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Date: 02 Oct 2006 15:27:20
From: Anthony Ayiomamitis
Subject: NGC 884 - Open Cluster in Perseus
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Dear Friends,
I would like to present you with last night's result involving the
impressive open cluster NGC 884 in Perseus and which forms one half of
the so-called "Double in Perseus". The result is based on two hours
total exposure.
http://www.perseus.gr/Astro-DSO-NGC-0884.htm
Clear skies!
Anthony.
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Date: 02 Oct 2006 09:28:27
From: atasselli@hotmail.com
Subject: Re: NGC 884 - Open Cluster in Perseus
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Anthony Ayiomamitis wrote:
> Dear Friends,
>
> I would like to present you with last night's result involving the
> impressive open cluster NGC 884 in Perseus and which forms one half of
> the so-called "Double in Perseus". The result is based on two hours
> total exposure.
>
> http://www.perseus.gr/Astro-DSO-NGC-0884.htm
>
> Clear skies!
>
2 hrs for a cluster and a bright one too??? Is there a reason?
Andrea T.
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Date: 02 Oct 2006 19:39:22
From: Anthony Ayiomamitis
Subject: Re: NGC 884 - Open Cluster in Perseus
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atasselli@hotmail.com wrote:
> Anthony Ayiomamitis wrote:
>
>>Dear Friends,
>>
>>I would like to present you with last night's result involving the
>>impressive open cluster NGC 884 in Perseus and which forms one half of
>>the so-called "Double in Perseus". The result is based on two hours
>>total exposure.
>>
>>http://www.perseus.gr/Astro-DSO-NGC-0884.htm
>>
>>Clear skies!
>>
>
>
Hi Andrea,
> 2 hrs for a cluster and a bright one too??? Is there a reason?
Just trying to maximize the S/N ratio as much as possible. I am not
worried about a couple of hours if I can get a really good result and
even if it happens to be with a trivial subject such as an open and
bright cluster.
Heck, if others can spend 20+ hrs on a deep-sky object, I do not have
the slightest problem with a couple of hours on a cluster.
Anthony.
>
> Andrea T.
>
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Date: 02 Oct 2006 10:27:48
From: Brian Tung
Subject: Re: NGC 884 - Open Cluster in Perseus
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Anthony Ayiomamitis wrote:
> Just trying to maximize the S/N ratio as much as possible. I am not
> worried about a couple of hours if I can get a really good result and
> even if it happens to be with a trivial subject such as an open and
> bright cluster.
>
> Heck, if others can spend 20+ hrs on a deep-sky object, I do not have
> the slightest problem with a couple of hours on a cluster.
Lucky you. Andrea even has problems when *other* people spend the two
hours. :)
--
Brian Tung <brian@isi.edu >
The Astronomy Corner at http://astro.isi.edu/
Unofficial C5+ Home Page at http://astro.isi.edu/c5plus/
The PleiadAtlas Home Page at http://astro.isi.edu/pleiadatlas/
My Own Personal FAQ (SAA) at http://astro.isi.edu/reference/faq.html
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Date: 02 Oct 2006 23:00:52
From: Trane Francks
Subject: Re: NGC 884 - Open Cluster in Perseus
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On 2006-10-02 21:27 +0900, Anthony Ayiomamitis wrote:
> http://www.perseus.gr/Astro-DSO-NGC-0884.htm
Anthony, beautiful work. As always. :-)
trane
--
/////////////////////////////////////////////////////////
// Trane Francks trane@gol.com Tokyo, Japan
// Practice random kindness and senseless acts of beauty.
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Date: 02 Oct 2006 14:28:40
From: atasselli@hotmail.com
Subject: Re: NGC 884 - Open Cluster in Perseus
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>
> Hi Andrea,
Hello Anthony,
>
> > 2 hrs for a cluster and a bright one too??? Is there a reason?
>
> Just trying to maximize the S/N ratio as much as possible. I am not
> worried about a couple of hours if I can get a really good result and
> even if it happens to be with a trivial subject such as an open and
> bright cluster.
Meaning no disrespect but I'd think of it being a bit of overkill, as
the s/n for stellar objects is already high with shorter exposures.
OTOH, for being rather long an exposure it doesn't look like is very
deep in the picture. I'd also add that I personally very much dislike
adding spikes to stars, as I find them very distracting and annoyingly
covering nearby stars.
>
> Heck, if others can spend 20+ hrs on a deep-sky object, I do not have
> the slightest problem with a couple of hours on a cluster.
Fair enough. I just wondered whether there was any specific reason.
Apparently there's none.
Andrea T.
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Date: 02 Oct 2006 21:21:44
From: Iordani
Subject: Re: NGC 884 - Open Cluster in Perseus
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Anthony Ayiomamitis wrote:
> Dear Friends,
>
> I would like to present you with last night's result involving the
> impressive open cluster NGC 884 in Perseus and which forms one half of
> the so-called "Double in Perseus". The result is based on two hours
> total exposure.
>
> http://www.perseus.gr/Astro-DSO-NGC-0884.htm
Really beautiful! Brings out the orange/yellow ones quite nice. I "found"
the double cluster for the first time 2 weeks ago and went Wow! at the
eyepiece. Did a 4 x 120 mins, but it somehow doesn't quite match yours :)
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Date: 04 Oct 2006 16:54:24
From: Bill Tschumy
Subject: Re: NGC 884 - Open Cluster in Perseus
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On Mon, 2 2006 07:27:20 -0500, Anthony Ayiomamitis wrote
(in article <efr0jf$aur$1@mouse.otenet.gr >):
> Dear Friends,
>
> I would like to present you with last night's result involving the
> impressive open cluster NGC 884 in Perseus and which forms one half of
> the so-called "Double in Perseus". The result is based on two hours
> total exposure.
>
> http://www.perseus.gr/Astro-DSO-NGC-0884.htm
>
> Clear skies!
>
> Anthony.
The page indicates this was taken with an AP 160 refractor. What's causing
the diffraction spikes in the image?
--
Bill Tschumy
Think Astronomy -- Austin, TX
http://www.thinkastronomy.com
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Date: 05 Oct 2006 01:12:56
From: William R. Mattil
Subject: Re: NGC 884 - Open Cluster in Perseus
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Bill Tschumy wrote:
> The page indicates this was taken with an AP 160 refractor. What's causing
> the diffraction spikes in the image?
>
Probably created by the imager when they string thread or wire across
the aperture because many imagers like diffraction spikes.
http://www.celestial-images.com/Images/Orion-FSQ-1.html
4 Inch Refractor with wire across the front.
Regards
Bill
--
William R. Mattil : http://www.celestial-images.com
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Date: 07 Oct 2006 15:54:12
From: Stephen Paul
Subject: Re: NGC 884 - Open Cluster in Perseus
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William R. Mattil wrote:
> http://www.celestial-images.com/Images/Orion-FSQ-1.html
> 4 Inch Refractor with wire across the front.
Hi Bill,
Thanks for the new desktop wallpaper!!
I got my used GEG, and man, when they say giant, they're not kidding.
I ordered a Celestron adapter for it from Telescopes.com today. Hope to
have it all up and running with dark, clear evening (or early morning)
skies sometime soon.
Do you know what the actual focal length is with the C11, the GEG
set to the F4 position, and the camera sensor 158mm back from the reducer?
I think it's about 1545mm.
Flr = 292mm (measured)
D = 158mm
R = 1 - D/Flr
R = 0.46
2800mm at F10 = > 3360mm at F12
(used the TeleVue F12 estimate for 5" BinoVue back focus as a guess)
3360mm * 0.46 = 1545mm
1545mm
Thanks,
Steve
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