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NGC281 - Pacman Nebula in Narrowband

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2 years 7 months ago #102874 by CarlightExpress
CarlightExpress created the topic: NGC281 - Pacman Nebula in Narrowband
Well I have to say this is my looooooooongest project to date, a total of 23.75 hours just for the hubble palette composition, so here it is

www.flickr.com/photos/30345959@N08/16302618672/

39x900S in 7nm HA (9.75 Hours)
30x900s in 7nm OIII (7.5 Hours)
26x900S in 7nm SII (6.5 Hours)
Each filter has 25 darks and 25 flat frames

Total exposure time 23.75 Hours

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The following user(s) said Thank You: johnomahony, Kinch, Al costello

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2 years 7 months ago #102878 by Kinch
Kinch replied the topic: NGC281 - Pacman Nebula in Narrowband
WOW Simon - looks great. I learned quite quickly when I started this hobby that long total exposure time was the only way to really bring out fine detail and go deep. Your patience in getting over 23 hours has been well rewarded.
Brendan.
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2 years 7 months ago #102879 by CarlightExpress
CarlightExpress replied the topic: NGC281 - Pacman Nebula in Narrowband
Thanks Brendan, I think I'll be stretching to 20 or 30 min subs for Narrowband in future, the mount is rock solid and has been thoroughly tested, an RMS of around 0.37 :)

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1 week 4 days ago #106720 by cbweb
cbweb replied the topic: NGC281 - Pacman Nebula in Narrowband
Hello,

This thread begun 2.5 yrs ago so hopefully there's still interest in it.

Not a great sky last pm with a very bright moon but I've begun a Pacman project hopefully I can add more data to over the next while. I got 10 of 10s same of 60s and 5 of 30m Ha subs so far the last infected by encroaching cloud. Subs are ok apart from some barrelling towards perimeters any got heads up on explanation of that or rectification?

I intend to apply some new processing techniques I've been acquiring lately from Josh Smith


But appreciate any tips on approaching your fine Pacman image there.

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1 week 3 days ago #106722 by cbweb
cbweb replied the topic: NGC281 - Pacman Nebula in Narrowband
Here's some initial processing of stacked 5 of 30min Ha

www.flickr.com/photos/colmbrazel/3567710...n/dateposted-public/

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1 week 3 days ago #106723 by CarlightExpress
CarlightExpress replied the topic: NGC281 - Pacman Nebula in Narrowband
Hey there

Well I must admit, the way I used to process in PhotoShop is not how I process now, I use PixInsight for all of my processing now, and the past few days, I have also been adopting the Stacking and Aligning with PixInsight too, so I have almost surely Ditched Maxim-DL, Nebulosity and Photoshop for my Astronomy image processing, here's a link to another Pacman Nebula of mine processed with PixInsight

www.stastrophotography.com/2016/11/10/ng...-palette-narrowband/

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1 week 3 days ago #106726 by cbweb
cbweb replied the topic: NGC281 - Pacman Nebula in Narrowband
Simon,

Great image interestingly on 8″ F4 Newtonian as well. About 12hrs of data do you mind me asking from what location you took them? Under arctic melt stratus cloud canopy for most of the time in Dublin that's a real challenge. I'm toying with an Autumn project on a narrowband target and hauling out my SCT 8" to gather data on a single target over a couple of months but not decided yet. I see the exposure lengths were 600s and wonder would subs of 1800s provide different result. I use an EQ8 only recently taming my setup to give 1800s I'm told for narrowband the longer and the more data the better. Regarding the tone mapping link I gave earlier I wonder does Pixinsight allow for star removal prior to processing the nebula ...but... lots to think about from your image there thanks.

Colm

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1 week 2 days ago #106727 by CarlightExpress
CarlightExpress replied the topic: NGC281 - Pacman Nebula in Narrowband
Hey Colm

I didn't get a chance to look at that link yet, on your SCT you are going to need longer exposures as it is an F10 right?

I went from an F7.5 to an F4, which means my 10 min expsoure on my F4 is the same as a 35min exposure on F7.5, hence why I am abale to get a much more level of detail within a shorter exposure time, with F10 it is going to be a struggle, especially at a higher focal length too, this is one of the issues I had when I had my Ritchey Chretien, it was an F8, however the Focal length of 1600mm gave me some trouble, I had to increase the exposure time, and could never get the stars as pinpoint. Although I have learnt a hell of a lot more about guiding now :D

With longer focal length you yield a bigger resolution, but longer focal length also means longer exposure times, especially for narrowband.

All of my recent images post 2014 have been done in the UK, past couple of years from my home built observatory

Regards
Simon

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1 week 2 days ago #106728 by cbweb
cbweb replied the topic: NGC281 - Pacman Nebula in Narrowband
Simon,

You'll be surprised its an Omni XLT Celestron refractor f5 with 3 matchsticks to stiffen focuser. Pacman above taken with it. Logic don't need a triplet for chromatic aberration for narrowbandpass but could do with a field flattener still looking at alternatives. I did make the mistake of going initially for long FL SCT 11" the weight ruining the Neq6 mount needed a Vimech wedge. Bloated stars are a problem along with too narrow FOV should make SCT long FL a nono for deepsky learned the hard way. No observatory but permanent pier.Recently got polemaster camera has made huge difference to alignment PA as I need to setup new most sessions. Re exposure lengths probably need to experiment more for local optimisation your 10m subs perhaps a better choice than my 1800s www.qdigital-astro.com/calculator

Clear skies,

Colm

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