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Exposure for Lumicon Ha Night Sky filter
#1
I am using a Lumicon Ha Night Sky filter. It is not a narrowband filter but instead a wide cut that blocks everything shorter than 630nm and only slightly attenuates anything longer. I have tried constructing a text file from the available filter data, but when I apply it within ST4 all the exposure calculator shows is 'error'. In the imaging I have done, exposure for this filter is a touch shorter than for my 'L' filter. What can I do?

thanks,

greg latiak

   
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#2
Post your file.
Clear skies,
Greg

SkyTools Developer
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#3
Greg,

Here is the dump of that Imaging system that contains the Lumicon Ha filter. We are away for a few days and I will have no access to email or regular internet services -- if that helps at all.

Thanks,

greg


Attached Files
.stx   VRC6 - Avalon.stx (Size: 17.67 KB / Downloads: 2)
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#4
Hello,

Your filter looks fine. If you are getting an Error in the filter list, when you close the dialog it will also warn you that the SNR for one or more of your filters could not be reached in a reasonable amount of time, and this is the same error. It means that the target object doesn't have enough signal out in the H-alpha and redward. Note that your camera detector QE also falls off after 700 nm.

So a bright or red star will have signal in this region, as well as HII regions and planetary nebulae with strong H-alpha lines. So pick your targets carefully. The target you tried is either too faint, or does not have a strong H-alpha emission line.
Clear skies,
Greg

SkyTools Developer
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#5
(2019-10-01, 01:14 AM)theskyhound Wrote: Hello,

Your filter looks fine. If you are getting an Error in the filter list, when you close the dialog it will also warn you that the SNR for one or more of your filters could not be reached in a reasonable amount of time, and this is the same error. It means that the target object doesn't have enough signal out in the H-alpha and redward. Note that  your camera detector QE also falls off after 700 nm.

So a bright or red star will have signal in this region, as well as HII regions and planetary nebulae with strong H-alpha lines. So pick your targets carefully. The target you tried is either too faint, or does not have a strong H-alpha emission line.
Ok. It was M16, by the way... 

g
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