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\input ibvs2.sty

\begin{document}

\IBVShead{5276}{16 May 2002}

\IBVStitle{{\large ${\mathbf{BVRI}}$} observations of AH H\lowercase{er} in the years 2000-2001}
\IBVSauth{Spogli, Corrado$^1$; Fiorucci, Massimo$^1$; Tosti, Gino$^1$; Ciprini, Stefano$^1$; Nucciarelli, Giuliano$^1$; Macchia, Enrico$^2$; Monacelli, Giuseppe$^2$} 
\IBVSinst{Osservatorio Astronomico, Universit\`a di Perugia,
Via A. Pascoli I-06100 Perugia, Italy}
\IBVSinst{Associazione Astronomica Umbra, Via Ilci 7, Todi, Italy}


\SIMBADobj{AH Her}
\IBVStyp{ UGZ }
\IBVSkey{photometry}

\IBVSabs{In this paper we report BVRI observations of the dwarf nova}
\IBVSabs{AH Her during some outbursts.}


\begintext

AH Her is a dwarf nova, Z Cam subtype, that  varies in magnitude between 
$V$=14\fmm3 and $V$=11\fmm3 (for a review, see Spogli et al. 2001). 

In this paper we present the results of our observations made in the years 
2000-2001 at the Astronomical Observatory of the Perugia University in the
$B,\,V,\,R_C,\,I_C$ photometric  bands. The instruments used and the photometric 
techniques have been already described in Spogli et al. (1998). We used the 
calibration stars as reported in Spogli et al. (2001). 

The data are collected in two distinct tables relative to the 
above-mentioned years. The observations made in 2000 are few 
but significant: the object was discontinuously followed for 14 nights 
from 18/08/2000 to 27/09/2000 (see Table 2 and Figure 1). 
In 2001 the variable was instead well monitored: the data
collected goes from 15/07/2001 to 02/11/2001 for a total of 47 nights 
(see Table 3 and Figure 2). 
There is a gap in our observations in the month of September for the 
bad weather.    

Table 1 shows the main characteristics of the data and improves 
the values reported in Spogli et al. (2001). We computed the spectral slope 
for AH Her using the same procedure described in Spogli et al. (1998), 
confirming a values ranging from 0\fmm3 to 0\fmm7, with a mean value equal to 
0\fmm61$\pm$0\fmm08.
Figure 3 shows the colour-magnitude diagram for AH Her during the whole
outburst cycle: the data are well represented by a linear regression, in agreement with Spogli et al. (2001).

\vskip 5mm
\centerline{{\bf Table 1:} Photometric characteristics of AH Her during our observations.}
\vskip 3mm
\begin{center}
\begin{tabular}{lcccc}
\hline
                       &    $B$           &      $V$         &    $R_C$       &     $I_C$ \\
\hline
Maximum Outburst       & 11.57$\pm$0.09 & 11.58$\pm$0.04 & 11.52$\pm$0.05 & 11.41$\pm$0.03 \\
Minimum of Light       & 14.48$\pm$0.11   & 14.14$\pm$0.05 & 13.73$\pm$0.05 & 13.20$\pm$0.03 \\
Mean Values at Minimum & 14.0$\pm$0.3   & 13.7$\pm$0.3   & 13.3$\pm$0.2   & 12.9$\pm$0.2 \\
%                      &                &                &                &               \\
Outburst Amplitude     & 2.9            & 2.5            &  2.2           &  1.8      \\
Decay Rates(mag/day) &0.25$\pm$0.04 &0.22$\pm$0.04 &0.17$\pm$0.03& 0.14$\pm$0.03 \\
%                      &                &                &                & \\
 \hline
                       & ($B-V$)          &    ($V-R_C$)   &    ($V-I_C$)   & \\
 \hline
 Mean Values at Maximum& $-$0.02           &       0.06     &           0.21 & \\
 Mean Values at Minimum&  0.35           &       0.38     &           0.74 &
\\   \hline
\end{tabular}
\end {center}



\IBVSfig{8cm}{5276-f1.eps}{$V$ light curve of AH Her during August-September 2000. 
Circles represent the data here reported, while crosses are visual estimates available
from VSNET ({\tt http://vsnet.kusastro.kyoto-u.ac.jp/vsnet/})}


\IBVSfig{8cm}{5276-f2.eps}{$V$ light curve of AH Her during the summer-autumn 2001. 
Circles represent the data here reported, while crosses are visual estimates available
from VSNET.}

