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\IBVShead{4186}{2 May 1995}

\centerline{\ft UBV LIGHT CURVES OF THE NEAR-CONTACT}
\centerline{\ft  BINARY AK CANIS  MINORIS}
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\begintext 
          

   In our study of the eccentric eclipsing binary (EEB) candidates of 
Heged\"us (1988), we obtained UBV photoelectric light curves of AK Canis 
Minoris [R.A.(2000) = 07\fh 40\fmm 15\fss 5, D.(2000) = 03\degr 57'09''].  
AK CMi (BD+04\degr 1778, 
AN310.1934, P3052, SVS 1102) was discovered by Hoffmeister (1934). 
Notni (1955) published a photographic light curve, and determined a period 
of $\sim$0.57d.  He states that the shallow secondary eclipse (we measure 
0.16 mag in B) occurred at phase 0.55.  Given the high scatter and 
the sparse coverage of his light curve, this result is highly 
questionable.  Strohmeier et al. (1957) includes a finder chart in his 
study.  Robb and Moffat (1987) give two precision epochs of primary minima 
and one of a secondary minimum.  We find that their secondary eclipse 
occurs at phase 0.46.  Shaw (1994) includes AK CMi in his list of near-contact 
binaries.  In all, some 200 timings of minimum light are found in the 
literature or in the BAV data base.  
   
The present observations were taken on 1994, February 10-15, inclusive,
at Lowell Observatory, Flagstaff, Arizona with the National Undergraduate 
Research Observatory 0.78-m reflector.  A thermoelectric cooled PMT was
used with Johnson UBV filters.  Two nearby stars were used as comparison
[R.A.(2000) = 07\fh 41\fmm 5\fss 9, D.(2000) = 03\degr 50'08''] and check 
[R.A.(2000) = 07\fh 40\fmm 18\fss 0, D.(2000) = 03\degr 52'19''].  
The comparison star was an excellent   
color match to the variable with the $\Delta$(B$-$V) and the $\Delta$(U$-$B) 
averaging $\sim$0.1 and $\sim$0.0, respectively.
 
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Figure 1. Period behavior of AK CMi as shown by the calculated from the 
quadratic ephemeris. 
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Figure 2. Light curves of AK CMi as defined by the individual observations.  
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\centerline{3}
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 Two mean epochs of minimum light were calculated from one secondary
and one primary eclipse.  The bisection-of-chords method was used.  Our
epochs were JD\,Hel.\,Min.\,I = 2449396.70325($\pm$.00046) and  
JD\,Hel.\,Min.\,II 
= 2449395.8546($\pm$.0003).  From the densely packed data of the past 23 years, we determined the following improved epemeris:
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\hspace*{2cm}JD Hel. Min I = 2449396.7075 + 0\fd 5658968$\times$E \hfill (1)
\hspace*{6.8cm}$\pm$.0018 \ \ \ \,$\pm$.0000002
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The O$-$C's calculated from this ephemeris suggest that AK CMi is undergoing
a continuous period decrease.  Because of this we calculated the quadratic
ephemeris:
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\hspace*{15mm}JD Hel. Min I = 2449396.7050 + 0\fd 5658956$\times$E $-$ 
0.00000000010$\times$E$^2$\hfill (2) 
\hspace*{6.3cm}$\pm$.0008\ \,\hspace*{3mm}$\pm$.0000002\ \ \hspace*{10mm}$\pm$.00000000002
\vskip 1mm

The O$-$C's generated from the first two terms of this equation are shown 
in Figure 1 overlain by a curve generated by the quadratic term.  In 
these calculations, we weighted the precision epochs as 1.0 and the 
photographic and visual timings as 0.1.  We used equation (1) to phase our
observations.  These equations indicate that our Min II occurred 
at phase 0.5 to within the errors.  We believe that AK CMi is not an EEB. 
The appearance of the light curves about the secondary eclipse supports 
this conclusion.        

   The light curves of AK CMi defined by the individual observations 
are shown in Figure 2 as $\Delta$ mag vs. phase.  Our preliminary light curve 
solution indicates that the components are in a near contact semi-detached
configuration with the fillout of the primary component being $\sim$80\% and a 
component temperature difference of $\sim$4100 K . The complete analysis of the 
  observations are underway and will appear elsewhere.
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\beginauthors
\authorsrightcol
RONALD G. SAMEC$^{\star}$
RICHARD J. McDERMITH
BRIAN J. CARRIGAN
Dept. of Physics and Astronomy
Millikin University
Decatur, Il 62522-2084
USA
\endauthors

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$^{\star}$ Visiting Astronomer, Lowell Observatory, Flagstaff, Arizona

\references

Heged\"us, T., 1988, {\it CDS Bulletin}, {\bf 35}, 15

Hoffmeister, C., 1934, {\it AN}, {\bf 253}, 197

Notni, P., 1955, {\it MVS}, {\bf 177}, 242

Robb, R.M. \& Moffat, J.D., 1987, {\it BAAS}, {\bf 19,} 709

Shaw, J.S., 1994,  {\it Mem. Soc. Astron. Ital.}, {\bf 65}, 95

Strohmeier, W., Kippenhahn, R., and Geyer, E., 1957, {\it Bamberg Kl. Ver\"off.}, No.\,18, 1

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