November 8, 2007
17P / Holmes - NOV 7, 2007
Move mouse over sketch above to view labels. Click image for larger version.
Move mouse over sketch above to view labels. Click image for larger version.
Observation Notes:
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 | |
| Classification | Comet | |
| 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 Plössl 25 mm Sirius Plössl (48X) 10 mm Sirius Plössl (120X) 12 mm Meade Astrometric (~100X) | |
| Conditions | Calm, intermittent high cirrus | |
| Seeing | 4/10 Pickering | |
| Transparency | Mag 6.0 NELM | |
| *Sources | Aerith.net; Starry Night Pro Plus 5 |
*Based on published data.
Posted by Jeremy at November 8, 2007 3:04 AM .
Comments
Great Holmes pics! This blog is going on my blogroll!
Posted by: Rick at November 17, 2007 8:00 AM
Rick, thanks very much for your comment. I just had a chance to browse your site. Great work! It's easy to navigate, with great imagery and content. I'll add it to my links page shortly.
Posted by: Jeremy Perez at January 7, 2008 3:06 PM
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