NGC 7380 - Wizard Nebula

[SyedT]

I find the Wizard Nebula fascinating and have wanted to capture it for a long time. The shape is so well-defined, and the surrounding Ha nebulosity adds further to its eeriness. I was quite surprised by the amount of detail provided by the SII. As always, I welcome any advice from the experts on the forum! I tried to lay off the noise reduction to avoid losing detail, hopefully it worked. Some of the frames were taken under not so ideal skies, so I feel adding more integration time would help with noise reduction etc. For now, 26.5 hours is more than enough!

Equipment:

Atik 490EX
Atik EFW2
Chroma NB filters
Primaluce Lab Esatto 3” Robotic Focuser
Takahashi FSQ85-EDX
Takahashi EDP Flattener 1.01x
Starlight Xpress Lodestar X2 + Tecnosky 70 mm guidescope
Avalon M-Uno
QHYCCD PoleMaster
Pegasus Ultimate Powerbox
Intel NUC Mini PC

Acquisition:

Ha: 77 x 300s = 385 min = 6h25min
OIII: 120 x 300s = 600 min = 10h
SII: 120 x 300s = 600 min = 10h

Processed in AstroPixelProcessor & Pixinsight

Bortle 5/6 skies

[Uranium235]

Looks good, but to kill that noise - I would personally opt for subs which are much longer than 300s.

You are using a CCD, so your exposure time is only limited by the brightess of your target, or the local LP - neither of which should come into play in narrowband. So ramp it up to 900s and replace some of the data captured under "less than ideal" conditions, if you keep bad data in the mix it can sometimes bring down the end result... a case of quality over quantity perhaps, but ideally its quality and quantity.  It will take a while since you may need to manually inspect all of your subs and toss "bad" ones into a separate folder.

If you can push it further than 900s, do it. Higher risks yes, but the rewards are worth it   (but 900s is a good benchmark to start off with).

[SyedT]

13 minutes ago, Uranium235 said:

Looks good, but to kill that noise - I would personally opt for subs which are much longer than 300s.

You are using a CCD, so your exposure time is only limited by the brightess of your target, or the local LP - neither of which should come into play in narrowband. So ramp it up to 900s and replace some of the data captured under "less than ideal" conditions, if you keep bad data in the mix it can sometimes bring down the end result... a case of quality over quantity perhaps, but ideally its quality and quantity.  It will take a while since you may need to manually inspect all of your subs and toss "bad" ones into a separate folder.

If you can push it further than 900s, do it. Higher risks yes, but the rewards are worth it   (but 900s is a good benchmark to start off with).

Thanks for the feedback! I was aiming for 600 second subs as a minimum since that's what I tend to go for in NB, but a combination of poor seeing and therefore bad guiding meant I couldn't do that and had to settle for 300 seconds. I guess the next step would be to take a bunch of longer subs and add them on. 

[Uranium235]

10 minutes ago, SyedT said:

Thanks for the feedback! I was aiming for 600 second subs as a minimum since that's what I tend to go for in NB, but a combination of poor seeing and therefore bad guiding meant I couldn't do that and had to settle for 300 seconds. I guess the next step would be to take a bunch of longer subs and add them on. 

Ahhh yes, guiding can also limit your sub length. As well as having one of those nights where the sky can be very on/off. Next time its a perfect sky, just get out there and hammer it with Ha as that will carry most of your luminance and contrast 

[SyedT]

8 hours ago, Uranium235 said:

Ahhh yes, guiding can also limit your sub length. As well as having one of those nights where the sky can be very on/off. Next time its a perfect sky, just get out there and hammer it with Ha as that will carry most of your luminance and contrast 

Guiding has been a frustration at times. The Avalon M-Uno is great in terms of requiring fewer counterweights/no meridian flip/no backlash etc, but that comes at the cost of being more susceptible to wind and even the slightest imbalance. I've been running 300s subs in luminance for M31 and that's lifting the histogram easily off to the right. For my NB subs, I'm just about getting the histogram off the left edge to avoid clipping, but 600s subs as a minimum would be ideal, particularly as my filters are 3 nm.

Annoyingly enough, pretty much all of last night's subs came through fine (M31 Lum 300s) despite it being pretty windy!

Edited September 26, 2020 by SyedT