Ca II K solar activity 30 Dec 2021

[Merlin66]

Managed to find a cable combo which would give me 150 fps with the MiniSHG.
Today's disk shows all the prominent AR's, sunspots and filaments.
The "protus" image shows the large and bright prom.
(Using a W47 + Astronomik L1 UV-IR + 1mm exit slit to suppress the background.)

[Eris]

Ken your Ca II K images show many interesting details. In particular I like that Prom shot. Oddly enough I to was out early this morning in an attempt to beat the heat of the day. After several close views of the limb I noticed your prom but it was exceedingly faint and buried in noise.
Also I had a similar thought last night re blocking filters and considered applying a UV rejection filter to help block out some UV leakage (if any) “fogging” the image. Now if I could lay my hands on the Astronomik L filter in that RGB filter set. Nothing ventured nothing gained.
Hopefully I will be able to make some time this afternoon and post what I’ve got for a prom comparison. I sense your result is way in front.

[Merlin66]

Gerard,
Thanks mate!
After fighting the problems of the USB3 cables all week, I was pleased to be able to record the prom.


I do think the Astronomik L1 UV-IR filter is a good move. I've never seen a transmission curve for the Lunt Ca filter, so there could well be some UV (and NIR) leakage which would be removed.


I now have a workable solution for H alpha and Ca II K/H. Just need some practise with the Na/ He/ Mg wavelengths. I do have a collection of green, yellow and other filters.
I'll probably give the MiniSHG a rest for a while and go back to my DIY 1A CaII K filter and the DS SM60.......

[Martin_S]

Ken , your Mini SHG is giving some great results, well done.

Martin.