I am making a prototype coronagraph.
However, I have not obtained sufficient results.
The filter I'm using now is Andover Corp's 10A H-alpha.
Does anyone know of a company that sells filters of about 5A?
Merrill55
Coronagraph
- Bob Yoesle
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Re: Coronagraph
Since you're talking H alpha filters, it seems you're talking about a solar prominence telescope (e.g. the chromosphere), not a coronagraph. There's a huge difference.
https://en.wikipedia.org/wiki/Coronagraph
You may want to review this couple of threads on Cloudy Nights:
https://www.cloudynights.com/topic/6425 ... velengths/
https://www.cloudynights.com/topic/7403 ... yesterday/
The best emission line for a corona filter would be the Fe XIV line at ~ 530.3 nm:
http://www.zam.fme.vutbr.cz/~druck/ecli ... 0-info.htm
There's a much more complicated need for perfectly polished optics, occulting discs, and high altitudes free of dust and other light scattering issues to make a true coronagraph:
https://en.wikipedia.org/wiki/Coronagraph
You may want to review this couple of threads on Cloudy Nights:
https://www.cloudynights.com/topic/6425 ... velengths/
https://www.cloudynights.com/topic/7403 ... yesterday/
The best emission line for a corona filter would be the Fe XIV line at ~ 530.3 nm:
http://www.zam.fme.vutbr.cz/~druck/ecli ... 0-info.htm
There's a much more complicated need for perfectly polished optics, occulting discs, and high altitudes free of dust and other light scattering issues to make a true coronagraph:
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Re: Coronagraph
Thank you for your reply.
Of course, coronagraph and prominence scope I understand the difference.
I can't observe the corona with Pic du Midi.
The scope with the interference filter removed is a complete coronagraph.
I would like to see prominence in a wider range of wavelengths.
I used a blocking filter to see if I could see the prominence. But it was a disappointing result. I can't see it at all.
Blocking filter seems to have a different structure from the multi-layer interference filter for prominence.
The combination of Andover Corp's 10A Ha filter and Edmunds' 100A Ha filter It provides a minimal amount of prominence images.
If I have a chance next time, I would like to try two 10A filters on top of each other.
Merrill55
Of course, coronagraph and prominence scope I understand the difference.
I can't observe the corona with Pic du Midi.
The scope with the interference filter removed is a complete coronagraph.
I would like to see prominence in a wider range of wavelengths.
I used a blocking filter to see if I could see the prominence. But it was a disappointing result. I can't see it at all.
Blocking filter seems to have a different structure from the multi-layer interference filter for prominence.
The combination of Andover Corp's 10A Ha filter and Edmunds' 100A Ha filter It provides a minimal amount of prominence images.
If I have a chance next time, I would like to try two 10A filters on top of each other.
Merrill55
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Re: Coronagraph
Rondi 's Coronagraph site is as follows;
http://www.astrosurf.com/rondi/coro/
My prominence scope is same as this.
http://www.astrosurf.com/rondi/coro/
My prominence scope is same as this.
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Re: Coronagraph
Hi Merrill,
I own a Baader Coronagraph and recently had it refurbished by Wolfgang Lille. He replaced my Halpha filter so I expect he could supply you with the filters you require?
viewtopic.php?f=10&t=28709
viewtopic.php?f=10&t=27490&p=248471&hil ... ng#p248471
Alexandra
I own a Baader Coronagraph and recently had it refurbished by Wolfgang Lille. He replaced my Halpha filter so I expect he could supply you with the filters you require?
viewtopic.php?f=10&t=28709
viewtopic.php?f=10&t=27490&p=248471&hil ... ng#p248471
Alexandra
Re: Coronagraph
I am pretty sure Wolfgang Lille uses Lunt blocking filters for refurbishing Baader prominence viewers these days. Baader had used soft-coated 1.5A-filters that are no longer available. Contacting Wolfgang is a good idea, he is very friendly and knowledgeable.
Frank
Frank
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Re: Coronagraph
Andover Corporation makes semi-custom interference filters.
However, it exceeds 2000 dollars at 25 mm diameter 0.5 nm.
However, it exceeds 2000 dollars at 25 mm diameter 0.5 nm.
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Re: Coronagraph
The original Baader coronagraph with its occulting cone used a 10A H-alpha filter and worked well.
Without an occulting cone, 10A is too wide, and I suspect 5A is, too. Most prominence filters I know of use 2A.
I don't find that prominences look better in my 2A filter than in my 0.5A double stack or in my 0.3A single stack. So I don't bother with it. But it was interesting to try.
My next goal is to see prominences in their more natural colors, which means using an occulting cone and passing a series of wavelengths.
George
Without an occulting cone, 10A is too wide, and I suspect 5A is, too. Most prominence filters I know of use 2A.
I don't find that prominences look better in my 2A filter than in my 0.5A double stack or in my 0.3A single stack. So I don't bother with it. But it was interesting to try.
My next goal is to see prominences in their more natural colors, which means using an occulting cone and passing a series of wavelengths.
George