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\input ibvs2.sty
\input ibvst.sty

\begin{document}

\IBVShead{4973}{26 October 2000}

\IBVStitle{NSV 01756: a Red Variable in Eridanus}

\IBVSauth{Gomez-Forrellad, Josep M.$^1$; Henden, Arne A.$^2$}

\IBVSinst{Grup d'Estudis Astronomics, Apartado 9481, 08080 Barcelona,
Spain, e-mail: jmgomez@astrogea.org}

\IBVSinst{USRA/USNO, P.O. Box 1149, Flagstaff, AZ 86002-1149, USA,
e-mail: aah@nofs.navy.mil}

\SIMBADobj{NSV 01756}

\begintext

\IBVSTnam{BD\,$-$05\deg1073 = GSC 4745\_1397 = HV 10413 = CSV 000454}

\IBVSTcoo{04\hr 53\mm 27\fsec83}{$-$05\deg 34\arcm 49\farcs0}{2000.0}

\IBVSTobs{Mollet del Valles Observatory, 0.4-m Newton telescope\\
US Naval Observatory Flagstaff Station, 1.0-m Ritchey--Chretien telescope}

\IBVSTdet{CCD in all cases}

\IBVSfig{8cm}{4973-f1.eps}{Field of NSV 01756 (V = variable) made from
RealSky (1996), and the standardized field stars listed in Table~1}

\IBVSfig{9cm}{4973-f2.eps}

\begin{center}
{\normalsize Table 1}
\vskip2mm
\begin{tabular}{cccccccccc}
\hline
Star & GSC & $V$ & s.d. & $B-V$ & s.d. & $V-R_c$ & s.d. & $R_c-I_c$ & s.d. \\
\hline
A & 4745\_1330 & 11.063 & 0.013 & 0.502 & 0.017 & 0.299 & 0.013 & 0.309 & 0.009 \\
B & 4745\_1403 & 10.599 & 0.008 & 0.536 & 0.018 & 0.311 & 0.013 & 0.311 & 0.008 \\
C & 4749\_0698 & 11.609 & 0.008 & 0.538 & 0.012 & 0.335 & 0.011 & 0.287 & 0.010 \\
D & 4745\_1325 & 10.376 & 0.016 & 1.154 & 0.017 & 0.592 & 0.024 & 0.512 & 0.011 \\
E & 4745\_1227 & 13.759 & 0.027 & 0.586 & 0.053 & 0.370 & 0.036 & 0.341 & 0.107 \\
F & 4745\_1303 & 13.036 & 0.014 & 1.384 & 0.056 & 0.733 & 0.016 & 0.669 & 0.035 \\
G & 4745\_1360 & 13.399 & 0.031 & 0.791 & 0.055 & 0.419 & 0.042 & 0.480 & 0.056 \\
H & 4749\_0397 & 13.216 & 0.006 & 0.527 & 0.033 & 0.336 & 0.029 & 0.299 & 0.060 \\
\hline
\end{tabular}

\bigskip

{\normalsize Table 2}
\vskip2mm
\begin{tabular}{lcccccccc}
\hline
JD 2400000\,+ & $V$ & s.d. & $B-V$ & s.d. & $V-R_c$ & s.d. & $R_c-I_c$ & s.d. \\
\hline
50516.6661 & 10.755 & 0.001 & 1.671 & 0.001 & 1.317 & 0.003 & 1.738 & 0.001 \\
50517.6592 & 10.755 & 0.002 & 1.655 & 0.002 & 1.323 & 0.005 & 1.730 & 0.001 \\
50518.6260 & 10.793 & 0.003 & 1.642 & 0.004 & 1.325 & 0.002 & 1.766 & 0.002 \\
50521.6297 & 10.819 & 0.002 & 1.647 & 0.004 & 1.321 & 0.003 & 1.756 & 0.003 \\
50753.8732 & 10.839 & 0.001 & 1.668 & 0.002 & 1.336 & 0.001 & 1.754 & 0.001 \\
50776.9077 & 10.714 & 0.002 & 1.651 & 0.003 & 1.335 & 0.003 &  ---  &  ---  \\
50821.7318 & 10.866 & 0.001 & 1.598 & 0.003 & 1.344 & 0.003 & 1.856 & 0.002 \\
50835.7631 & 10.703 & 0.003 & 1.590 & 0.005 & 1.312 & 0.002 & 1.829 & 0.002 \\
50836.6767 & 10.677 & 0.002 & 1.617 & 0.004 & 1.303 & 0.003 & 1.823 & 0.004 \\
50837.6255 & 10.660 & 0.002 & 1.615 & 0.002 & 1.293 & 0.002 & 1.802 & 0.003 \\
50838.7089 & 10.644 & 0.002 & 1.626 & 0.002 & 1.288 & 0.003 & 1.767 & 0.004 \\
50839.6702 & 10.643 & 0.001 & 1.622 & 0.001 & 1.289 & 0.002 & 1.802 & 0.005 \\
\hline
\end{tabular}
\end{center}

\newpage

\IBVSTfil{$B,V,R,I$}

\IBVSTcomp{BD\,$-$05\deg1072 = PPM 701872 = GSC 4745\_1325}

\IBVSTchk{GSC 4745\_1330}

\IBVSTsys{Johnson--Cousins}{Landolt standards (Landolt, 1992)}

\IBVSTdata{Tables 1 and 2}

\IBVSTtyp{ SR }

\IBVSTrem{
The variability of NSV 01756 was announced by Handley and Shapley
(1940).  They indicated that this object was an eclipsing binary star
with a photographic magnitude variation from 12\fmm8 to 13\fmm5.
Bidelman (1987) estimated an M4 spectral type. To know more about NSV
01756, the star was systematically observed in the $V$ band for 61
nights from October 1996 to March 1997, and occasionally observed in
1995 and 1998. Some observations were obtained in $B$, $R$ and $I$
bands.  Figure~1 shows the field of NSV 01756.  Table~1 lists the
standardized $V$ magnitudes and color indices of comparison stars near
the variable, while Table~2 lists the color indices for NSV 01756.
Observations show no evidence for the star to be an eclipsing binary.
The light curve suggests that probably it is a semiregular variable.
The maximum detected amplitude in the $V$ band was 0\fmm84, from
10\fmm25 to 11\fmm10 (Figure~2). Data show two successive light maxima
separated by a time span of 100 days, but since SR stars show period
variations between successive light maxima, more observations should be
performed to ascertain the long term behavior of NSV 01756.}

\references

Bidelman, W.P., 1987, {\it IBVS}, No.\ 2993

Handley, C.M., Shapley, H., 1940, {\it HB}, No.\ 913

Landolt, A.U., 1992, {\it AJ}, {\bf 104}, 340

RealSky, 1996, The Astronomical Society of the Pacific and the Space
Telescope Science Institute, San Francisco

\end{document}
