Request for SHG owners
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Request for SHG owners
Hello guys...
I need help from those you have a SHG :
My experiments with wide slit observations of prominences show that the 600 lpm grating gives the best definition of the images.
Could it be possible for those who have a 1200 or 600 lpmm grating to image the sun with it ? I would like to see what the proms will look like with such gratings ( even if the sun's disk details wont be visible).
Im interested to see the effect of the grating on the prominence image quality with a thin narrow slit in SHG mode.
Thank you in advance.
CHRIS
I need help from those you have a SHG :
My experiments with wide slit observations of prominences show that the 600 lpm grating gives the best definition of the images.
Could it be possible for those who have a 1200 or 600 lpmm grating to image the sun with it ? I would like to see what the proms will look like with such gratings ( even if the sun's disk details wont be visible).
Im interested to see the effect of the grating on the prominence image quality with a thin narrow slit in SHG mode.
Thank you in advance.
CHRIS
spectro-coronographe ,Bresser 127/1200 ; Bresser 102/1350 , ASI 178MM
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Re: Request for SHG owners
Thank you
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Re: Request for SHG owners
Hi, Chris:
Unfortunately I own only 2400 and 1800 g/mm gratings spectrographs, .Anyway, in my opinion, the higher is the grating resolution, the better could be the spectral image and spectroheliograms quality in digital SHG .
Cheers
Fulvio
Unfortunately I own only 2400 and 1800 g/mm gratings spectrographs, .Anyway, in my opinion, the higher is the grating resolution, the better could be the spectral image and spectroheliograms quality in digital SHG .
Cheers
Fulvio
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Re: Request for SHG owners
Hi Chris.
This thread shows my recent study of a prominence in H alpha and CaK using a spectroheliograph.
viewtopic.php?t=28630
For this particular imaging session, I was using a 1800 l/mm grating but, generally, I use a 2400 l/mm grating.
If you read through the thread you can see that I generated some dopplergrams and also examined spectra at various locations inside this prominence.
Some earlier (2015) work on a CaK prominence is presented here:
viewtopic.php?t=17102
Still learning my SHG craft at this point so the images were a little crude.
Cheers.
Peter
This thread shows my recent study of a prominence in H alpha and CaK using a spectroheliograph.
viewtopic.php?t=28630
For this particular imaging session, I was using a 1800 l/mm grating but, generally, I use a 2400 l/mm grating.
If you read through the thread you can see that I generated some dopplergrams and also examined spectra at various locations inside this prominence.
Some earlier (2015) work on a CaK prominence is presented here:
viewtopic.php?t=17102
Still learning my SHG craft at this point so the images were a little crude.
Cheers.
Peter
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Re: Request for SHG owners
@fulvio
Hmmmm..
I'm not conviced as my trials shows the opposite. The more dispersive grating and the more the image is squashed through anamorphosis. I tried with gratings from 600 to 2400 lpmm .Thats why i needed to check with people who are used to Digital SHG.
The more dispersive the grating is and the higher the spectral resolution will be but not necessarily the spatial resolution. Look at my posts with different gratings and you can see it.
I'll will try in SHG mode as soon as the sun comes back...
Hmmmm..
I'm not conviced as my trials shows the opposite. The more dispersive grating and the more the image is squashed through anamorphosis. I tried with gratings from 600 to 2400 lpmm .Thats why i needed to check with people who are used to Digital SHG.
The more dispersive the grating is and the higher the spectral resolution will be but not necessarily the spatial resolution. Look at my posts with different gratings and you can see it.
I'll will try in SHG mode as soon as the sun comes back...
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Re: Request for SHG owners
Chris, both me and C.Buil, that isn't surely a newby of spectroscopy and a precursor of digital SHG, use in general 2400 g/mm grating for SHG.The higher the spectral dispersion and resolution, the higher the definition of spectroheliograms.In my case , with my VHIRSS (for example) with a 2400 g/mm, H Alpha line is 60 pixel wide, and this permits to go deeper in the line with only one pixel image, or make the stacking of 60 one pixel images with good results.Anyway, if you are not convinced, could just give a try with two difefrent grating, a 600 and a 2400 g/mm.
