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asaint
Carpal Tunnel
Reged: 04/25/03
Posts: 2019
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December (2007) Skies
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StarStuff1
sage
Reged: 04/01/07
Posts: 428
Loc: East Tennessee
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Nice article. The last sentence in the first paragraph about Comet Holmes not being visible without binoculars caught my eye. I guess this means not naked eye visible. I have observed Holmes three nights in the past week naked eye from my side yard. Not real obvious but definitely there. Last night was clear but so many neighbors now have outside Christmas decorations turned on that the comet (along with many fainter stars) was washed out. It was faintly visible through 12X45 binoculars.
Terry
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Two dozen eyepieces, a dozen binoculars, a half dozen refractors, two reflectors and a homemade Image Intensifier Eyepiece (IIE). All products subject to change by the owner at any time.
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ScottAz
Fleet Navigator
Reged: 02/06/05
Posts: 1142
Loc: Millington, TN
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A very fine summary, that I much enjoyed reading. Thank you! These monthly guides are very helpful. 
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Scott Azmus
SV80BV, NexStar 11, & 18" Obsession 
Many Views Yield Truth
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kulginov
member
Reged: 11/10/05
Posts: 47
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<i>At that time, the disk will span almost 16 arcseconds and will fill about one half of the field of view in a medium power (100X) telescope eyepiece.</i>
Wrong calculation - less than a half of a degree.
Dmitri
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Pedestal
Post Laureate
Reged: 03/11/06
Posts: 3026
Loc: Smoggy Bottom, Baytown,Texas
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As usual, I really appreciate the summary of the Mars Rover activity!
Hubert
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www.smoggybottom.org
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CESDewar
GorillAstronomer
Reged: 01/16/05
Posts: 1802
Loc: Morganton, GA, USA
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not being visible without binoculars caught my eye too. It does need a qualifier, such as "from urban skies". I have dark skies up here in North GA, and Comet Holmes is a very obvious naked eye object and has been ever since the outburst. I was just out a few minutes ago and in spite of some high level clouds, it was still readily visible to the naked eye. Yes, it's obviously fading, but from here and at this rate, it will be a naked eye object for several weeks more.
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J_D_Metzger
Pooh-Bah
Reged: 05/13/04
Posts: 1301
Loc: Tucson, AZ
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"At that time, the disk will span almost 16 arcseconds and will fill about one half of the field of view in a medium power (100X) telescope eyepiece."
I have to agree with Dmitri, your calculation is way off. I think you confused arcseconds with arcminutes. At 100X, Mars will appear 100 * 16' = 1600', or about 27 arcminutes, or, as Dmitri pointed out, a little less than 1/2 degree. In a 50° AFOV plossl, it will subtend less than 1/100th of the field of view.
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Clear skies,
J.D.
32°15'16.96"N 110°47'39.24"W
Celestron C9.25 & C6, TeleVue TV-76,
Vixen Sphinx SXD, iOptron MiniTower
TeleVue Naglers, TeleVue Panoptics
Canon 10x30 IS Binoculars
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cookman
journeyman
Reged: 08/01/06
Posts: 7
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A 50° apparent field of view eyepiece provides a 0.5° field of view at 100x (50°/100=0.5°).
Mars will span 16 arcseconds. At 100x this is 1600 arcseconds or 0.44°. Therefore Mars almost fills the field of view of a medium power eyepiece —— whoops, that is 100x100 isn't it?
Well how about when looking through a telescopes on a spaceship which is 587,830 miles from Mars? I forgot to mention that in the article.
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J_D_Metzger
Pooh-Bah
Reged: 05/13/04
Posts: 1301
Loc: Tucson, AZ
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Quote:
Well how about when looking through a telescopes on a spaceship which is 587,830 miles from Mars? I forgot to mention that in the article.
Nice try.. 
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Clear skies,
J.D.
32°15'16.96"N 110°47'39.24"W
Celestron C9.25 & C6, TeleVue TV-76,
Vixen Sphinx SXD, iOptron MiniTower
TeleVue Naglers, TeleVue Panoptics
Canon 10x30 IS Binoculars
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Dick Rose
member
Reged: 09/25/07
Posts: 32
Loc: Orange Beach,AL
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This helps me out. So your saying the Orange dot is going to be bigger than all the white dots and more straight up? I'm catching on now.
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Orion ST120/Vixen P,10" Meade SCT/lxd55gt wi lxd75 Tripod, WO binos
Binocks: Barska 15x70,2 7x50s & 2 10x50s
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lunar-tic
member
Reged: 06/28/07
Posts: 32
Loc: Louisiana
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My experience is that Comet Holmes is still detectable naked eye. With 7x50 it is larger then the Moon. I compare its light with k Persei. 7x50 showed Holmes and M46 in the same field. In my location, where they have not started to erect new town homes I can regularly see M31, M44, without anything but my distance glasses. It was far brighter than M31 last night at 6:32 in my zip 20678. Sometimes the High School has their field lights on , then it's like urban pollution. But great article! - Ben
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Glasses, OS cataract, OD Off-center lens implant
BARSKA 15x70
Celestron C5 CG3 mount
Celestron C6 Newt f/5 slide focuser on Polaris mount short wooden legs
Meade 80mm f/11 Altaz manual mount
Coulter 10" f/5.35 mirror being refigured
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