Closest to Earth on 5 Nov 2007 at 1.62AU.
Closest to Sun on 4 May 2007 at 2.05AU.
Maximum magnitude 2 in October 2007
Orbital period: 6.9 years

On October 24, 2007, this usually faint, distant comet 17P Holmes underwent a major outburst and rapidly rose to magnitude 2.


This photo was captured on the morning of Nov 10, 2007.
The comet was situated only 3 degrees above the northern horizon but still appeared spectacular through 25x100mm binoculars,
 
Since the outburst, the comet maintained a steady brightness, with the coma slowly expanding and becoming more diffuse.
It also became better situated for viewing in the southern hemisphere.

My observation with the unaided eye on 2008 January 4 indicated a magnitude of 3.5 and coma size of 1 x 1.3 degrees!

17P Holmes on 2008 Jan 4.48UT
5x3 min exposures. Canon 300D digital camera. 135mm zoom lens, cropped. The Star cluster M34 in Perseus is to the left.


17P Holmes on 2008 Jan 4.48UT
2x3 min exposures. Canon 300D digital camera. 200mm zoom lens, cropped.

The comet was still as bright as magnitude 4 during March 2008 but appeared large and very diffuse.
It was no longer observable from the southern hemisphere.

Below are my visual observations in ICQ format

17 2007 11 10.62 2:TK 5.0B 7 20 4 ICQ nn MAT08
17 2007 12 07.52 3.5:TK 5.0B 7 50 1 ICQ nn MAT08
17 2007 12 27.50 S 4:TK 10.0B 25 60 1 1.5 ICQ nn MAT08
17 2008 01 01.49 S 4:TK 4.0B 8 60 1 1.3 ICQ nn MAT08
17 2008 01 04.48 3.5:TK 0.0E 1 60 1 ICQ nn MAT08
17 071110.62 comet altitude three degrees. [MAT08]
17 071207.52 in 25x100mm B, observable streak running through centre of coma. [MAT08]