August 3, 2020: Calcium Trio

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August 3, 2020: Calcium Trio

Post by p_zetner »

Hi Everyone.

Weather and seeing conditions cooperated nicely for two consecutive days, the 3rd and 4th of August. On the 3rd, I managed a productive session with the spectroheliograph and am slowly processing the images. Here, I'm presenting the full disk in the light of the calcium ion at three wavelengths: the K line (3934 A), the H line (3968 A) and one of the infrared triplet lines (8498 A). This was the first time imaging in the infrared and poor planning led me to image the 8498 A component of the triplet as opposed to the stronger 8542 A line.

To my eye, the full disk view shows no obvious differences among the three lines. It's possible that the infrared triplet lines have something different to offer at higher image resolution but it's unlikely I'll be able to spot any differences with my instrument. I'll have to give the stronger triplet line a go in the future but need a new filter to accomplish this. Some order sorting with an Edmund Optics 850nm 10nm bandpass filter was required for the present image and the 8542 A line was right at the filter cutoff edge.

Hope you enjoy this preliminary output from the August 3rd session.
Cheers.
Peter
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Re: August 3, 2020: Calcium Trio

Post by Carbon60 »

Very nice, Peter. Amazingly similar across the spectrum.

Stu.


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Re: August 3, 2020: Calcium Trio

Post by Montana »

Wonderful images Peter, but I can't see much difference between the different calcium lines on the large scale.

:bow :hamster:

Alexandra


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Re: August 3, 2020: Calcium Trio

Post by Valery »

Hi Peter,

Very impressive results.

Yes, I still hope that with a narrower slit you will be able to detect some filamentary-like structures which makes
8542.1A images as a mixture of Ca and Ha images.

Keep my fingers crossed and wish you a luck. If you will accomplish this chanllenge task then this will be historical event
in amateur solar astrinomy. Go ahead!


Valery


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Re: August 3, 2020: Calcium Trio

Post by p_zetner »

Thanks for your comments everyone.

The calcium disks do look very similar but there may be a slight difference detectable which is consistent with what is observed by NSO. If you look closely at the infrared image, there is a faint "shadow" region around the bright plage. You can clearly see this effect in the NSO image at 8542A.

https://gong2.nso.edu/products/scaleVie ... uctIndex=7

This is the strongest of the three infrared triplet lines but was inaccessible to me because I had to use an interference filter for order sorting. I'll return to this line in the future and, hopefully, something new will be visible.

Cheers.
Peter


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Re: August 3, 2020: Calcium Trio

Post by marktownley »

Very impressive indeed Peter. I enjoy seeing your work with the spectroheliograph.


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Re: August 3, 2020: Calcium Trio

Post by solarGain »

Very detailed workings being shown here Peter. I am slowly building my 2nd SHG.
This one is a Littrow ala Fulvio Mete and I shall almost certainly use a 50mm x 50mm reflective holographic grating from Thorlabs. The extreme infraRed parameters for this grating collapse just beyond 825nm, so I must assume that you are using two gratings for your overall/ complete wavelength work is that correct?
It would be very useful to me to know what you are using if thats OK.
I won't have mine ready until the New Year if I'm lucky.
All the best
John


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Re: August 3, 2020: Calcium Trio

Post by p_zetner »

Hi John.
I used a single Dynasil / Optometrics 1800 groove, 25x50mm, holographic, UV blazed grating. The curve is attached to this post. I should also mention that I used a bandpass filter (Edmund Optics 850nm CWL, 10nm FWHM) to block a second order spectrum. Without the filter in place, the image contrast was abysmal.
This is the first time I've tried imaging in the infrared. In the past, I've most commonly used a 2400mm groove grating whose response didn't extend far enough into the IR (efficiency dropping to zero near 825nm).
You are building a 2nd SHG? I don't recall seeing any results from your first device. Have you posted any spectroheliograms?
Cheers.
Peter
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Re: August 3, 2020: Calcium Trio

Post by solarGain »

Peter Hi.
Thank you very much for the details and the curve.

In 2010, I was in deep discussions with Dave Groski for more than 3 years. I opted for the Clifton Horne’s SHS that appeared in a copy of Sky and Telescope, in October 1971.
It was fully built, my documentation of the build was poor compared to the build itself I learnt a great deal. Having said that its a folded system and I could never get the system to produce a coherent image, and then ran into a spiral of defeatism. This was all prior to taking up imaging. I had taken on too much. But I still have it.

I am deeply indebted to Dave who mentored me, and for all of his invaluable work in helping execute this SHS and inspiring me now with more time on my hands to finalising a linear system with a grating that folds the image back to a CMOS camera.

For several years now I have been using a robust mount, a Mesu 200, I only wished I had it in 2013.

All the best
John


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Re: August 3, 2020: Calcium Trio

Post by solarGain »

Oh, an image from 2014 in La Palma.
phpBB [media]

John
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