The Heart Nebula Double Stacking Project

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mAnKiNd
Posts: 177
Joined: Sun Jun 11, 2017 4:55 pm
Location: Long Island, NY
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The Heart Nebula Double Stacking Project

Post by mAnKiNd » Sun Sep 16, 2018 4:47 pm

I'd like to share the ongoing results from a project that I've just embarked on from my Bortle 8/9 backyard. My goal is to obtain short (i.e. 15minute) fully calibrated (flats and darks 60 each) live stacks every night and then to double stack them in DSS as if they were single long-exposure lights. I aim to construct and HO (one-shot hydrogen/oxygen) RGB image of the Heart Nebula using this approach.

So far, over the past two nights, I managed to stack 496 frames for HO, in live stack batches of 30 frames each, yielding a total of 16 stacks. Each stack of 30 frames included exposures of 30 seconds, with a gain of 230 and an offset of 100. A peculiar feature in sharpcap when enabling auto-save every 15 minutes was that it stacked a 31st frame rendering a stack time of 15 minutes 30s.

I used FWHM filter at 5.30 and auto-brightness filter to reject outlier frames due to bad tracking or clouds and the stacking algorithm was set at sigma clipping with parameters adjusted to reject no more than 0.1% pixels in each frame.

The 16 stacks were then double stacked in DSS using median kappa sigma clipping with a threshold set to 3 and 30 iterations. I then used Photoshop to stretch and do some basic processing.

The canon lens was stepped down to f/5.45 using front-loaded step down filter rings with an effective front aperture of 55mm instead of the native 75mm.

So far I really like what I'm getting, here is the link to the (unpublished work-in-progress) image:

https://www.astrobin.com/367007/C/?nc=user

I've also attached a compressed jpg for quick viewing:
IMG-20180916-WA0000.jpg
IMG-20180916-WA0000.jpg (338.4 KiB) Viewed 252 times
Will post updates as I add more data for HO and RGB

Cheer
Minos
Last edited by mAnKiNd on Sun Sep 16, 2018 5:39 pm, edited 4 times in total.
Celestron AVX & SW Az-GTi (EQ)
SW Esprit 80 & 150PL, Canon 300mm f4 (non-IS)
ASI1600MM PRO
EFWmini - HOLRGB
ASI120MM mini for guiding
SC CDC PHD2 DSS PI PS

https://www.astrobin.com/users/minoSpace/

mAnKiNd
Posts: 177
Joined: Sun Jun 11, 2017 4:55 pm
Location: Long Island, NY
Contact:

Re: The Heart Nebula Project

Post by mAnKiNd » Sun Sep 16, 2018 4:48 pm

Here's a picture of my backyard and setup so you get an idea of what I'm working with:
Attachments
09_15_18_11_52_30_IMG_20180914_231539.jpg
09_15_18_11_52_30_IMG_20180914_231539.jpg (106.95 KiB) Viewed 254 times
09_15_18_11_52_31_IMG_20180915_005323.jpg
09_15_18_11_52_31_IMG_20180915_005323.jpg (124.58 KiB) Viewed 254 times
09_15_18_11_52_30_IMG_20180914_231657.jpg
09_15_18_11_52_30_IMG_20180914_231657.jpg (153.93 KiB) Viewed 254 times
Celestron AVX & SW Az-GTi (EQ)
SW Esprit 80 & 150PL, Canon 300mm f4 (non-IS)
ASI1600MM PRO
EFWmini - HOLRGB
ASI120MM mini for guiding
SC CDC PHD2 DSS PI PS

https://www.astrobin.com/users/minoSpace/

mAnKiNd
Posts: 177
Joined: Sun Jun 11, 2017 4:55 pm
Location: Long Island, NY
Contact:

Re: The Heart Nebula Project

Post by mAnKiNd » Sun Sep 16, 2018 4:51 pm

Single example HO Live Stack details:

