The light curve had been stable for a long time since its discovery in
1930 until 1995 August. The brightness had been along m1 = 11.5 + 5
log delta + 18.0 log r. The brightness evolution is rather fast.
The nucleus was split in 1995 August. The comet became in outburst,
brightened by 6 mag, and the absolute magnitude brightened up to 5.5
After the nuclear split, the brightness of the comet has been getting
fainter gradually by every return. The absolute magnitude was 5.5 mag
at outburst in 1995. Then it faded to 7.5 mag in the next return in
2001, and faded furthermore to 9.0 mag in 2006 at the recovery. During
the apparition in 2006, it faded down to 11.5 mag, and it has come back
completely to the original brightness.
If it passes the perihelion in June, it passes extremely close by the
earth and becomes extremely bright. It passed only 0.062 A.U. from the
earth in 1930, and it was discovered. It passed only 0.076 A.U. again
in 2006, and it became a naked eye comet.
In 2001, the first return after the nuclear split, two more
components, E and B, were also observed in addition to the main
component C. In 2006, two components, C and B, became so bright as
naked-eye objects, and so many tiny fragments were observed.