Re: [Utah-astronomy] New Zealand Dark Sky
Hi Erik, I refurbished a 24" telescope on Mt John last spring. The sky is very dark but the seeing is not as good because Mt. John is situated in a valley with high mountains on each side and the down slope winds stir up the air. The telescope we were refurbishing was an old Optical Craftsman mount and Arne Henden (AAVSO director), Dirk Terrell (SWRI, Colorado) and I went down to bring the telescope up to modern control standards and fitting it with the capability to be operated remotely by the AAVSO. The mountain has a 1.8m telescope used for micro-lensing events, a 1 meter used for follow-up work the 24" AAVSO scope, a 24" Boller & Chivens and a 16" used by an organization called Earth & Sky that gives star parties on selected nights. A link to the University of Canterbury, Department of Physics is here: http://www.phys.canterbury.ac.nz/research/mt_john/index.shtml Some images that Dirk took while we were there are here: http://www.boulder.swri.edu/~terrell/images/nz2008mar/ Image #4 of this set is Arne & I looking over the Lake Tekapo and image #3 & #22 are the 24" telescope we were re-furbishing. A link to Earth & Sky is here: http://www.earthandsky.co.nz/ NZ is a beautiful place with the South Island outstanding. Cindy & I spent 7 days touring after we finished the work on the telescope. Jerry Foote ScopeCraft, Inc. 4175 E. Red Cliffs Dr. Kanab, UT 84741 435-899-1255 jfoote@scopecraft.com
Hi, Can anybody tell me right off-hand how many arc-minutes the night sky is? Thanks, Joe
That would depend on which way you are measuring. Going from the horizon (assuming a flat horizon) to the zenith and back down to the opposite horizon would be 180 degrees. Multiply times 60 (60 arc minutes per degree) = 10,800 arc minutes. But measuring around the horizon is 360 degree or 21,600 arc minutes. patrick On 08 Feb 2009, at 22:29, Joe Bauman wrote:
Hi, Can anybody tell me right off-hand how many arc-minutes the night sky is? Thanks, Joe
Many thanks, Patrick. Does it make sense to multiply the two to arrive at the total number of square arc-minutes? Best wishes, Joe --- On Sun, 2/8/09, Patrick Wiggins <paw@wirelessbeehive.com> wrote: From: Patrick Wiggins <paw@wirelessbeehive.com> Subject: Re: [Utah-astronomy] quick question To: "Utah Astronomy" <utah-astronomy@mailman.xmission.com> Date: Sunday, February 8, 2009, 10:41 PM That would depend on which way you are measuring. Going from the horizon (assuming a flat horizon) to the zenith and back down to the opposite horizon would be 180 degrees. Multiply times 60 (60 arc minutes per degree) = 10,800 arc minutes. But measuring around the horizon is 360 degree or 21,600 arc minutes. patrick On 08 Feb 2009, at 22:29, Joe Bauman wrote:
Hi, Can anybody tell me right off-hand how many arc-minutes the night sky is? Thanks, Joe
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On a small scale I think that would be ok. But keep in mind the further away from the horizon (in an Alt-Azi scale) the smaller each of those "squares" will get since while the vertical dimension will remain the same all the way to the zenith, the horizontal will shrink to nothing at the zenith. patrick On 08 Feb 2009, at 22:47, Joe Bauman wrote:
Many thanks, Patrick. Does it make sense to multiply the two to arrive at the total number of square arc-minutes? Best wishes, Joe
--- On Sun, 2/8/09, Patrick Wiggins <paw@wirelessbeehive.com> wrote: From: Patrick Wiggins <paw@wirelessbeehive.com> Subject: Re: [Utah-astronomy] quick question To: "Utah Astronomy" <utah-astronomy@mailman.xmission.com> Date: Sunday, February 8, 2009, 10:41 PM
That would depend on which way you are measuring.
Going from the horizon (assuming a flat horizon) to the zenith and back down to the opposite horizon would be 180 degrees. Multiply times 60 (60 arc minutes per degree) = 10,800 arc minutes.
