It does not become very much bright even getting closer to the sun.
However, it suddenly starts brightening very rapidly several months
prior to the perihelion passage, and reaches to the maximum brightness
only within two months or so.
In 2008, the beginning of the rapid brightening was delayed and the
maximum brightness was fainter than 2001.
Kazuo Kinoshita's calculation revealed that it passed 0.87 A.U. from
Jupiter in 1984, and the perihelion distance was reduced from 2.7
A.U. down to 2.45 A.U. However, it passes only 0.71 A.U. from Jupiter
again in 2023, and the perihelion distance will be increased up to 2.8
The current feature to brighten rapidly may disappear in the future
returns after 2035, and the comet may be much fainter than now.
Kazuo Kinoshita's calculation revealed that it passes 0.63 A.U. from
Jupiter in 2091, and the perihelion distance will be reduced down to
2.45 A.U. again.