17P / Holmes – DEC 06, 2007

Step 1

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Observation Notes:

It’s hard to believe that it’s been a month since I last sketched this comet. It has truly become monstrous. To the naked eye, it is a large soft patch glowing in Perseus, and is still an incredible thing through binoculars. I no longer see any color in it–just a pale gray. It still possesses that trilobite appearance, but is much softer now. There is no visible pseudonucleus, and the central fan has become a soft spine. It looks to me like the southwest half of the coma is brighter.

Using the astrometric eyepiece for measurements has been out of the question for some time now. Based on my sketch and comparison to the star field in Starry Nights Pro, I made some rough estimates:

  • Central Fan: 12 x 60 arc minutes
  • Coma: 60 x 75 arc minutes
Subject 17P / Holmes
Classification Comet
Position* 04:00 UT – Perseus: [RA: 03:06:57.2 / Dec: +48:13:53]
Size Central Fan: 12 x 60 arc minutes
Coma: 60 x 75 arc minutes
Brightness* ~ 3.0 vMag
Date/Time December 6, 2007, 9:30 PM
(December 7, 2007, 04:30 UT)
Observing Loc. Flagstaff, AZ – Home
Instrument 15 x 70 Oberwerk Binoculars
Conditions Clear, breezy
Seeing 4/10 Pickering
Transparency Mag 6.0 NELM
*Sources Aerith.net; Starry Night Pro Plus 5

*Based on published data.