But measuring around the horizon is 360 degree or 21,600 arc minutes.
patrick
On 08 Feb 2009, at 22:29, Joe Bauman wrote:
Hi, Can anybody tell me right off-hand how many arc-minutes the night sky is? Thanks, Joe
Patrick is describing polar coordinates, where the actual area subtended by a square minute-of-arc gets smaller as declination increases (gets closer to the poles), because the circle of right-ascension gets smaller. The alt-az example is polar coordinates used in a non-equatorial mode. Now, if describing the true FOV of an eyepiece, for example, or say, the apparent diameter of the moon, the definition of M.O.A. is typically the equatorial, or greatest, value. On Sun, Feb 8, 2009 at 10:58 PM, Patrick Wiggins <paw@wirelessbeehive.com>wrote:
On a small scale I think that would be ok. But keep in mind the further away from the horizon (in an Alt-Azi scale) the smaller each of those "squares" will get since while the vertical dimension will remain the same all the way to the zenith, the horizontal will shrink to nothing at the zenith.
patrick
On 08 Feb 2009, at 22:47, Joe Bauman wrote:
Many thanks, Patrick. Does it make sense to multiply the two to arrive at the total number of square arc-minutes? Best wishes, Joe
--- On Sun, 2/8/09, Patrick Wiggins <paw@wirelessbeehive.com> wrote: From: Patrick Wiggins <paw@wirelessbeehive.com> Subject: Re: [Utah-astronomy] quick question To: "Utah Astronomy" <utah-astronomy@mailman.xmission.com> Date: Sunday, February 8, 2009, 10:41 PM
That would depend on which way you are measuring.
Going from the horizon (assuming a flat horizon) to the zenith and back down to the opposite horizon would be 180 degrees. Multiply times 60 (60 arc minutes per degree) = 10,800 arc minutes.
But measuring around the horizon is 360 degree or 21,600 arc minutes.
patrick
On 08 Feb 2009, at 22:29, Joe Bauman wrote:
Hi, Can anybody tell me right off-hand how many arc-minutes the night sky is? Thanks, Joe
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Joe: On the entire sky there are 41,252.96127 square degrees. That's 148,510,660.6 square arc minutes. Or exactly 129600 x 3600 / PI. Or 4 x 180 x 180 x 60 x 60 / PI. These numbers derive from the fact that surface of a sphere is 4 times the area of a circle of the same radius and thus equal to 4 time PI in square radians and a square radian is (180/PI)squared degrees and a square degree is 60 squared square arc minutes. Of course the part of the sky above the horizon at any one time is only half that number. DT --- On Sun, 2/8/09, Joe Bauman <josephmbauman@yahoo.com> wrote:
From: Joe Bauman <josephmbauman@yahoo.com> Subject: Re: [Utah-astronomy] quick question To: "Utah Astronomy" <utah-astronomy@mailman.xmission.com> Date: Sunday, February 8, 2009, 9:47 PM Many thanks, Patrick. Does it make sense to multiply the two to arrive at the total number of square arc-minutes? Best wishes, Joe
--- On Sun, 2/8/09, Patrick Wiggins <paw@wirelessbeehive.com> wrote: From: Patrick Wiggins <paw@wirelessbeehive.com> Subject: Re: [Utah-astronomy] quick question To: "Utah Astronomy" <utah-astronomy@mailman.xmission.com> Date: Sunday, February 8, 2009, 10:41 PM
That would depend on which way you are measuring.
Going from the horizon (assuming a flat horizon) to the zenith and back down to the opposite horizon would be 180 degrees. Multiply times 60 (60 arc minutes per degree) = 10,800 arc minutes.
