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\IBVShead{4894}{26 April 2000}
\IBVStitle{Photometry of stars in the field of CQ Tauri}
\IBVSauth{Skiff, Brian A.}
\IBVSinsto{Lowell Observatory, 1400 West Mars Hill Road, Flagstaff\enskip AZ\enskip 86001-4499, USA\enskip (bas@lowell.edu)} %email


\begintext

CQ Tauri (HD\,36910) is a variable pre-main-sequence star ranging mostly
between visual magnitudes 9\mm\,and 11\fmm5.  The AAVSO `standard' (d)-scale
chart for this star (AAVSO 2000) shows magnitudes from the survey by Kalandadze
(1964), who provided photographic $UBV$ photometry and MK spectral types for some
3600 stars in the Taurus/Gemini Milky Way.  As a check on the magnitude
zero-point and scale, I have done $V/(b-y)$ photometry of many of the
sequence stars in the field.  The results were originally distributed via the
`vsnet' list-server (Skiff 1995).

I observed the stars on the UT dates 31 October and 30 November 1994
using the Lowell 53-cm photometric telescope, 29\arcs\,aperture, and Str\"omgren
$y$ and $b$ filters.  A total of 23 and 30 primary and secondary standards were
observed on the respective nights whose residuals averaged 0\fmm007 in both
$V$ and $b-y$.  Mean extinction coefficients (Lockwood \& Thompson 1986)
were applied in the reductions.

Table 1 shows the results for the stars in order of decreasing brightness.
Observations of CQ Tauri on the two nights are shown in the first entry.  An
asterisk by the star name indicates a note following the table.  The positions
are from Tycho-2 (H{\o}g {\it et al}.\ 2000).  Most of the stars were observed
on both nights, and the {\it rms}\, dispersion of these are given in the second
line of the relevant entries.

The $V$ magnitudes of Kalandadze, although internally consistent, show
a zero-point error of about $-0\fmm2$ (Kalandadze too bright).  The MK
types shown in the table are mostly from this source as well.  These
appear to be quite reliable, and show the effects of reddening by the
Taurus dark clouds in the middle distance.  A later survey of the same
region by Chargeishvili (1988) gives similar types for the same stars.
Visual observations of CQ Tauri in the AAVSO database ({\tt
http://www.aavso.org/aavso/curvegenerator.shtml}) are consistent with
my $V$ magnitudes made on the same dates despite the offset in the chart
zero-point, which perhaps compensates roughly for the color term
between $V$ and the dark-adapted visual response.  The two measurements
of the carbon star HD\,244898 suggest it is a small-amplitude
variable.  The observations by Paupers {\it et al}.\ (1994) show it
about 0\fmm3 brighter, so variability seems certain.  The star is not
especially red. 

