NEW direction in the solar narrowband imaging.

Use this section to discuss "standard" Baader/Coronado/ Lunt SolarView/ Daystar, etc… filters, cameras and scopes. No mods, just questions/ answers and reviews.
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Merlin66
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Re: NEW direction in the solar narrowband imaging.

Post by Merlin66 » Tue Jul 10, 2018 5:39 am

Quick update - the weather has been absolutely terrible - clouds, clouds and wind, rain...repeat....
I did manage to set up the Spectra-L200 with a 1200 l/mm grating, resolution around 0.7A and get the CaK II lines focused in the NIR. Needed a red sort filter to suppress the 2nd order spectrum. Just used the bright (!!???) sky as a target. A good first step.

Then set up the SM60/ED80 without the blocking filter with the Spectra-L200 attached.....not very good....I had "issues" getting the spectrograph to sit nicely in the ED80 ( I ABSOLUTELY hate those 2" to T thread adaptors with the ""safety recess" feature - should be called un-safe feature...a royal PITA!) the SM60 resonance lines were visible around the CaKII lines (8542/8662A) but need an improved set-up to get the clarity needed for analysis. Now the set-up is ready (!) next opportunity should deliver some results.
Stay tuned.
"Astronomical Spectroscopy - The Final Frontier" - to boldly go where few amateurs have gone before
https://groups.yahoo.com/neo/groups/ast ... scopy/info
"Astronomical Spectroscopy for Amateurs" and
"Imaging Sunlight - using a digital spectroheliograph" - Springer

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Merlin66
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Re: NEW direction in the solar narrowband imaging.

Post by Merlin66 » Fri Jul 13, 2018 3:14 am

No sun, but bright cloud (!!)
The illustration below shows the SM60 etalon bands and the CaK II absorption lines.

Not good news...
The FWHM of the bands is 7A in this region...finesse 18.7A and the tilt adjustment gives 1.2A towards the blue.

Any comment/ feedback?
SM60ED80_CaK II.JPG
SM60ED80_CaK II.JPG (109.41 KiB) Viewed 372 times
"Astronomical Spectroscopy - The Final Frontier" - to boldly go where few amateurs have gone before
https://groups.yahoo.com/neo/groups/ast ... scopy/info
"Astronomical Spectroscopy for Amateurs" and
"Imaging Sunlight - using a digital spectroheliograph" - Springer

mdwmark
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Re: NEW direction in the solar narrowband imaging.

Post by mdwmark » Sat Jul 14, 2018 1:08 am

That is what I though it would look like. I guested 24Ang peak separation.
Attached is a coating design for Ha. The narrower peaks will be where the transmission is the highest. As the transmission drops the HW will broaden and the bottom of the curve will not be near zero.
etalon mirror Ha.gif
etalon mirror Ha.gif (9.62 KiB) Viewed 343 times

mdwmark
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Re: NEW direction in the solar narrowband imaging.

Post by mdwmark » Sun Jul 15, 2018 5:57 am

The graph is for a simple 1/4 wave design. The high end etalons for solar will use a broad band mirror. So they are usually from K-line to Ha or Ha to the Ca lines in the IR.
The broad band mirrors will have more layers which means a higher cost.
Mark W.

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