Spectroheliograms from 15th Feb 2023

[Alun_H]

Couple of spectroheliograms taken earlier today in the CaK line and the CaK II 8542.1 line using my 72ED with Herschel wedge/Sol'Ex and QHY5III 178M.
Because of the limited travel in rotation with the 2400l/mm grating after having captured the CaK line scans I swapped it out for a 1200l/mm so as to allow access to the CaK II line,this grating has seen better days and seriously needs replacing due to the reflective coating breaking down,also added a Infrared Pass (807) filter to the front of the camera to act as an order filter. Reconstruction in SER MAIN Ver 3.7 and apart from resizing and rotation to
correct orientation no other processing has been carried out on these two single scans. x16 slew speed used on CEM60 to force the scan of the solar disk.

Alun

CaK-12_25_230215.jpg (84.57 KiB) Viewed 1259 times

CaK-II-8542a_14_33_230215.jpg (119.31 KiB) Viewed 1259 times

[Montana]

Wow!! interesting comparison

Alexandra

[thesmiths]

That's really good with 854.2nm. I was never able to do so well (I think my telescope triplet optics don't work well in the IR).

If you want to reduce the horizontal stripes in the Calcium images, I would recommend reducing the "transversalium correction strength" to 1.0 or lower. It is a kind of low pass filter and if there are very high contrast features, it causes the effect you see (particularly in the IR wavelength).

If you plan on getting a replacement for the 1200 l/mm grating, you might consider a 1800 l/mm.

[Alun_H]

Thank you Alexandra,Douglas.

I will play around with the transversalium correction tool as I must admit I have a tendency to leave it at around 1.8-2.0. Before I get another grating,and thanks for the tip on the 1800,I am going to try and extend the travel of the gratings rotation in an attempt to reach the IR with the 2400.

Alun

[thesmiths]

I am going to try and extend the travel of the gratings rotation in an attempt to reach the IR with the 2400.

It is in fact impossible. The angle goes beyond 90 degrees. See the SimSpec SHG spreadsheet.

[Alun_H]

It is in fact impossible. The angle goes beyond 90 degrees.

I found the angle will be too tight when I checked the grating holder,so the 1800l/mm grating will be added to the shopping list along with the filter
for my CaK module as well as the other astro bits I need

Alun

[marktownley]

Amazing stuff!

[Alun_H]

Thank you Mark.

Alun