But measuring around the horizon is 360 degree or 21,600 arc minutes.
patrick
On 08 Feb 2009, at 22:29, Joe Bauman wrote:
Hi, Can anybody tell me right off-hand how many arc-minutes the night sky is? Thanks, Joe
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Thanks, Daniel. -- Joe --- On Mon, 2/9/09, daniel turner <outwest112@yahoo.com> wrote: From: daniel turner <outwest112@yahoo.com> Subject: Re: [Utah-astronomy] quick question To: "Utah Astronomy" <utah-astronomy@mailman.xmission.com> Date: Monday, February 9, 2009, 2:48 PM Joe: On the entire sky there are 41,252.96127 square degrees. That's 148,510,660.6 square arc minutes. Or exactly 129600 x 3600 / PI. Or 4 x 180 x 180 x 60 x 60 / PI. These numbers derive from the fact that surface of a sphere is 4 times the area of a circle of the same radius and thus equal to 4 time PI in square radians and a square radian is (180/PI)squared degrees and a square degree is 60 squared square arc minutes. Of course the part of the sky above the horizon at any one time is only half that number. DT --- On Sun, 2/8/09, Joe Bauman <josephmbauman@yahoo.com> wrote:
From: Joe Bauman <josephmbauman@yahoo.com> Subject: Re: [Utah-astronomy] quick question To: "Utah Astronomy" <utah-astronomy@mailman.xmission.com> Date: Sunday, February 8, 2009, 9:47 PM Many thanks, Patrick. Does it make sense to multiply the two to arrive at the total number of square arc-minutes? Best wishes, Joe
--- On Sun, 2/8/09, Patrick Wiggins <paw@wirelessbeehive.com> wrote: From: Patrick Wiggins <paw@wirelessbeehive.com> Subject: Re: [Utah-astronomy] quick question To: "Utah Astronomy" <utah-astronomy@mailman.xmission.com> Date: Sunday, February 8, 2009, 10:41 PM
That would depend on which way you are measuring.
Going from the horizon (assuming a flat horizon) to the zenith and back down to the opposite horizon would be 180 degrees. Multiply times 60 (60 arc minutes per degree) = 10,800 arc minutes.
But measuring around the horizon is 360 degree or 21,600 arc minutes.
patrick
On 08 Feb 2009, at 22:29, Joe Bauman wrote:
Hi, Can anybody tell me right off-hand how many arc-minutes the night sky is? Thanks, Joe
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Hi Jerry,
Thanks for more info. Sounds like a good perk of your business to travel to New Zealand. Your site is pretty dark also, you could always open an Astronomy Bed&Breakfast. Erik Hi Erik,
I refurbished a 24" telescope on Mt John last spring. The sky is very dark but the seeing is not as good because Mt. John is situated in a valley with high mountains on each side and the down slope winds stir up the air.
The telescope we were refurbishing was an old Optical Craftsman mount and Arne Henden (AAVSO director), Dirk Terrell (SWRI, Colorado) and I went down to bring the telescope up to modern control standards and fitting it with the capability to be operated remotely by the AAVSO.
The mountain has a 1.8m telescope used for micro-lensing events, a 1 meter used for follow-up work the 24" AAVSO scope, a 24" Boller & Chivens and a 16" used by an organization called Earth & Sky that gives star parties on selected nights.
A link to the University of Canterbury, Department of Physics is here:
http://www.phys.canterbury.ac.nz/research/mt_john/index.shtml
Some images that Dirk took while we were there are here:
http://www.boulder.swri.edu/~terrell/images/nz2008mar/
Image #4 of this set is Arne & I looking over the Lake Tekapo and image #3 & #22 are the 24" telescope we were re-furbishing.
A link to Earth & Sky is here:
NZ is a beautiful place with the South Island outstanding. Cindy & I spent 7 days touring after we finished the work on the telescope.
Jerry Foote ScopeCraft, Inc. 4175 E. Red Cliffs Dr. Kanab, UT 84741 435-899-1255 jfoote@scopecraft.com
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participants (6)
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Chuck Hards -
daniel turner -
erikhansen＠TheBlueZone.net -
Jerry Foote -
Joe Bauman -
Patrick Wiggins