\documentstyle[twoside,epsfig]{article}

\input{ibvs2.sty}

\begin{document}

\IBVShead{5264}{20 April 2002}

\IBVStitle{UBVRI Photometry of SN 2002\lowercase{ap} in M74}

\IBVSauth{Borisov,  G.$^1$; Dimitrov, D.$^1$; Semkov, E.$^1$; Apostolovska, G.$^2$; Bonev, T.$^1$; \break Ivanova, A.$^1$; Bilkina, B.$^1$; Ivanova, V.$^1$; Panov, K.$^1$ }

\IBVSinst{Institute of Astronomy, Bulgarian Academy of Sciences, Tzarigradsko Chosse 72, 1784 Sofia, Bulgaria }
\IBVSinst{Institute of Physics, Faculty of Natural Sciences, P.O. Box 162, 91000 Skopje, Macedonia}

\SIMBADobj{SN 2002ap}

\NEDobj{M74}
\NEDobj{SN 2002ap}

\begintext

The Supernova SN 2002ap in M74 was discovered by Y. Hirose (reported by Nakano
et al., 2002) on Jan. 29, 2002. Low resolution spectra by Kinugasa et
al. (2002), Meikle et al. (2002), and Filippenko and Chornock (2002) showed
that  overall spectral features resemble that of the Ic SN -- type, called
also ``hypernovae'' (see Filippenko, 1997). Detailed studies revealed that
progenitor mass of SN 2002ap, as well as explosion energy and ejected mass are
smaller than the respective values for a typical ``hypernovae'' (Mazzali et
al., 2002). The radial velocity of SN 2002ap matches well the red - shift of
M74 (Smartt and Meikle, 2002), which confirms the association of SN 2002ap
with the M74 host galaxy. 

In this note we report $UBVRI$ photometry of SN 2002ap, obtained at Rozhen
National Astronomical Observatory, Bulgaria, and using all our 3 optical
telescopes: 2-m Ritchey -- Chretien telescope with Photometrics CCD camera
(1024$\times$1024), 60-cm Cassegrain with photon counting, UBV photometer, and
the 50/70-cm Schmidt telescope with SBIG ST8 CCD. The observations were
carried out during February and March, 2002. Standard reduction procedure was
applied to the differential photometry of SN 2002ap with respect to the
comparison star No~1 = GSC~1205~789 (see Gal--Yam et al., 2002), where the
$UBVRI$ mags are from Henden (2002). We estimate that our errors are not
larger than 0.06 mag.

The Rozhen observations are listed in Table~1.

For the light curves, we added other observations, as follows : 7U, 12B,
326V, 13R, 15I - data by Gal--Yam et al. (2002); 2I data by Mattila and Meikle
(2002); 3R data by Hornoch (2002); 2U, 2B, 2V and 2R data by Yoshii et
al. (2002); 5U, 5B, 5R data by Riffeser et al. (2002). We find good agreement
of all data sets and the combined light curves of SN 2002ap are shown on
Figure~1. From Figure~1,  we estimate that maximum brightness in V occurred
on Feb 8.7 UT. However, there is a shift of the maximum light in the different
passbands, with a progressive delay of maximum at longer wavelengths. This has
also been noticed by Gal--Yam et al. (2002). In Table~2, we show for
respective passbands the JD and the magnitude at maximum, as well as the slopes
of the light curves after maximum. Figure~2 shows the color curves. In
Figure~2, reddening in all colours is apparent, which is caused by the delay
of maximum and by the different slopes after the maximum in the different
passbands. The total light amplitude of SN 2002ap remains unknown, as
prediscovery images (Vreeswijk and Smartt, 2002) show no visible star at that
position to the limiting magnitude. For the maximum light, with $V$ =
12\fmm38, $E(B - V)$ = 0\fmm09 (Takada -- Hidaii et al., 2002, see in Mazzali
et al., 2002), standard reddening law and distance to M74 of 8 Mpc (Sharina et al., 1996), we get for the SN 2002ap : Mv = $-$17.4. 