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Re: Request for SHG owners
Hello,
I dont know ; i've been using the wide slit method for 24 years so far and i'm still experimenting
with my spectro and 2400tmm the H alpha line is 20 pixel wide but i'm not talking about spectral dispersion nor spectral resolution. I'm considering spatial resolution and so far my results are that with the 600lpmm the image of the prominence is better. That hold to the fact that i'm not using a thin band 1pixel wide to form an image but i use the whole H alpha line itself!! So the wider it is because of dispersion the more blurry my image will be. If selected a 1 pixel line that would be a completely different matter i guess but I have to try to see what the result will be. I'm not looking for the suns disk features for the moment but mainly the prominence image . I dont know If i express my thoughts acuretely as English isnt my first language
But soon I will see ...i mean as soon as i will understand how to use virtual dub to make the SHG .
I dont know ; i've been using the wide slit method for 24 years so far and i'm still experimenting
with my spectro and 2400tmm the H alpha line is 20 pixel wide but i'm not talking about spectral dispersion nor spectral resolution. I'm considering spatial resolution and so far my results are that with the 600lpmm the image of the prominence is better. That hold to the fact that i'm not using a thin band 1pixel wide to form an image but i use the whole H alpha line itself!! So the wider it is because of dispersion the more blurry my image will be. If selected a 1 pixel line that would be a completely different matter i guess but I have to try to see what the result will be. I'm not looking for the suns disk features for the moment but mainly the prominence image . I dont know If i express my thoughts acuretely as English isnt my first language
But soon I will see ...i mean as soon as i will understand how to use virtual dub to make the SHG .
spectro-coronographe ,Bresser 127/1200 ; Bresser 102/1350 , ASI 178MM
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Re: Request for SHG owners
weather has been a pain but i tried 1200 today
2400 lpmm opens emission line
this shot is with 50X300 scope in front and 50X300 camera scope
2400 lpmm opens emission line
this shot is with 50X300 scope in front and 50X300 camera scope
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Re: Request for SHG owners
this is 60X900 scope and 50X300 camera scope
it much thinner and brighter
it much thinner and brighter
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Re: Request for SHG owners
tried partial
of course clouds rolled in (grey streaks)
but edge is sharp
and surface mottling is there
of course clouds rolled in (grey streaks)
but edge is sharp
and surface mottling is there
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Re: Request for SHG owners
ok much better sky today
got a good half sun scan
10 micron slit
1200lpmm grating
60 f11 scope
nice
im happy
got a good half sun scan
10 micron slit
1200lpmm grating
60 f11 scope
nice
im happy
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Re: Request for SHG owners
very nice What fo you think about the prominence image ? can you scan with the 2400lpmm in the same session to compare?
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Re: Request for SHG owners
Here is proof that with the wide slit method the less dispersive grating gives the best image definition :
600 lines/mm gives that :
and the 1200 lines/mm
.
we can see the effect of anamorphosis : the image is squashed and the loss of resolution is due to the fact that each point of the image est dispersed and becomes a elipse or a line depending on how strong the dispersion.
Of course in the case of a SHG this doesnt apply as only a thin line of pixel is selected.
to be continued..
Chris
600 lines/mm gives that :
and the 1200 lines/mm
.
we can see the effect of anamorphosis : the image is squashed and the loss of resolution is due to the fact that each point of the image est dispersed and becomes a elipse or a line depending on how strong the dispersion.
Of course in the case of a SHG this doesnt apply as only a thin line of pixel is selected.
to be continued..
Chris
spectro-coronographe ,Bresser 127/1200 ; Bresser 102/1350 , ASI 178MM