[ZWO ASI1600MM Pro]
Pan=0
Tilt=0
Output Format=FITS files (*.fits)
Binning=1
Capture Area=4656x3520
Colour Space=MONO16
Hardware Binning=Off
High Speed Mode=Off
Turbo USB=100(Auto)
Flip=None
Frame Rate Limit=Maximum
Gain=230
Exposure=30
Timestamp Frames=Off
Brightness=100
Temperature=-15
Cooler Power=58
Target Temperature=-15
Cooler=On
Auto Exp Max Gain=300
Auto Exp Max Exp M S=30000
Auto Exp Target Brightness=100
Pattern Adjust=0
Apply Flat=C:\Users\dj_mi\OneDrive\minoSpace\SharpCap Captures\HEART\2018-09-15\flats\20_56_31.fits
Subtract Dark=C:\Users\dj_mi\OneDrive\minoSpace\SharpCap Captures\BUBBLE\2018-09-14\darks\dark_60_frames_-15.0C_2018-09-15T01_54_23.tif
#Black Point
Display Black Point=0.064453125
#MidTone Point
Display MidTone Point=0.213368151885418
#White Point
Display White Point=0.998046875
ZWO FilterWheel (1)=HO
TimeStamp=2018-09-16T04:51:13.1067038Z
SharpCapVersion=3.2.5756.0
TotalExposure(s)=930
StackedFrames=31

FITS LIBERATOR CROP.jpg
FITS LIBERATOR CROP.jpg (237.64 KiB) Viewed 244 times
Last edited by mAnKiNd on Sun Sep 16, 2018 5:24 pm, edited 3 times in total.
Celestron AVX & SW Az-GTi (EQ)
SW Esprit 80 & 150PL, Canon 300mm f4 (non-IS)
ASI1600MM PRO
EFWmini - HOLRGB
ASI120MM mini for guiding
SC CDC PHD2 DSS PI PS

https://www.astrobin.com/users/minoSpace/

mAnKiNd
Posts: 177
Joined: Sun Jun 11, 2017 4:55 pm
Location: Long Island, NY
Contact:

Re: The Heart Nebula Double Stacking Project

Post by mAnKiNd » Sun Sep 16, 2018 5:05 pm

Forgot to mention that I used both the smart histogram tool followed by manual fine-tuning and visual confirmation to get the histogram I thought was best for the stack. I forgot to save an individual frame to share its FITS Liberator image here, I'll do that on the next run.

I wanted to also add that I chose to go for high gain of 230 to improve (lessen) quantization error. Any loss in DR would be recovered when doublestacking many stacks.

Furthermore, each stack upon completion and auto-save and reset, was manually triggered to dither in PHD2 by 15 pixels on the imaging scale before starting a new stack. This was to benefit the stacking algorithm in DSS. Individual frames going into the 15 minute live stack were not dithered, but guided.

Cheers
Minos
Celestron AVX & SW Az-GTi (EQ)
SW Esprit 80 & 150PL, Canon 300mm f4 (non-IS)
ASI1600MM PRO
EFWmini - HOLRGB
ASI120MM mini for guiding
SC CDC PHD2 DSS PI PS

https://www.astrobin.com/users/minoSpace/

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oopfan
Posts: 370
Joined: Sat Jul 08, 2017 2:37 pm
Location: New York
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Re: The Heart Nebula Double Stacking Project

Post by oopfan » Sun Sep 16, 2018 5:19 pm

Excellent work, Minos! It is amazing what can be done in light-polluted environments. I can't wait for the colorized version! Also, what's great about narrowband imaging is that it can be done while the Moon is up. We don't get that many clear nights in the NYC area, so narrowband is a great addition.

Brian

User avatar
turfpit
Posts: 486
Joined: Mon Feb 13, 2017 8:13 pm
Location: UK
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Re: The Heart Nebula Double Stacking Project

Post by turfpit » Sun Sep 16, 2018 5:52 pm

Minos

Nice shape on the histogram and good figures for the min, max image statistics in FITS Liberator.

I think the front lawn needs a trim though :lol:

Dave

mAnKiNd
Posts: 177
Joined: Sun Jun 11, 2017 4:55 pm
Location: Long Island, NY
Contact:

Re: The Heart Nebula Double Stacking Project

Post by mAnKiNd » Sun Sep 16, 2018 6:31 pm

Thanks guys!

