An observation is impossible state for comet C/1999 S4. I end for chase of the brightness to have gone from last year. I show variation of the brightness parameters that guessed with observation datas hereinafter. By the way, the following brightness parameters doesn't include burst in the last ten days of June. As for that reason, C/1999 S4 brightness variation in those days is small, and dispersion of observation data is large. Brightness parameter (JD 2451751.36) is reference value since nuclear disintegration of comet occurred. JD 2451452.904 ~ 2451739.59 : m0 = 8.4, k = 7.5. JD 2451740.41 ~ 2451750.79 : m0 = 9.2, k = 5.0. JD 2451751.36 ~ : m0 = 41 , k = 275.
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http://www.aerith.net/index-j.html
ICQ : Recent Comet Brightness Estimates.
http://cfa-www.harvard.edu/iau/icq/CometMags.html
NASA : Recent News and Observations
http://encke.jpl.nasa.gov/RecentObs.html#99S4
芸西(372) : 芸西天文台通信<1999年10月25日号 他>
http://www2u.biglobe.ne.jp/~comet3/Tuusin/991025.html
天平の森 : 天平の森天文台撮影の彗星画像(C/1999 S4)
http://member.nifty.ne.jp/ynag/sub032.htm
NAG08 : NAG08 Comet Obs.
http://member.nifty.ne.jp/ynag/obs.htm
軌道要素出典: MPC MPC 40668 etc.