caK shg and question about bandwidth option in Wah program

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highfnum
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caK shg and question about bandwidth option in Wah program

Post by highfnum » Sat Aug 22, 2015 9:48 am

I took this image 8-21-15
I used bandwidth 2 lines in Wah's program
Is using 2 lines better for caK, caH lines better than 1
since they are wide?

still thrilled I can get filaments in caK pics
cak2line.JPG
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Re: caK shg and question about bandwidth option in Wah progr

Post by highfnum » Sat Aug 22, 2015 9:49 am

colorized you can see proms at 10 and 9 o clock
cak2linec.JPG
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Re: caK shg and question about bandwidth option in Wah progr

Post by Merlin66 » Sat Aug 22, 2015 11:03 pm

With the SHG the final bandwidth comes down to the dispersion of the spectrograph (A/pixel) and the resolution (A) of the instrument.
Using the Nyquist sampling as a guide, you'll need at least two pixel to get resolution.
If you have 0.1A/pixel dispersion then a two pixel strip would give around 0.2 to 0.3A bandwidth resolution.
Always remember resolution is not the same as dispersion.
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Re: caK shg and question about bandwidth option in Wah progr

Post by highfnum » Sun Aug 23, 2015 1:47 pm

Thx

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Re: caK shg and question about bandwidth option in Wah progr

Post by highfnum » Sun Aug 23, 2015 10:26 pm

pic of my SHG rig
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Re: caK shg and question about bandwidth option in Wah progr

Post by Spectral Joe » Mon Aug 24, 2015 8:49 pm

Merlin66 wrote:With the SHG the final bandwidth comes down to the dispersion of the spectrograph (A/pixel) and the resolution (A) of the instrument.
Using the Nyquist sampling as a guide, you'll need at least two pixel to get resolution.
If you have 0.1A/pixel dispersion then a two pixel strip would give around 0.2 to 0.3A bandwidth resolution.
Always remember resolution is not the same as dispersion.
In most cases this works fine, but it gets more complicated if the collimator and camera have different focal lengths. For the average digital imager these days, with small pixels, binning 2 or 3 in the spectral direction may help. It will cause some astigmatism in the assembled image, though. The ultimate solution is to design the system so that the FWHM of the line profile at the detector is one pixel wide, but that usually involves long focal lengths.
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