. R.,  1986,  {\it PASP}, {\bf 98}, 690

Hoffmeister, C., 1935, {\it AN}, {\bf 255}, 403

K\"amper, B.-C.,  1984, {\it BAV Rundbrief}, {\bf 33(4),} 151

Soloviev, A., 1937, {\it Tadjik Obs. Circ.}, {\bf  22}, 1

Soloviev, A., 1948, {\it The Variable Stars}, {\bf 6(5)}, 287

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