Hbeta & Halpha 30th March 2023

[Alun_H]

A couple of spectroheliograms from my session back on the 30th March. Once again hampered by clouds and having to wait for the odd gap big enough to allow me to run a scan at 16x sidereal on the CEM60,I got these two single scan images with the 72ED and Sol'Ex SHG with 9 micron quartz slit/QHY5III 178M in the Halpha and Hbeta lines. Slight processing carried out on both (sharpening,brightness/gamma levels,flip/rotation and resize),72ED was reduced to 40mm f/10 for the Hbeta.

Alun

13_01_59Z_shift=0_clahe.jpg (262.85 KiB) Viewed 242 times

Hbeta11_58_05Z_shift=0_clahe.jpg (151.19 KiB) Viewed 242 times

[thesmiths]

The H-alpha looks like it suffered a bit from the clouds. I never tried to reduce the aperture with H-beta but it seems like not a bad idea. I'm not sure if you need to go all the way down to f10. Maybe something like 60mm (which would be f7 in your case). 60mm at H-beta gives around 2 arcsec telescope resolution (probably a reasonable match to the seeing limit).

For my 720mm focal length refractor, I typically use an aperture stop of 72mm for Calcium, to bring it to f10. I could probably reduce this further to 60mm. I normally use the full aperture of 106mm for H-alpha, which gives a Rayleigh criterion of around 1.6 arcsec. Something like 80mm for H-beta and 60mm for Ca-K give comparable Rayleigh values.

[rsfoto]

Hi,

Absolutely stunning. Looks like taken with etalon. The orientation of the Sun looks a bit strange

[Montana]

Spectacular work how are you getting to see sunshine? it has rained every day of my holiday so far

Alexandra

[Alun_H]

Thank you all for the kind words.

Alexandra,I have the rig all set up in the observatory and any signs of breaks in the clouds and I am out there just for the off chance of capturing some images/scans.

Rainer,I thought I had rotated and flipped the images but have now realized I hadn't (was sat up til the early hours of the morning going through the data set) What had happened was I did a couple of inverted images and a Dopplergram of the Hbeta and flipped those to the correct orientation but forgot to do the ones above.

Douglas,I will be making up a couple of masks of different apertures,60,50 and another one of 40mm (my old one is getting beat up now) and experiment when looking in the UV/blue end of the spectrum. Just to show the difference cutting the 72 down to 40 I zoomed in to 100% of each disk and cropped a section of the center of the image,I had focused on the Hbeta line at full aperture of 72mm as best I could and then after having run off a couple of scans I put the 40mm mask in place,no alteration to focus and again recorded the scans.

11_02_35Z_shift=0_clahe-crop.jpg (152 KiB) Viewed 197 times

11_57_52Z_shift=0_clahe-crop.jpg (147.82 KiB) Viewed 197 times

Alun

[thesmiths]

That's quite a dramatic difference between 72mm and 40mm. I'm surprised, actually. And most people want bigger aperture?