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\IBVShead{5072}{11 May 2001}

\IBVStitle{BVR Photometry of SN2000E}

\IBVSauth{Devyatkin, A.V.; Gorshanov, D.L.} 

\IBVSinsto{Main Astronomical Observatory of RAS (Pulkovo), Saint-Petersburg,
Russia; e-mail: densvet@mail.ru } 

\SIMBADobj{SN 2000E}
\IBVSkey{photometry}

\begintext

The supernova SN2000E was discovered by Valentini et al.\ (2000) on
January 26.73 in the NGC 6951 galaxy.  From February 1 to May 15, 2000
we have observed the supernova SN2000E at Pulkovo Observatory with a
ZA-320 32-cm reflector (Bekiashev et al.\ 1998) equipped with SBIG ST-6
CCD camera.  The observations were made in the $B$, $V$ and $R$ bands
of Johnson's photometric system.

Stellar images on the frames were measured by aperture photometry
technique using ``Apex'' code developed at Pulkovo Observatory
(Devyatkin et al.\ 2000).

The field of view of the instrument with ST-6 camera is $9\farcm5
\times 7\farcm5$.  Hence no standard stars were found in the same frame
with the supernova. During several nights we observed four standard
stars (HD 194258, HD 196229, HD 196848, HD 197894) taken from ``The
catalogue of $WBVR$ magnitudes of bright stars of Northern sky'' (Kornilov
et al.\ 1991).  An additional star G262-16 (Carney \& Latham, 1987) was also
observed (in $B$ and $V$ only). These stars are located within 1 to 4
degrees from the supernova.  Using these five stars we found rough
magnitudes for 20--30 field stars located in the same frame as the
supernova. This procedure was made by a method similar to usual
differential photoelectric photometry.  The brightness of the supernova
was referred to this group of field stars for all dates of
observations.

The results are listed in Table~1 and drawn in Figure~1. We
estimate the final accuracy of the results 0\fmm12 for $B$,
0\fmm08 for $V$ and 0\fmm06 for $R$ from February to March (JD
2451576--2451634). In April and May (after JD 2451640) the
brightness of the supernova decreased and the brightness of the
sky background increased (because the latitude of Pulkovo
Observatory is +60\deg). Hence accuracy of the
observations became worse: 0\fmm25 for $B$, 0\fmm20 for $V$ and
0\fmm13 for $R$.

Our observations started 6 days after the discovery of the supernova. 
The first three measurements (made during 5 days) were significantly 
brighter than the discovery brightness of the supernova in $B$ and $V$ 
(Valentini et al.\ 2000). Very probably, our observations started at 
the maximum light of the supernova. After this time the supernova started 
fading with a rate of approximately 0.06, 0.05 and 0.04 magnitudes/day 
in $B$, $V$ and $R$, respectively. 

\IBVSfig{21cm}{5072-f1.ps}{Observations of SN 2000E in $B$, $V$ and $R$
colours. The open circles show the discovery brightness of the supernova
from Valentini et al.\ (2000), with their error bars. For comparison, we
also plot the errors of the first data of the two parts of our
observations with different accuracies, see text}

\newpage
\begin{center}
{\normalsize Table 1}
\vskip 2mm
\begin{tabular}{cccc}
\hline
JD          & $B$   & $V$   & $R_J$   \\
\hline
2451576.198 & 14.53 & 13.91 & 13.64 \\
2451578.332 & 14.58 & 13.81 & 13.60 \\
2451580.225 & 14.53 & 13.81 & 13.61 \\
2451585.199 & 14.59 & 14.01 & 13.76 \\
2451590.240 & 15.18 & 14.18 & 13.94 \\
2451595.227 & 15.53 & 14.48 & 13.93 \\
2451596.378 & 15.84 & 14.66 & 14.09 \\
2451598.353 &       & 14.70 & 14.15 \\
2451599.511 & 15.73 & 14.60 & 14.12 \\
2451600.396 & 15.77 & 14.83 & 14.18 \\
2451601.505 & 16.05 & 14.71 & 14.11 \\
2451612.554 & 16.67 & 15.30 & 14.52 \\
2451616.319 & 16.92 & 15.72 &       \\
2451618.260 & 16.73 & 15.42 &       \\
2451622.449 & 17.17 & 15.87 & 14.88 \\
2451623.276 &       &       & 15.05 \\
2451625.334 &       & 15.80 &       \\
2451626.373 & 16.73 & 15.82 & 15.19 \\
2451628.481 &       &       & 15.13 \\
2451630.386 & 16.92 & 15.92 & 15.17 \\
2451631.411 & 16.92 & 15.75 &       \\
2451634.358 & 17.00 & 15.92 & 15.11 \\
2451641.398 & 17.36 & 16.14 &       \\
2451644.362 &       & 16.53 & 15.64 \\
2451650.446 & 16.94 & 16.25 & 15.60 \\
2451653.395 & 16.86 & 17.16 & 15.44 \\
2451654.370 & 16.86 & 17.11 &       \\
2451655.376 &       & 18.56 & 15.28 \\
2451656.413 &       & 17.02 & 16.14 \\
2451658.379 &       &       & 15.54 \\
2451659.374 &       &       & 16.18 \\
2451665.421 & 16.95 & 16.21 & 15.66 \\
2451666.443 & 17.21 & 16.31 & 15.97 \\
2451667.446 &       & 16.37 & 16.14 \\
2451669.483 &       &       & 15.71 \\
2451671.440 & 17.48 & 16.29 & 15.97 \\
2451672.487 &       & 16.09 &       \\
2451673.465 &       &       & 15.74 \\
2451674.425 & 17.30 & 16.59 & 15.79 \\
2451677.423 & 17.13 & 16.15 & 15.52 \\
2451680.440 &       &       & 16.51 \\
\hline
\end{tabular}
\end{center}
\newpage

{\it Acknowledgments.} The authors thank Pulkovo Observatory
researchers A.~Gritsuk, E.~Kornilov, V.~Kouprianov and A.~Salovatova
for collaboration in the observations as well as I.~Kanaev and
N.~Sokolov for useful discussion.


\references

Bekiashev, R.H., Kanaev, I.I., et al., 1998, {\it Izvestiya GAO}, No.\ 213,
249 (in Russian)

Carney, B.W., Latham, D.W., 1987, {\it AJ}, {\bf 93}, 116

Devyatkin, A.V., Gritsuk, A.N., Gorshanov, D.L., Kornilov, E.V., 2000,
{\it Izvestiya GAO}, No.\ 214, 455 (in Russian)

Kornilov, V.G., Volkov, I.M., et al., 1991, Trudy GAIS, Moscow Univ.\
(in Russian)

Valentini, G., et al., 2000, {\it IAU Circ.}, No.\ 7351

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