Brian - Yes, narrowband is a must for detail in such LP! RGB will be washed out in comparison. Still though, the HO data will serve as the detail in the Luminance :)

Dave - Yes, I too am pleased with the data distribution :) I wouldn't really want to disrupt the critter ecosystem running rampant in the plantlife and lawn in front of my backyard, they keep me company at night - haha, no really, the apartment complex is responsible for managing that, they also manage to turn the sprinklers on at 2am, so that's my curfew!

I've just restacked the 16 stacks using SC Live Stack again using folder monitor and the same settings as above. You can see the dithering was aggressive and causes you to sacrifice some fov and also causes the bumpy tail on the black end of the histogram. I'm processing it to the same level as the DSS stack to compare them.
folder monitor screenshot.png
folder monitor screenshot.png (702.78 KiB) Viewed 234 times
Celestron AVX & SW Az-GTi (EQ)
SW Esprit 80 & 150PL, Canon 300mm f4 (non-IS)
ASI1600MM PRO
EFWmini - HOLRGB
ASI120MM mini for guiding
SC CDC PHD2 DSS PI PS

https://www.astrobin.com/users/minoSpace/

mAnKiNd
Posts: 177
Joined: Sun Jun 11, 2017 4:55 pm
Location: Long Island, NY
Contact:

Re: The Heart Nebula Double Stacking Project

Post by mAnKiNd » Sun Sep 16, 2018 6:44 pm

Well, there are certainly visible differences with the DSS stack, can't say I prefer one or the other yet, need to have a closer look.
Heart Nebula_09_16_2018T14_15_11_Stack_16bits_16frames_191s__Light_.jpg
Heart Nebula_09_16_2018T14_15_11_Stack_16bits_16frames_191s__Light_.jpg (551.89 KiB) Viewed 231 times

For an A/B comparison, open these two links in new tabs:
DSS: https://www.astrobin.com/full/367007/D/
SC: https://www.astrobin.com/full/367007/E/?nc=minoSpace
Celestron AVX & SW Az-GTi (EQ)
SW Esprit 80 & 150PL, Canon 300mm f4 (non-IS)
ASI1600MM PRO
EFWmini - HOLRGB
ASI120MM mini for guiding
SC CDC PHD2 DSS PI PS

https://www.astrobin.com/users/minoSpace/

mAnKiNd
Posts: 177
Joined: Sun Jun 11, 2017 4:55 pm
Location: Long Island, NY
Contact:

Re: The Heart Nebula Double Stacking Project

Post by mAnKiNd » Sun Sep 16, 2018 6:47 pm

same SC double stack as posted above, but one more curve stretch.
Heart Nebula_09_16_2018T14_15_11_Stack_16bits_16frames_191s__Light_curve.jpg
Heart Nebula_09_16_2018T14_15_11_Stack_16bits_16frames_191s__Light_curve.jpg (652.73 KiB) Viewed 226 times

https://www.astrobin.com/full/367007/F/?nc=minoSpace
Celestron AVX & SW Az-GTi (EQ)
SW Esprit 80 & 150PL, Canon 300mm f4 (non-IS)
ASI1600MM PRO
EFWmini - HOLRGB
ASI120MM mini for guiding
SC CDC PHD2 DSS PI PS

https://www.astrobin.com/users/minoSpace/

mAnKiNd
Posts: 177
Joined: Sun Jun 11, 2017 4:55 pm
Location: Long Island, NY
Contact:

Re: The Heart Nebula Double Stacking Project

Post by mAnKiNd » Sun Sep 16, 2018 6:53 pm

and one more curve stretch for the DSS stack.
median sigma curve.jpg
median sigma curve.jpg (651.28 KiB) Viewed 224 times

https://www.astrobin.com/full/367007/G/?nc=minoSpace
Celestron AVX & SW Az-GTi (EQ)
SW Esprit 80 & 150PL, Canon 300mm f4 (non-IS)
ASI1600MM PRO
EFWmini - HOLRGB
ASI120MM mini for guiding
SC CDC PHD2 DSS PI PS

https://www.astrobin.com/users/minoSpace/

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