Here’s a revised image of NGC 7293 Helix Nebula in Ha only. Further to my last SHO image, I captured more Ha on this target as this was the only way to increase detail whilst keeping noise at bay. The original Oiii data had a very high noise floor and Sii data had virtually no signal just mainly noise.
Total Ha data comprised of 343 x 180 sec dithered subs or about 17 hrs of acquisition.
The final result in Ha under my Bortle 8 City suburban light polluted skies had significantly improved from my original SHO version posted a week or so ago. This result was far more encouraging than the original showing more fine detail in the outer regions of the object.
I’ll probably add the original Oiii and Sii data to this image at some stage but I doubt it will improve the result on this Ha image other than the ability to produce a colour version.
Link to Astrobin for full resolution …..,
https://www.astrobin.com/1i1j2n/
Comments welcome
Thanks for looking
Martin
NGC 7293 Helix Nebula in Ha ( additional data )
NGC 7293 Helix Nebula in Ha ( additional data )
- Attachments
-
-
- NGC 7293 Helix Nebula additional Ha rev 2 Crop.jpeg (452.03 KiB) Viewed 3733 times
-
Re: NGC 7293 Helix Nebula in Ha ( additional data )
Plenty of signal and detail there, Martin! Good job 
two questions tho,
did you dither? I see some walking noise, streaks mottling on the image, specially on background, even if it's mono camera, I think dither helps too, it's noise after all.
I see on your previous image that you shot with 3min subs, what bandwith have your filters? Even in Bortle 8, like mine, I still rather shoot long exposures with my OSC and narrowband filter. (like 600s )
Regards,
Carles
two questions tho,
did you dither? I see some walking noise, streaks mottling on the image, specially on background, even if it's mono camera, I think dither helps too, it's noise after all.
I see on your previous image that you shot with 3min subs, what bandwith have your filters? Even in Bortle 8, like mine, I still rather shoot long exposures with my OSC and narrowband filter. (like 600s )
Regards,
Carles
Re: NGC 7293 Helix Nebula in Ha ( additional data )
Thanks Carles,
Yes I always get some mottle in the background when I image dim objects under B8 due to noise , probably not walking noise , more like noise due to the sensor read out due to Skyglow. I only dither a few pixels but should push a little harder with dithering to see if that reduces the effect.
I’ve been dithered since my DSLR and BYEOS days 6 years ago.
My filters are Antlia 3nm
I’ve tried 5 minute subs on dim objects and don't see any advantage, total integration is key , 3 min is a sort of sweet spot on the 2600MM camera at Gain 100 HGC at my focal length of 1050mm and ratio of f5.
If I shot 600 sec subs at my location I’d lose to many subs due to being in a flight path of Sydney Airport plus we suffer from poor atmospheric stability due to being in a basin between the mountains and the South Pacific Ocean.
Folk who live on the tablelands or western side of our mountain range (Great Dividing Range) have much more stable conditions.
Clear Skies
Martin
Yes I always get some mottle in the background when I image dim objects under B8 due to noise , probably not walking noise , more like noise due to the sensor read out due to Skyglow. I only dither a few pixels but should push a little harder with dithering to see if that reduces the effect.
I’ve been dithered since my DSLR and BYEOS days 6 years ago.
My filters are Antlia 3nm
I’ve tried 5 minute subs on dim objects and don't see any advantage, total integration is key , 3 min is a sort of sweet spot on the 2600MM camera at Gain 100 HGC at my focal length of 1050mm and ratio of f5.
If I shot 600 sec subs at my location I’d lose to many subs due to being in a flight path of Sydney Airport plus we suffer from poor atmospheric stability due to being in a basin between the mountains and the South Pacific Ocean.
Folk who live on the tablelands or western side of our mountain range (Great Dividing Range) have much more stable conditions.
Clear Skies
Martin