\IBVSfig{9cm}{5276-f3.eps}{Colour-magnitude diagram of AH Her during 2001. The dashed
line represent the linear regression.}



\begin{center}
\centerline{{\bf Table 2:} 2000 $BV(RI)_C$ data of AH Her}
\vskip 3mm
\begin{tabular}{cccccc}
\hline
Date  &JD       & $B$              & $V$           & $R_C$       & $I_C$ \\
&(2449000+) &                &               &             &    \\
\hline
  18/08/2000 &2775.387&12.01$\pm$0.13&11.96$\pm$0.04&11.87$\pm$0.05&11.77$\pm$0.06\\
  19/08/2000 &2776.319&12.11$\pm$0.12&12.09$\pm$0.04&12.02$\pm$0.05&      \\
  20/08/2000 &2777.344&12.19$\pm$0.12&12.33$\pm$0.03&12.17$\pm$0.05&12.05$\pm$0.04\\
  21/08/2000 &2778.314&12.66$\pm$0.14&12.31$\pm$0.09&12.40$\pm$0.07&      \\
  25/08/2000 &2782.311&13.61$\pm$0.12&13.45$\pm$0.04&13.17$\pm$0.06&12.69$\pm$0.04\\
  28/08/2000 &2785.308&14.39$\pm$0.17&13.89$\pm$0.05&13.30$\pm$0.05&12.88$\pm$0.03\\
  29/08/2000 &2786.306&14.01$\pm$0.12&13.68$\pm$0.04&13.33$\pm$0.04&12.95$\pm$0.04\\
  30/08/2000 &2787.305&14.28$\pm$0.14&14.14$\pm$0.05&     &13.25$\pm$0.09\\
  11/09/2000 &2799.292&11.74$\pm$0.13&11.76$\pm$0.04&11.68$\pm$0.04&11.57$\pm$0.04\\
  12/09/2000 &2800.291&11.89$\pm$0.16&11.95$\pm$0.04&11.79$\pm$0.05&11.69$\pm$0.04\\
  15/09/2000 &2803.288&12.44$\pm$0.08&12.37$\pm$0.05&12.31$\pm$0.05&12.06$\pm$0.04\\
  22/09/2000 &2810.278&14.48$\pm$0.11&14.13$\pm$0.04&13.73$\pm$0.06&13.20$\pm$0.03\\
  25/09/2000 &2813.286&13.01$\pm$0.08&13.01$\pm$0.04&      &       \\
  27/09/2000 &2815.272&12.37$\pm$0.11&12.31$\pm$0.04&12.20$\pm$0.05&12.06$\pm$0.03\\
  
\hline
\end{tabular}
\end {center}
\vskip 0.5cm

\references

Spogli C., Fiorucci M., Tosti G., 1998, {\it A\&AS}, {\bf 130}, 485 
%%\BIBCODE{1998A&AS..130..485S}

Spogli C., Fiorucci M., Tosti G., Raimondo G, 2001, {\it IBVS}, {\bf 5147}
%%\BIBCODE{2001IBVS.5147....1S}

