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\IBVShead{4992}{1 December 2000}

\IBVStitle{II Pegasi Reached The Largest Amplitude Up To Now}

\IBVSauth{Ta\c{s}, G.; Evren, S.}

\IBVSinsto{Ege University Observatory, 35100 Bornova, Izmir, Turkey\\ \indent
e-mail: tas@alpha.sci.ege.edu.tr, sevren@astronomy.sci.ege.edu.tr}

\SIMBADobjAlias{II Peg}{HD 224085}

\begintext

\IBVSTnam{II Peg = BD\, +27\deg4642 = HD 224085 }

\IBVSTcoo{23\hr 55\mm 04\fsec05}{28\deg 38\farcm02}{2000}

\IBVSTobs{Ege University Observatory, 48-cm Cassegrain telescope}

\IBVSTdet{Hamamatsu, R4457 (PMT)}

\IBVSTfil{$U$, $B$, $V$ and $R$ filters of Johnson system}

\IBVSTcomp{BD\,+28\deg 4666 = SAO 91574}

\IBVSTchk{BD\,+27\deg 4648  = SAO 91593}

\IBVSTdata{Upon request}

\IBVSTtyp{ RS CVn }

\IBVSTrem{
II Pegasi is known as one of the most active RS CVn stars, which shows
significant photometric variability due to rotational modulation of
cool spots. The present observations of II Peg were obtained on 23
nights in 2000. We obtained 257 data points for each colour between
July 3 and November 17, 2000. Johnson $V$-band light curve for II Peg
obtained in this year is shown in Figure~1. Phasing is from  HJD
2449582.9268 with 6\fday724333 period (Berdyugina {\it et al.}\ 1998).
The brightness of the system reaches its maximum value at about phase
0.84 and its minimum value at about phase 0.42. Our broad-band
photometry shows $V$-band variations up to 0.63 mag. This value is the
largest amplitude value observed up to now. The system has diminished
until 8.04 mag in $V$-band at the first time. The smallest amplitude of
0.05 mag in $V$ was observed on II Peg in 1983 by Evren (1988). The
largest amplitudes of 0.50 mag in $V$ were observed previously in late
1986 by Doyle {\it et al.}\ (1988) and in early 1989 by Casas {\it et
al.}\ (1989).}

\IBVSfig{10cm}{4992-f1.ps}

\references

Berdyugina, S.V., Jankov, S., Ilyin, I., Tuominen, I., and Fekel, F.C.,
1998, {\it A\&A}, {\bf334}, 863

Casas, R., Gomez-Forrellad, J.M., and Tomas, L., 1989, {\it IBVS}, No.\ 3330

Doyle, J.G., Butler, C.J., Morrison, L.V., and Gibbs, P., 1988, {\it
A\&A}, {\bf192}, 275

Evren, S., 1988, {\it Astrophys.\ Space Sci.}, {\bf 143}, 123

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