Comet Holmes

(fritz kleinhans)


Comet Holmes underwent a spectacular outburst Oct 24th, 2007.  Thanks to Shawn Grant for the heads up.  On the morning of Oct 25th the comet was readily visible to the naked eye from suburban Indianapolis (7.5 miles from town center).  It was between Alpha and Delta Perseus in brightness and thus about m = 2.5 with an obvious yellow color.  In 7x35 hand held binoculars it appeared slightly non-stellar. With 15x45 Canon IS binoculars it was clearly non stellar, (my very crude estimate is 3x the size of Jupiter or ~ 2 minutes diameter) with a disk shape.  The core is slightly brighter. Then at the edge of the disk, the brightness drops rapidly, giving the appearance of a relatively sharp edge.  No tail was apparent, or reported by others.  It has an 'unreal' appearance.

Holmes was visible for several months, throughout the night, with a constantly expanding shape.  It was readily visible into early 2008 and became absolutely huge.  One of the neatest comets ever to follow visually (naked eye and binoculars).  Because of its constantly changing appearance it presented a special photographic challenge.  How to get pictures of it on a continual basis and still have  a regular life.  I.e how to get up at 3 AM, shoot some quick pictures from my front yard in Indianapolis without ever changing out of my PJ's, and get back to bed in half an hour.  The solution was to just pop a camera on a regular photo tripod and shoot short exposures (2 sec) with out any guiding or tracking.  To go deep, lots of shots were stacked (60 to 200) yielding total exposure times of 2 min to 6 min 40 sec.  My sharpest, fastest lens is an 85 mm f1.4 AIS Nikkor.  It is sharp in the center and okay at the edges at f1.4, pretty good to the edges at f2, and excellent across the frame at f2.8.  The only shortcoming is the need for very precise focus, otherwise stars show red halos.  Since my Canon-Hutech 400D does not have live view, this was difficult (think dozens of shots, examined on the screen at 10 x mag with a 3 x hand lens, total mag = 30x) and many of my shots show red halos.  And of course, manually pushing the shutter button 150 times in quick succession would never do so a remote controller (Canon TC-80N3) was used.   Finally, I note that mirror lock up is not practical with the TC-80N3 and thus all the shots were taking with a 'slapping mirror'.  This has never proved to be a problem.

Comet Holmes:
 
Oct 2007-Jan 2008; Indianapolis, IN, USA

Canon Hutech 400D, ISO 400, 85 mm f1.4 AIS Nikkor at f2.0, 60 to 300 subs at 2 sec/sub = 2 min to 6.7 min. total.  Binned 2x2 yielding a final resolution of 27.6 arcsec/pixel.
Camera on standard photo tripod, no tracking, no guiding (Where was the Vixen Polarie when I needed it :-) ?)
Heavily processed.  Don't take the colors or intensity variations too seriously.