Something different, H13.

[Icosahedron]

Yesterday I was rewarded with the best atmospheric seeing so far this year so I dared an attempt at H13 (373.44 nm). Fairly pleased with the result.

 

Edited June 17, 2021 by Icosahedron

[vlaiv]

Very interesting.

Just for my benefit, that is Balmer series 13->2 transition, right?

According to this formula:

https://en.wikipedia.org/wiki/Balmer_series

Wavelength is 373.34nm. What sort of filter are you using to get this?

[Icosahedron]

Yes, that is correct (13->2). I'm using a spectroheliograph with a theoretical spectral resolution of 0.1 Angstrom.

I'm riddled with doubt now. Consulting Rowland's Solar Spectrum Wavelengths today I noted that there is a Fe I line at 373.48 nm. At the time I was on my feet and only armed with the wavelength of H13. I calibrated on the centre of Calcium K, did the hop from there under electronic control and recorded the line at the destination. Next time I'll confirm the presence of the Fe line first.

[Kitsunegari]

Looks like you need to move your optics for the UV end of the spectrum,  if you cannot get a clear image at 393nm you will have a heck of a time getting clarity out of 370nm.   There is a quite a bit of blur it appears compared to the h-alpha, you may need to adjust your focal point on the slit.  (or your primary telescope)

[Icosahedron]

Blurriness is the result of poor sensitivity of the image sensor in the UV. A longer exposure time is required during which seeing takes its toll. Here is a comparison of the sources which were acquired minutes apart. The horizontal lines show how seeing affects the shorter but not the longer wavelength. The well-defined squiggles in a few places show that focusing is not the problem.

 

Edited June 17, 2021 by Icosahedron

[callisto]

9 hours ago, vlaiv said:

Very interesting.

Just for my benefit, that is Balmer series 13->2 transition, right?

According to this formula:

https://en.wikipedia.org/wiki/Balmer_series

Wavelength is 373.34nm. What sort of filter are you using to get this?

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Edited June 17, 2021 by callisto
change wording

[inFINNity Deck]

Hi Icosahedron,

Impressive results! I presume you imaged it with the spectroheliograph you posted a while ago? The image quality has improved enormous since! 🙂 👍

Nicolàs

[Icosahedron]

This is definitely H12 (375.02 nm), note the bright spot in the southern hemisphere.

[Kitsunegari]

 

Try one of these.

455.4 

 553.54

[Icosahedron]

I tried the two Ba wavelengths and found them to appear the same as the continuum with a little less brightness. Any detail was probably lost in the seeing.

Here are a few captures from 17 July; H-alpha, beta, gamma and delta:

Fe I at 438.36 and Ca I at 422.67 nm as well: