Due to extreme sleep deficit, I had to pass up detailed observing and sketching this comet tonight. To the naked eye, it now is clearly non-stellar and appears as an extremely tiny disc. Through binoculars, it is slap-in-the-face obvious and cream colored. Through the low power 48X view, it now appears about as large as it did at 240X just 3 nights ago. The overall structure is similar to what I saw last night, although a new soft disc of brighter material seems to be clearer in the center surrounding the condensed fan structure. The outer halo still appears mottled. It's grown large enough that it's about ready to outgrow the 120X view.
Measurements with my astrometric eyepiece tonight yield:
- central condensation: 52 x 77 arc seconds
- coma: 310 arc seconds / 5.2 arc minutes
- outer halo: 682 arc seconds / 11.4 arc minutes
The moon is starting to slip away, so as it grows larger and the surface brightness starts to drop it should be a great time to observe under dark skies.
|Subject||17P / Holmes|
|Position*||Perseus: [RA: 03:50:00.8 / Dec: +50:21:11]|
|Size||Central condensation: 52 x 77 arc seconds|
Coma: 310 arc seconds / 5.2 arc minutes
Outer halo: 682 arc seconds / 11.4 arc minutes
|Brightness*||~ 2.5 vMag|
|Date/Time||October 27, 2007, 10:30 PM|
(October 28, 2007, 05:30 UT)
|Observing Loc.||Flagstaff, AZ - Home|
|Instrument||Orion XT8 (203 mm dia./1200 mm F/L)|
|Eyepieces/Mag.||25 mm Sirius PlÃ¶ssl (48X)|
10 mm Sirius PlÃ¶ssl + 2X Barlow (240X)
12 mm Meade Astrometric + 2X Barlow (~200X)
|Conditions||Clear, calm, gibbous moon|
|Transparency||~ Mag 4.5 NELM|
|*Sources||Aerith.net; Starry Night Pro Plus 5|
*Based on published data.