Spectroheliograms from 17th & 18th March 2023

[Alun_H]

Spent a bit of time tinkering with the Sol'Ex in regards the focus of the collimator lens on the slit. Instead of the setting of infinity focus on the camera/lens assembly I removed the slit housing along with the collimator lens tube as a unit and using the trusted method with a finder scope (in this case a 6x30) focused to infinity I kept adjusting until I got focus as sharp as possible,locked the assembly then re-inserted back into the Sol'Ex casing. Managed to get to test the focusing on the 17th when cloud cover cleared for a while in the afternoon so ran off a few scans in CaK (scope reduced to 50mm),Hbeta and Halpha.

CaK-14_09UT-20230317_clahe.jpg (125.74 KiB) Viewed 1407 times

Hbeta-14_21UT-20230317-clahe.jpg (135.22 KiB) Viewed 1407 times

Ha-13_51UT_20230317_clahe.jpg (131.52 KiB) Viewed 1407 times

Then on the afternoon of the 18th I managed a scan in the Halpha

Ha-20230318_1411UT_clahe.jpg (184.26 KiB) Viewed 1407 times

All single scans so only processing (mainly on data of the 17th) is adjustment to brightness levels,as to orientation I left the CaK and Hbeta as they came from the SHG but both Halpha images are north to the top. 16x sidereal speed used on CEM60 to force the scans using Sharpcap to record the 16 bit SER files.

Alun

[rsfoto]

Hi,

Beautiful SHG's

[Alun_H]

Thank you Rainer.

I forgot to add this little gif of one of the scans I recorded in the Halpha wavelength on the 17th at the time a flare (or some activity) was in progress
around sunspot AR3256. Scan is cropped to the specific part of the scan area to cut down file size. Cloud drifted through whilst recording so this scan
wasn't used for a full reconstruction.

15_14_04Z_F160-179.gif (888.47 KiB) Viewed 1395 times

15_14_04Z_shift=0_clahe cropped.png (158.28 KiB) Viewed 1395 times

Alun

[rsfoto]

Hi Alun,

Excellent. I am slowly but steadily getting closer to better results.

I am more interested in CaK and other lines then H-alpha and there is were I am playing now.

[thesmiths]

Alun, these are all really good. In particular, the CaK and the 2nd H-alpha look very sharp.

With regards to focusing the collimator "using the trusted method ", I didn't think there was really any other way to do it? Or do you mean you just used a purely visual method instead of doing it with the aid of a camera? Collimator focus is, I think, the part that is most often off. The Solex does not allow collimator focus during use -- which may actually be an advantage because I think many people would adjust this and get so far off track they would never find their way back.

Can you tell me what the exposure and gain were for the three wavelengths? I'm curious how much attenuation you get with the Herschel wedge. As you may know, I use my own quartz slits that require only a UV/IR filter so I typically operate near 1ms and zero gain.

[Alun_H]

Thank you Rainer,Douglas

The Sol'Ex collimator and slit are focused by firstly focusing the camera/lens assembly to infinity,replacing them back into the Sol'Ex body then watching the live feed on screen the focus of the slit collimator is adjusted by sliding the block supporting the slit,which I don't find that easy being plastic,the block sticks to the support plate underneath it so no fine adjustment as such and I end up getting frustrated with it. So I took the block and collimator tube off as a unit and holding the 6x30 finder to the collimator lens I fine tuned the focus and locked it down,which I should have done right from the start.

I'll collect up the camera setting files and put them here when I get back into my observatory in the morning. I am beginning to think though that the wedge I have (Scopium) may not be the ideal model to use as it has an open bottom With the 10um slit I know I am using far more exposure time and much more gain than you are. Off top of my head the exposures are in the 6.75 ms with a gain of between 6-9 (Sharpcap settings) but as I say I'll clarify these settings with the log files later.

Just out of curiosity,would be at all possible that one of your quartz slits could be installed in the Sol'Ex in place of the glass slit?

Alun

[thesmiths]

Just out of curiosity, would be at all possible that one of your quartz slits could be installed in the Sol'Ex in place of the glass slit?

Yes, I think it's possible. I know of at least one person, Brian Martin in Canada, who has done this:

https://groups.io/g/Solex-English/message/346

https://groups.io/g/Solex-English/message/404

My newest mounting method is just a 1.25-inch filter cell. So you just need to make a new 3D printed piece that will accept this thread. (Brian used an earlier version which was just the quartz slit mounted onto a 25.4mm copper disk.) Perpendicular mounting is fine (no need for the tilt that the Shelyak slit has, which is really meant for night-time guiding).

I imagine that the copper disk and filter cell are probably enough of a heat sink and radiator. So I'm guessing the filter cell could just be screwed directly into a 3D printed plastic part. You might want to make sure that direct focused sunlight does not land on any plastic part (by shielding with some reflective foil around the filter cell, just in case).

I would recommend being able to rotate the slit slightly in the 3D printed part to orient the slit correctly with respect to the grating. Rotating the copper disk inside the filter cell is not so easy.

[Montana]

These are fabulous images Alun, are these single frame images or do you stack a couple like Douglas?

Alexandra

[Alun_H]

Yes, I think it's possible. I know of at least one person, Brian Martin in Canada, who has done this:

Thank you for the links Douglas and confirming that your slit can fit,I will look into getting a suitable attachment sorted,I don't have a 3D printer but
can no doubt come up with something,as soon as I have something I will contact you via PM.

Alun

[Alun_H]

These are fabulous images Alun, are these single frame images or do you stack a couple like Douglas?

Thank you Alexandra,these are all single frames with minimal processing (brightness levels).

Alun

[Alun_H]

Can you tell me what the exposure and gain were for the three wavelengths? I'm curious how much attenuation you get with the Herschel wedge. As you may know, I use my own quartz slits that require only a UV/IR filter so I typically operate near 1ms and zero gain.

Checking out the log files for the exposures and gain setting they are much higher than I'd estimated,especially in the gain settings.

Capture software is Sharpcap,camera set to 16 bit 1x1 binning,,

Cak ...... exposure time 9.3157ms gain....24
Hbeta....exposure time 11.3431ms gain....7
Halpha...exposure time 5.8840ms gain...10

Definitely going to sort out the attachment for one of your quartz slits Douglas

Alun

[thesmiths]

Hi Alun, that doesn't seem like very high gain. Isn't the max 510? The exposure is certainly not short, so definitely limits the fps. I like to target 300 fps, which means the exposure has to be 3ms or faster. I'm saving a quartz slit for you

[Alun_H]

I'm saving a quartz slit for you

Thank you Douglas,PM sent

Alun