Halpha spectroheliogram 25th Feb 2023

[Alun_H]

Chasing the gaps in the clouds I eventually recorded a few scans in the Hydrogen alpha wavelength earlier this afternoon (15:34 UT) with the 72ED and Sol'Ex but this time round I used the Hoya Pro ND16 filter at the front of the scope in place of the Herschel wedge. The image is a stack of three out of four scans,stacked in Autostakkert and processed in Astrosurface and Photoshop CS2. 16x sidereal on the CEM60 was used to force the Sun across the slit.

Alun

Ha-scan-20230225.jpg (293.33 KiB) Viewed 1538 times

Ha-scan-20230225_invert.jpg (264.35 KiB) Viewed 1538 times

[rsfoto]

Hi Alun,

Great positive H-alpha SHG.

¿ ND 16 ? that is a value of 4 stops. What is your exposure time then ?

May I know what filters apart from the ND filter do you have in the light path ?

[thesmiths]

What's your impression of the ND filter vs Herschel wedge? ND8 might be more appropriate for 72mm.

[rsfoto]

Hi,

What is the length of the travel of the focuser tube of the Evostar 72ED ?

Thanks

[Alun_H]

Thank you Rainer,the exposure time is set to around 6.77 milliseconds and I use the gain to alter the brightness (being careful not to push it so increasing noise) with the camera in 1x1 binning.
I don't have any other filters in the light path although at times I will put an Hydrogen Alpha 7nm filter on the nose piece of the Sol'Ex if I want to
cut out extraneous light leakage.

Douglas,I still prefer the Herschel wedge over the ND filter as I still believe the wedge produces a much sharper image. According to Christian Buil on his Sol'Ex web page their is the possibility of fringing with the ND8. http://www.astrosurf.com/solex/sol-ex-observation.html
I only used the filter due to my using the Herschel wedge on my other scope at the time.

Alun

[Alun_H]

Hi,

What is the length of the travel of the focuser tube of the Evostar 72ED ?

38mm

Alun

[rsfoto]

Hi,

What is the length of the travel of the focuser tube of the Evostar 72ED ?

38mm

Alun

Thanks

[marktownley]

Looks good to me Alun!

[Alun_H]

Thank you Mark!

Alun

[Montana]

Very very nice Alun

Alexandra

[DeepSolar64]

Alun,
These look really good. Like you used a normal etalon.

James

[Alun_H]

Thank you Alexandra and James for the kind comments.

Alun

[DeepSolar64]

Welcome.