First attempt at solar scan 21st Sept 22

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Alun_H
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First attempt at solar scan 21st Sept 22

Post by Alun_H »

Today I tried my first attempt at a solar scan in Ha using my Lhires III with 15um slit and 2400l/mm grating on a 120mm f/5 achromat stopped down to 60mm f/10. Because of the glass mirror slit I placed a Baader ERF over the objective limiting me to the Ha wavelength (have a neutral density filter on order) so as not to break the glass,used 3x rate on the handset of the CEM60 to force the scan (and beat the clouds). After using Solex reconstruction software I used Astrosurface to sharpen and rotate to correct orientation,still got plenty to learn ;)

Alun
10_46_02Z_shift=2_clahe_proc.jpg
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Lunt 50THa solar scope
Lunt CaK B12 module
SW Evostar 72ED for full disk imaging
Sol'Ex SHG
80mm f/7 achromat used with pressure tune module off the Lunt with Lunt 100mm ERF
Bresser 90 f/10 achromat used for CaK & white light imaging & PST mod with Lunt 100mm ERF
Coronado SM40 (pre Meade) and BF10 filter set + SMII 60 richview DS etalon
Skywatcher EQ6 Pro and Ioptron CEM60
Then there is all the night kit which is far too long a list to write up here! :lol:
More images on view on my Flickr page...https://www.flickr.com/photos/alun_h/
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Re: First attempt at solar scan 21st Sept 22

Post by Montana »

Wow!! well done :bow :bow

Alexandra


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Re: First attempt at solar scan 21st Sept 22

Post by thesmiths »

That looks very good, especially for a first attempt. Are the dark areas due to clouds? Was it not possible to scan faster because of the exposure time? I don't think you need both the ERF and an ND filter. Which reconstruction software did you use?


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Re: First attempt at solar scan 21st Sept 22

Post by Alun_H »

Thank you Alexandra,Douglas for the kind comments,also the SPOD totally unexpected :shock:

Douglas,I used the ERF for today's session but have the ND filter on order so as to replace it since I will want to image in the other wavelengths,I used an exposure time of 0.1873ms in Sharpcap with the QHY5III 178M (using ROI 3056x304) and just used the speed of x3 as a starting point which gave me an SER file of 3085 frames and 5 gig in size,but how fast is too fast before blurring/smudging of the detail in the images occurs? The darkening of the east limb is due to vignetting in the spectroscope the other areas are as you say clouds that drifted through. For reconstruction I used your software package,I did try Valerie's INTI but it kept crashing whereas yours is much more stable :bow2

Alun


Lunt 50THa solar scope
Lunt CaK B12 module
SW Evostar 72ED for full disk imaging
Sol'Ex SHG
80mm f/7 achromat used with pressure tune module off the Lunt with Lunt 100mm ERF
Bresser 90 f/10 achromat used for CaK & white light imaging & PST mod with Lunt 100mm ERF
Coronado SM40 (pre Meade) and BF10 filter set + SMII 60 richview DS etalon
Skywatcher EQ6 Pro and Ioptron CEM60
Then there is all the night kit which is far too long a list to write up here! :lol:
More images on view on my Flickr page...https://www.flickr.com/photos/alun_h/
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Re: First attempt at solar scan 21st Sept 22

Post by thesmiths »

In general, I would try to scan as fast as possible. Your exposure time is extremely short; is perhaps your gain too high? In general, I try to use gain close to zero. You might also try to use a narrower ROI (below 200). That will increase the FPS. The exposure time obviously needs to be faster than 1/FPS. Not many first attempts look that good!


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Re: First attempt at solar scan 21st Sept 22

Post by Alun_H »

Thank you,my gain was at a setting of 22 in Sharpcap so next attempt I will do as you suggest and use zero. I set the ROI to make allowance for the curvature of the Ha line,image below,which is typical of the Littrow design.

Alun
Capture.JPG
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Lunt 50THa solar scope
Lunt CaK B12 module
SW Evostar 72ED for full disk imaging
Sol'Ex SHG
80mm f/7 achromat used with pressure tune module off the Lunt with Lunt 100mm ERF
Bresser 90 f/10 achromat used for CaK & white light imaging & PST mod with Lunt 100mm ERF
Coronado SM40 (pre Meade) and BF10 filter set + SMII 60 richview DS etalon
Skywatcher EQ6 Pro and Ioptron CEM60
Then there is all the night kit which is far too long a list to write up here! :lol:
More images on view on my Flickr page...https://www.flickr.com/photos/alun_h/
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Re: First attempt at solar scan 21st Sept 22

Post by thesmiths »

Alun_H wrote: Wed Sep 21, 2022 7:44 pm I set the ROI to make allowance for the curvature of the Ha line, image below, which is typical of the Littrow design.
You could definitely make the ROI narrower -- that's really not that much curvature. Your camera is a little tilted with respect to the diffraction grating; if you correct that, you would need to also rotate the slit slightly.

The video is also quite a bit underexposed. The little line just underneath the H-alpha line should be just barely visible (then the exposure will be about right).

You might also consider attempting to clean the slit a bit. But I would consult the manufacturers instructions on how to do this.


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Re: First attempt at solar scan 21st Sept 22

Post by Alun_H »

Thank you for the tips,I can rotate the camera to sort the tilt,must have knocked it when I had to catch the spectroscope when it nearly crashed to the floor whilst setting up,thought I'd tightened the focuser lock screws enough Doh! The slit on the other hand cannot be adjusted in the Lhires,it is a square piece of glass with four slits engraved around its edges and it sits in a metal holder with no means of adjustment. As to cleaning I had a go at doing so following instructions from Shelyak but to no avail,I do have another plate that I have set up for my night observations of Be stars,once I know that the heat won't damage the glass I can swap over as these are not cheap at 188 quid a throw :(

Alun


Lunt 50THa solar scope
Lunt CaK B12 module
SW Evostar 72ED for full disk imaging
Sol'Ex SHG
80mm f/7 achromat used with pressure tune module off the Lunt with Lunt 100mm ERF
Bresser 90 f/10 achromat used for CaK & white light imaging & PST mod with Lunt 100mm ERF
Coronado SM40 (pre Meade) and BF10 filter set + SMII 60 richview DS etalon
Skywatcher EQ6 Pro and Ioptron CEM60
Then there is all the night kit which is far too long a list to write up here! :lol:
More images on view on my Flickr page...https://www.flickr.com/photos/alun_h/
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Re: First attempt at solar scan 21st Sept 22

Post by marktownley »

Very impressive indeed!


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Re: First attempt at solar scan 21st Sept 22

Post by Alun_H »

Thank you Mark.

Alun


Lunt 50THa solar scope
Lunt CaK B12 module
SW Evostar 72ED for full disk imaging
Sol'Ex SHG
80mm f/7 achromat used with pressure tune module off the Lunt with Lunt 100mm ERF
Bresser 90 f/10 achromat used for CaK & white light imaging & PST mod with Lunt 100mm ERF
Coronado SM40 (pre Meade) and BF10 filter set + SMII 60 richview DS etalon
Skywatcher EQ6 Pro and Ioptron CEM60
Then there is all the night kit which is far too long a list to write up here! :lol:
More images on view on my Flickr page...https://www.flickr.com/photos/alun_h/
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