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Old 30-10-2021, 12:11 PM
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Merlin66 (Ken)
Spectroscopy Wizard

Merlin66 is offline
Join Date: Oct 2005
Location: St Leonards, Vic
Posts: 8,651
Helium in the solar spectrum.

The emission line of He1 (known as D3) lies at 14.32A towards the blue from the D1 Sodium line (The doublet D1 and D2)
The intensity of the D3 line is only about 3% above the local continuum.
To make a visible image of the Sun in Helium the continuum image must be subtracted from an image acquired at D3.

According to SimSpec_SHG for the MiniSHG optics, the D3 line should be at 207.43 pixel below the D1 line.

The INTI software allows this offset to be entered (as well as a suitable offset to obtain a continuum image)
Initial trials today were washed out due to cloud and the limited SER videos obtained were overexposed. Bumma!

They did however verify the methodology and the "best" D3 seemed to be around 207 pixel offset. A couple of Helium "plumes" were easily visible.
(about 1 O'clock and six O'clock)

[Edit] When the slit is positioned at the extreme edge of the disk it's possible to see the D3 Helium line in the spectrum close by the D1 Sodium.
The D3 is the bright line and the D1 is the dark absorption line below.

Looks like cloud/ rain through to next Tuesday......
Onwards and Upwards.
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Last edited by Merlin66; 30-10-2021 at 01:53 PM.
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