As the comet has gotten larger, the outer envelope has become much less distinct. It shows up as a faint brightening near the inner envelope that fades imperceptibly into the background. The inner envelope has almost outgrown my 24 arc-minute wide 120X view. To the naked eye, it is a large, soft spot in Perseus. The binocular view is getting better as it moves closer to the Alpha Persei association and they fit in the field more comfortably.
Through both binoculars and low power telescopic views, the comet is a bluish green color. The pseudo nucleus is much less distinct, but still visible even at 38X. The inner envelope is now soft enough on the southeast side that this half displays a sort of blinking effect between direct and averted vision. The jellyfish appearance is still there, but now I can also see an ancient trilobite in the shape of the comet. The lumpy irregularities in the central condensation seem more spread out now, and had what looked like a cartoon saguaro cactus arrangement. At 38X, I noticed a bright extension flowing away from the axis of the central condensation, well outside of the soft inner envelope. Some softer fan-like extensions also seemed to peel away from the southeast and northwest sides of the inner envelope.
My measurements with the astrometric eyepiece are as follows:
- Central Condensation: 3.7 x 5.1 arc minutes
- Inner Envelope: 18.7 x 20.7 arc minutes
- Outer Envelope: 80 arc minutes
|Subject||17P / Holmes|
|Position*||04:00 UT – Perseus: [RA: 03:37:56.2 / Dec: +50:38:10]|
|Size||Central condensation: 3.7 x 5.1 arc minutes
Inner Envelope: 18.7 x 20.7 arc minutes
Outer Envelope: 80 arc minutes
|Brightness*||~ 2.6 vMag|
|Date/Time||November 7, 2007, 9:00 – 11:30 PM
(November 8, 2007, 04:00 – 06:00 UT)
|Observing Loc.||Flagstaff, AZ – Home|
|Instrument||Orion XT8 (203 mm dia./1200 mm F/L) / 15 x 70 Oberwerk Binoculars|
|Eyepieces/Mag.||32 mm Sirius PlÃ¶ssl
25 mm Sirius PlÃ¶ssl (48X)
10 mm Sirius PlÃ¶ssl (120X)
12 mm Meade Astrometric (~100X)
|Conditions||Calm, intermittent high cirrus|
|Transparency||Mag 6.0 NELM|
|*Sources||Aerith.net; Starry Night Pro Plus 5|
*Based on published data.