Thanks Terry,

It was astonishing for me that the tail was still very long beyond my
expectation and had somewhat complex structure with irregularities. I hoped to
image some debris other than the tail-like structure, but I failed to image
them. There may remain some possibility to image them with faster optics and
tracking system, for example with Metcalf method, which I can not apply now with
my equipment.

I tried another extreme enhancement of the frame. I feel that this frame shows
greenish ion coma as in other bright comets.
http://www.flickr.com/photos/hiroc/6294440336/

I'd like to thank J.J.Gonzalez, who presented his visual observation of the
comet on October 21, 2011. I could enjoy imaging of the comet as an amateur for
more than a week since then.

hiro