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\IBVShead{5307}{14 August 2002}

\IBVStitletl{Str\"{o}mgren Differential Photometry of the B\lowercase{e} Star}{ {\large \boldmath $\theta$} C\lowercase{r}B: 1999-2002} 

\IBVSauth{ADELMAN, Saul J.}

\IBVSinsto{Department of Physics, The Citadel, 171 Moultrie Street, Charleston,
  SC 29409, USA, \\e-mail: adelmans@citadel.edu}

\SIMBADobjAliasJ2000{tet CrB}{HR 5778}{15 32 55.78 +31 21 32.9}
\IBVStyp{ Be }
\IBVSkey{photometry}
\IBVSabs{Stromgren uvby differential photometry from the Four College} 
\IBVSabs{Automated Photoelectric Telescope of the Be star Theta CrB} 
\IBVSabs{for 1999-2002 and for five previous years show that this star has} 
\IBVSabs{remained photometrically constant between 1993 and 2002. Data from} 
\IBVSabs{other observers show constancy for an additional four years.  This is}
\IBVSabs{the longest well documented period of inactivity for this star.} 


\begintext

The Be star $\theta$ Coronae Borealis (= HR 5778 = HD 138749) has had periods 
of both activity and inactivity (see, e.g., Percy et al., 1988 and Percy \& 
Attard, 1992).  Fabregat \& Adelman (1998) and Adelman (1999) presented 
differential Str\"{o}mgren $uvby$ photometry from the Four College Automated 
Photoelectric Telescope (FCAPT) of this star from 1994 to 1999.  Neither 
short term periodic variability with an amplitude $\geq$ 0.005 mag. nor 
long term variations $\geq$ 0.01 mag. were seen.  
Percy et al. (2002) confirm that the Hipparcos observations of $\theta$ CrB 
show no evidence of short-term variability. Recently Percy \& Bakos (2001) 
reported that their observations of this star between 1996 and 1999 also
indicated constancy. In this bulletin, I report on additional photometric 
observations with the FCAPT which show that this behavior has continued for 
three more years.  These observations are inconsistent with those of Guerrero 
et al. (1992) which were obtained in 1989 when this star was in an active 
phase. 

During the 1999-2000, 2000-2001, and 2001-2002 observing 
seasons an additional 49, 42, and 11 high quality observations, respectively, 
were made.  Table 1 begins with the averages found by Adelman (1999) and 
summarizes the new observations, where c, ch and v are the comparison, the check and the variable star, respectively. The observing conditions, sequences and 
the comparison and check stars were the same as in Adelman (1999). The 
values for the last three seasons of observations are similar to those of the
previous FCAPT observations.  The new ensemble averages and standard deviations
are very similar to those from Adelman (1999). 

\vskip 1cm

Acknowledgements: This work was supported in part by NSF grant AST-0071260 and 
in part by grants from The Citadel Development Foundation.  I appreciate the 
continuing efforts of Louis J. Boyd, Robert J. Dukes, Jr., and George P. 
McCook to keep the FCAPT operating properly.


\newpage

{\small
\centerline{Table 1. Summary of photometry for $\theta$ CrB.}
\vskip 3mm
\begin{center}
\begin{tabular}{lrrrrrrrr}
\hline
Heliocentric &   $u$  &      & $v$   &      & $b$   &      & $y$   &     \\      
Julian Date  & $v-c$  & $c-ch$ & $v-c$ & $c-ch$ & $v-c$ & $c-ch$ & $v-c$ & $c-ch$ \\
\hline
           &        &       &        &       &       &       &       &     \\
all previous values &  &       &        &       &       &       &       &     \\
average    & $-$1.740 &$-$0.346 & $-$1.306 &$-$0.044 &$-$1.262 & 0.048 &$-$1.241 & 0.100\\
std. dev.  &  0.008 & 0.006 &  0.006 & 0.004 & 0.006 & 0.005 & 0.005 & 0.004\\
           &        &       &        &       &       &       &       &     \\
1999-2000  &        &       &        &       &       &       &       &     \\
49 observations  &  &       &        &       &       &       &       &     \\
average    &  $-$1.741& $-$0.344& $-$1.303 &$-$0.043 &$-$1.267 & 0.041 &$-$1.241 & 0.100\\
std. dev.  &   0.007&  0.005&  0.005 & 0.005 & 0.004 & 0.004 & 0.005 & 0.024\\
           &        &       &        &       &       &       &       &     \\
2000-2001  &        &       &        &       &       &       &       &     \\
42 observations  &  &       &        &       &       &       &       &     \\
average    &  $-$1.742& $-$0.344& $-$1.301 &$-$0.042 &$-$1.265 & 0.042 &$-$1.237 & 0.100\\
std. dev.  &   0.005&  0.005&  0.006 & 0.007 & 0.006 & 0.004 & 0.006 & 0.004\\
           &        &       &        &       &       &       &       &     \\
2001-2002  &        &       &        &       &       &       &       &     \\
11 observations  &  &       &        &       &       &       &       &     \\
average    &  $-$1.744& $-$0.352& $-$1.304 &$-$0.048 &$-$1.269 & 0.039 &$-$1.240 & 0.099\\
std. dev.  &   0.008&  0.003&  0.005 & 0.006 & 0.004 & 0.004 & 0.008 & 0.004\\
           &        &       &        &       &       &       &       &     \\
all FCAPT observations& &       &      &       &       &       &       &     \\
average    & $-$1.741 &$-$0.346 & $-$1.305 &$-$0.044 &$-$1.263 & 0.047 &$-$1.241 & 0.100\\
std. dev.  &  0.008 & 0.006 &  0.006 & 0.004 & 0.006 & 0.005 & 0.005 & 0.004\\
\hline
\end{tabular}
\end{center}
}

\references

Adelman, S. J., 1999, {\it IBVS}, 4729

ESA, 1997, {\it The Hipparcos and Tycho Catalogues}, SP-1200

Fabregat, J., Adelman, S. J., 1998, {\it A\&A}, {\bf 329}, 579

Guerrero, G., Bossi, M., Scardia, M., 1992, {\it A\&A}, {\bf 260}, 311

Percy, J. R., Attard, A., 1992, {\it PASP}, {\bf 104}, 1160

Percy, J. R., Bakos, A. G., 2001, {\it PASP}, {\bf 113}, 748 

Percy, J. R., Coffin, B. L., Drukier, G. A., et al., 1988, {\it PASP}, 
{\bf 100}, 1555

Percy, J. R., Hosick, J., Kincaide, H., Pang, C., 2002, {\it PASP}, {\bf 114},
551 

\endreferences

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