\vspace*{-1cm}

\begin{center}
\vskip 10mm
\centerline{Table 1: UBVRI Photometry of SN 2002ap from Rozhen NAO.}
\vskip 5mm
\begin{tabular}{|c|c|c|c|c|c|c|}
\hline
         JD           &       $U$       &       $B$       &        $V$       &        $R$      &        $I$        & Telescope \\
\hline
2452310.213  &  13.326   &  13.138   &   12.501   &  12.582   &  12.590   &  2-m RCC   \\
2452311.280  &  13.309   &  13.082   &   12.442   &  12.447   &  12.442   &  2-m RCC   \\
2452312.242  &  13.499   &  13.150   &   12.427   &  12.413   &  12.423   &  2-m RCC   \\
2452313.256  &  13.608   &  13.152   &   12.380   &  12.327   &  12.327   &  2-m RCC   \\
2452315.259  &       $-$       &  13.245   &   12.292   &        $-$      &        $-$       &  60-cm         \\ 
2452315.214  &       $-$       &  13.341   &   12.376   &  12.273   &  11.979   &  Schmidt    \\
2452319.249  &       $-$       &  13.717   &   12.591   &  12.326   &  12.214   &  Schmidt    \\   
2452340.221  &       $-$       &       $-$       &   14.149   &  13.702   &  13.138   &  2-m RCC    \\   
2452352.235  &       $-$       &       $-$       &   14.500   &  14.012   &  13.353   &  Schmidt    \\    
\hline 
\end{tabular}
\vskip 10mm
\centerline{Table 2: SN 2002ap :  JD, magnitudes at maximum and slopes after maximum.}
\vskip 5mm
\begin{tabular}{|c|c|c|c|c|c|}
\hline
                  &     $U$      &     $B$     &      $V$     &      $R$     &      $I$       \\
\hline
JD$-$2452000    &  309.2  &  310.8  &  314.2  &  314.9  &  317.5  \\
Magnitude &  13.23  &  13.19  &  12.38  &  12.24  &  12.18  \\
Slope  [mag/day] &   0.12   &   0.08   &   0.07   &   0.06   &   0.04  \\ 
\hline
\end{tabular}
\end{center}

\vspace*{-0.5cm}

\IBVSfig{9cm}{5264-f1.eps}{$UBVRI$ light curves of SN 2002ap. Encircled symbols are observations from NAO Rozhen. Light curves in $U$, $R$ and $I$ are shifted in ordinate for better presentation.}


\newpage
\IBVSfig{9cm}{5264-f2.eps}{Colour curves of SN 2002ap. Encircled symbols are observations from NAO Rozhen.}


\references

Filippenko, A.V., 1997, {\it ARA\&A}, {\bf 35}, 309

Filippenko, A.V., Chornock, R., 2002, {\it IAUCirc}, {\bf 7825}

Gal--Yam, A., Ofek, E., Shemmer, O., 2002, {\it MNRAS}, submitted

Henden, A., 2002, {\it GCN}, {\bf 1242}

Hornoch, K., 2002, {\it IAUCirc.}, {\bf 7820}

Kinugasa, K., Kawakita, H., Ayani, K., Kawabata, T., Yamaoka, H., 2002, {\it IAUCirc}, {\bf 7811}

Mattila, S., Meikle, P., 2002, {\it IAUCirc}, {\bf 7820}

Mazzali, P. et al., 2002, {\it ApJ Letters}, submitted

Meikle, P., Lucy, L., Smartt, S., Leibundgut, B., Lundqvist, P., Ostensen, R., 2002, {\it IAUCirc}, {\bf 7811}

Nakano, S., Kushida, R., Kushida, Y., Li W., 2002, {\it IAUCirc}, {\bf 7810}

Riffeser, A., Goessl, C.A., Ries, C., 2002, {\it IAUCirc}, {\bf 7825}

Sharina, M.E., Karachentsev, I.D., Tikhonov, N.A., 1996, {\it A\&AS}, {\bf
119}, 499

Smartt, S., Meikle, P., 2002, {\it IAUCirc}, {\bf 7822}

Vreeswijk, P., Smartt, S., 2002, {\it IAUCirc}, {\bf 7820}

Yoshii, Y., et al., 2002, {\it IAUCirc}, {\bf 7826}

\endreferences


\end{document}
 

