An unexpected result with an 12nm H alpha filter

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ChrisHalpha2017
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An unexpected result with an 12nm H alpha filter

Post by ChrisHalpha2017 »

Hello,

as some of you know already I watch the solar prominences with a spectro-coronagraph (a coronagraph where the h alpha filter is replaced by a diffraction grating).
Two days ago I bought a 12 nanometer Ha filter for some experiments in my spectro. I used to use a high pass filter to isolate roughly the Ha from the rest of the spectrum. A red filter for the deep sky observation of around 60 -70 nm bandwidth ( 600-700 Angstroms).
Of course these kind of filters are not at all suited for solar observations as its far too dangerous for the eyes and the prominences wont be seen.

Still , I set my 12nm filter in the ASI 178MM and started to look for the Ha line on the screen of my laptop as I was starting my session of prominence observation this afternoon with this new filter.

Accidentally I first found the zero order of diffraction and on the screen appeared the image of the entrance slit of the spectro coronagraph. The LYOT stop was set properly in order to stop the instrumental light diffusion and then enhance the contrast.

Here is what I saw on the screen :
mode coro +++++_20230526_140648.942_UT.jpg
mode coro +++++_20230526_140648.942_UT.jpg (149.63 KiB) Viewed 346 times
mode coro +++best ++_20230526_140726.622_UT.jpg
mode coro +++best ++_20230526_140726.622_UT.jpg (55.04 KiB) Viewed 346 times
protu 2 mode coro_20230526_140534.770_UT.jpg
protu 2 mode coro_20230526_140534.770_UT.jpg (80.74 KiB) Viewed 346 times
So, in fact I could see the solar prominences with a 120 angstroms H alpha filter . I could see them with the CAMERA ONLY.

I tried visually and the prominence was visible but the contrast was much lower than the image with the camera.

I then tried (with the camera) with the wide band filter and no prominences could be seen.

It suprised by as usually the sky in Paris is so hazy that it s not supposed to allow this kind of observations with such a filter.

Here are the photos with my spectro coronagraph and the 1200 l/mm grating.
1200 tmm littrow  filtre 120 A_2++++++_20230526_135858.760_UT.jpg
1200 tmm littrow filtre 120 A_2++++++_20230526_135858.760_UT.jpg (68.07 KiB) Viewed 346 times
2e protu 600 tmm ++++_20230526_142300.414_UT.jpg
2e protu 600 tmm ++++_20230526_142300.414_UT.jpg (47.82 KiB) Viewed 346 times
Chris.


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Re: An unexpected result with an 12nm H alpha filter

Post by Simon2940 »

That is so awesome. It's stuff like this that just says how real the world can be and that we can actually see things and make discoveries.


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Re: An unexpected result with an 12nm H alpha filter

Post by DeepSolar64 »

It's amazing that you could see and image the prominences at such a wide bandpass. Superb!!

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Re: An unexpected result with an 12nm H alpha filter

Post by Dennis »

Interesting, what are the bright specks apart of the prominence? Dust?


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Re: An unexpected result with an 12nm H alpha filter

Post by marktownley »

Great result indeed!


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Re: An unexpected result with an 12nm H alpha filter

Post by george9 »

This is really good. Have you posted the design of your spectro-coronagraph?

This may be of interest, by Klaus_160. He took prominence images through a coronagraph and various filters, including no filter.
https://www.cloudynights.com/topic/7569 ... ominences/

George


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