\endreferences


\vspace*{-1cm}

\begin{center}
\centerline{{\bf Table 3:} 2001 $BV(RI)_C$ data of AH Her}
\vspace*{-0.25cm}
\begin{tabular}{cccccc}
\hline
 Date &JD       & $B$              & $V$           & $R_C$       & $I_C$ \\
&(2449000+) &                &               &             &    \\
\hline
  15/07/2001 &3106.375&12.26$\pm$0.05&12.35$\pm$0.03&12.23$\pm$0.05&12.01$\pm$0.04\\
  17/07/2001 &3104.392&11.57$\pm$0.08&11.58$\pm$0.04&11.52$\pm$0.05&              \\
  18/07/2001 &3109.368&11.61$\pm$0.09&11.63$\pm$0.03&11.54$\pm$0.04&11.41$\pm$0.03\\
  19/07/2001 &3110.391&11.73$\pm$0.11&11.71$\pm$0.04&11.70$\pm$0.05&11.54$\pm$0.05\\
  22/07/2001 &3113.355&11.94$\pm$0.11&12.16$\pm$0.03&11.89$\pm$0.05&11.76$\pm$0.04\\
  23/07/2001 &3114.365&12.09$\pm$0.08&13.84$\pm$0.05&12.05$\pm$0.04&11.91$\pm$0.05\\
  24/07/2001 &3115.354&12.55$\pm$0.07&12.46$\pm$0.05&12.35$\pm$0.05&12.13$\pm$0.04\\
  26/07/2001 &3117.352&13.35$\pm$0.08&13.34$\pm$0.04&13.04$\pm$0.04&12.72$\pm$0.04\\
  03/08/2001 &3125.396&13.76$\pm$0.11&13.54$\pm$0.08&13.20$\pm$0.05&12.84$\pm$0.03\\
  04/08/2001 &3126.333&13.40$\pm$0.07&13.26$\pm$0.05&13.01$\pm$0.04&12.69$\pm$0.04\\
  05/08/2001 &3127.334&13.98$\pm$0.13&              &              &              \\
  06/08/2001 &3128.336&12.51$\pm$0.07&12.48$\pm$0.03&12.35$\pm$0.05&12.19$\pm$0.03\\
  07/08/2001 &3129.332&12.25$\pm$0.11&11.97$\pm$0.04&11.91$\pm$0.05&11.82$\pm$0.05\\
  09/08/2001 &3131.329&12.03$\pm$0.12&11.82$\pm$0.04&11.88$\pm$0.05&11.66$\pm$0.06\\
  10/08/2001 &3132.327&11.97$\pm$0.11&11.92$\pm$0.04&11.81$\pm$0.05&              \\
  11/08/2001 &3133.327&11.72$\pm$0.13&11.82$\pm$0.03&11.71$\pm$0.05&11.65$\pm$0.04\\
  12/08/2001 &3134.326&11.96$\pm$0.11&11.95$\pm$0.04&11.86$\pm$0.05&11.67$\pm$0.04\\
  13/08/2001 &3135.327&12.39$\pm$0.09&12.14$\pm$0.04&12.05$\pm$0.05&              \\
  14/08/2001 &3136.323&12.41$\pm$0.11&12.33$\pm$0.04&12.23$\pm$0.05& \\
  15/08/2001 &3137.325&12.81$\pm$0.12&12.73$\pm$0.04&12.59$\pm$0.05&12.31$\pm$0.06 \\
  18/08/2001 &3140.318&13.73$\pm$0.08&13.53$\pm$0.04&13.19$\pm$0.05&              \\
  19/08/2001 &3141.323&13.94$\pm$0.09&13.52$\pm$0.04&              &              \\
  20/08/2001 &3142.337&13.89$\pm$0.09&13.70$\pm$0.05&              &              \\
  21/08/2001 &3143.358&14.36$\pm$0.11&13.95$\pm$0.03&13.49$\pm$0.06&13.06$\pm$0.04\\
  26/08/2001 &3148.302&12.26$\pm$0.16&                         &              &   \\ 
  27/08/2001 &3149.369&11.91$\pm$0.08&11.84$\pm$0.04&11.87$\pm$0.05&11.77$\pm$0.04\\
  28/08/2001 &3150.308&11.81$\pm$0.09&11.89$\pm$0.04&11.82$\pm$0.05&11.69$\pm$0.04\\
  29/08/2001 &3151.337&11.89$\pm$0.07&11.90$\pm$0.04&12.03$\pm$0.05&11.66$\pm$0.04\\
  03/09/2001 &3156.301&12.13$\pm$0.13&12.14$\pm$0.04&11.95$\pm$0.05&11.85$\pm$0.03\\
  05/09/2001 &3158.356&12.91$\pm$0.11&12.79$\pm$0.04&12.63$\pm$0.05&12.33$\pm$0.03\\
  07/09/2001 &3160.295&13.81$\pm$0.10&13.49$\pm$0.05&13.22$\pm$0.06&12.84$\pm$0.03\\
  12/09/2001 &3165.291&13.57$\pm$0.11&12.99$\pm$0.04&12.94$\pm$0.05&12.48$\pm$0.03\\
  07/10/2001 &3190.279&12.41$\pm$0.06&12.48$\pm$0.05&12.28$\pm$0.05&12.12$\pm$0.04\\ 
  09/10/2001 &3192.276&13.20$\pm$0.05&13.11$\pm$0.04&12.85$\pm$0.05&12.59$\pm$0.03\\
  11/10/2001 &3194.254&14.10$\pm$0.08&13.83$\pm$0.04&13.44$\pm$0.05&              \\
  12/10/2001 &3195.253&13.78$\pm$0.06&13.72$\pm$0.04&13.39$\pm$0.05&12.93$\pm$0.03\\
  13/10/2001 &3196.287&14.04$\pm$0.08&13.74$\pm$0.04&13.31$\pm$0.05&12.87$\pm$0.03\\
  14/10/2001 &3197.251&14.18$\pm$0.12&13.76$\pm$0.04&13.36$\pm$0.05&12.86$\pm$0.04\\
  16/10/2001 &3199.275&              &13.61$\pm$0.05&13.18$\pm$0.05&12.83$\pm$0.04\\
  17/10/2001 &3200.251&13.88$\pm$0.16&13.03$\pm$0.05&13.05$\pm$0.05&12.61$\pm$0.05\\
  18/10/2001 &3201.275&13.29$\pm$0.16&13.09$\pm$0.05&12.84$\pm$0.05&12.53$\pm$0.04\\ 
  19/10/2001 &3202.249&11.96$\pm$0.09&11.91$\pm$0.04&11.88$\pm$0.05&11.77$\pm$0.05\\
  22/10/2001 &3205.246&12.42$\pm$0.11&12.25$\pm$0.04&12.17$\pm$0.07&11.96$\pm$0.05\\
  25/10/2001 &3208.243&13.59$\pm$0.06&13.47$\pm$0.05&13.15$\pm$0.05&12.73$\pm$0.04\\
  27/10/2001 &3210.241&14.47$\pm$0.06&13.90$\pm$0.04&13.48$\pm$0.05&13.10$\pm$0.05\\
  29/10/2001 &3212.239&14.06$\pm$0.12&              &              &12.68$\pm$0.05\\
  02/11/2001 &3216.234&13.98$\pm$0.08&13.82$\pm$0.04&13.36$\pm$0.05&              \\   
\hline
\end{tabular}
\end {center}



\end{document}