\newpage

\begin{center}
\normalsize
{Table 1:  Photometry of stars in the field of CQ Tauri \phantom {(}} \\
\vskip 1mm
\begin{tabular}{lllrrcll}
\hline
Name & \multicolumn{2}{c}{RA\quad (2000)\quad Dec}& \multicolumn{1}{c}{$V$} & \multicolumn{1}{c}{$b-y$} & $n$ & spec & Remarks \\
\hline
CQ Tauri*     & 5\hr35\mm58\fsec46 & +24\deg44\arcm54\farcs1 & 11.040 & 0.517 & & F2IVe  & HD 36910  \\
              &            &             & 10.413 & 0.534 & &        &   \\
HD 36758      & 5 35 03.57 & +24 17 26.8 &  6.829 & 0.653 &2& G8     & IRAS 05320+2415  \\
              &            &             &   .002 &  .000 & &        &   \\
HD 37012      & 5 36 28.06 & +24 22 06.4 &  8.003 & 1.267 &2& K5II   &   \\
              &            &             &   .004 &  .001 & &        &   \\
HD 245084*    & 5 35 23.67 & +25 01 20.3 &  8.563 & 0.773 &2& G8III  &   \\
              &            &             &   .004 &  .006 & &        &   \\
HD 245225     & 5 36 07.87 & +24 28 42.3 &  9.129 & 1.042 &2& K3III  &   \\
              &            &             &   .001 &  .008 & &        &   \\
HD 245133     & 5 35 33.62 & +24 31 56.2 &  9.268 & 0.301 &2& B9V    &   \\
              &            &             &   .003 &  .004 & &        &   \\
HD 244897     & 5 34 23.70 & +24 55 21.8 &  9.670 & 0.983 &2& K0     & GSC 1852-0119  \\
              &            &             &   .003 &  .011 & &        &   \\
HD 245180*    & 5 35 49.70 & +24 55 22.8 &  9.812 & 0.227 &2& B3V    &   \\
              &            &             &   .001 &  .009 & &        &   \\
HD 244898*    & 5 34 25.47 & +24 51 11.8 & 10.065 & 1.020 & & C4,4   & CGCS 990  \\
              &            &             & 10.112 & 1.012 & &        &   \\
HD 245030*    & 5 35 02.87 & +24 29 04.9 & 10.132 & 0.357 &1& G2IV   &   \\
HD 245224     & 5 36 04.13 & +24 31 23.1 & 10.298 & 0.375 &2& A5     &   \\
              &            &             &   .004 &  .015 & &        &   \\
HD 245029*    & 5 35 05.05 & +24 37 05.4 & 10.501 & 0.560 &1& F5     &   \\
BD+24\deg879  & 5 36 25.04 & +24 47 52.2 & 10.893 & 0.355 &2& B3IIIe & LS V +24\deg3  \\
              &            &             &   .004 &  .001 & &        &   \\
GSC 1865-1630*& 5 35 56.11 & +24 42 47.6 & 11.457 & 0.438 &2& G5:    &   \\
              &            &             &   .003 &  .004 & &        &   \\
GSC 1865-1722 & 5 36 35.96 & +24 44 03.7 & 11.878 & 0.440 &1& A1     &   \\
\hline
\end{tabular}

\begin{tabular}{ll}
Notes \\
CQ Tauri       & observations on 31 Oct 1994 UT (JD 2449656.9) and \\
               & 30 Nov 1994 UT (JD 2449686.9).  \\
HD 245084      & $V = 8.55$ (Yoss {\it et al}.\ 1991).  \\
HD 245180      & close double; $V = 9.814$, $b-y = 0.223$ (Westin 1982).  \\
HD 244898      & observations on 31 Oct 1994 UT (JD 2449656.9) and \\
               & 30 Nov 1994 UT (JD 2449686.9).  $V = 9.73$ (Paupers {\it et al}.\ 1994).  \\
HD 245030      & $V = 10.12$ (Yoss {\it et al}.\ 1991).  \\
HD 245029      & BD+24\deg867 = GSC 1865-1744.  \\
GSC 1865-1630  & probably a dwarf on the basis of $b-y$ color and modest proper motion.  \\
\end{tabular}
\end{center}

\references

AAVSO, 2000, {\tt http://charts.aavso.org/STANDARD/TAU/CQ\_TAU}

Chargeishvili, K. B., 1988, {\it Byull.\ Abastumanskaya Astrofiz.\ Obs.}, {\bf 65}, 3   %\BIBCODE {1988AbaOB..65....3C}

H{\o}g, E., Fabricius, C., Makarov, V. V., Urban, S. E., Corbin, T.,
Wycoff, G., Bastian, U., Schwekendiek, P., and Wicenec, A., 2000, {\it Astron.\ 
Astrophys.}, {\bf 355}, L27   

Kalandadze, N. B., 1964, {\it Byull.\ Abastumanskaya Astrofiz.\ Obs.}, {\bf 31}, 66  % \BIBCODE {1964AbaOB..31...66K}

Lockwood, G. W., and Thompson, D. T., 1986, {\it Astron.\ J.}, {\bf 92}, 976   

Paupers O., Zaime D., and Eglitis I., 1994, {\it Baltic Astron.}, {\bf 2}, 268  % \BIBCODE {1994BaltA...2..268P}

Skiff, B. A., 1995,  \\
{\tt http://www.kusastro.kyoto-u.ac.jp/vsnet/Mail/vsnet/msg00092.html}

Westin, T. N. G., 1982, {\it Astron.\ Astrophys.,  Suppl.\ Ser.}, {\bf 49}, 561  

Yoss, K., Bell, D. J., and Detweiler, H. L., 1991, {\it Astron.\ J.}, {\bf 102}, 975  

\endreferences

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