IC 1805 - The Heart Nebula in SHO - 11.5 Hours
Date: November 13, 2021
Cosgrove’s Cosmos Catalog ➤#0087
IC 1805 - The Heart Nebula. (click to image for full resolution via Astrobin.com).
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About the Target
IC 1805 is also known as SH2-190 and, more commonly, the Heart Nebula. It is located 7500 light-years away in the constellation of Cassiopeia. First discovered by William Herschel in 1787, the Heart Nebula is a region of glowing gas and dark dust lanes.
The gas and dust are ionized and excited by a clump of large bright stars located in the nebula's center, in a region known as Melottle 15, sometimes called the "Heart of the Heart." This cluster of stars contains many stars that are fainter and smaller than our sun but also include a few large stars that are 50 times the mass of our sun. It is these stars that create the glow in the nebula.
The Annotated Image
The annotated image was created using the ImageSolver and AnnotateImage scripts in Pixinsight. (Click to enlarge)
The Location in the Sky
This IAU/Sky & Telescope Constellation Chart shows the location of the IC 1805, indicated by the yellow arrow.
About the Project
November can be an interesting month in Western New York when it comes to Astrophotography. We are well into late fall, the leaves are coming down, and the nights are getting cold with the first frosts of the season. The cold weather is often cloudy and stormy. Any observing nights are precious because, in late November, the clouds move in, and the opportunities for astrophotography become rare until spring.
But if you do get some clear nights - they can be magical. Darkness descends at 5 pm and stays until 7 am. Excluding the twilight period, this means you can get almost 12 hours of capture accomplished in one evening this time of year! Added to that is that in the early evening, some of the best parts of the sky from summer are still available, while late-night introduces some of the gems of the winter sky. So if you get a clear night this time of year - you go for it!
Recently I spent a month down in North Carolina - which is supposed to have much better weather than in Rochester, New York. Unfortunately, it did not work out that way. We only had a single night that was clear and with no moon - and this resulted in my wide-field image of IC 1396, The Elephants Trunk Nebula, which can be seen HERE.
Amazing Weather for a Change!
So coming back from North Carolina, I wondered what the next lunar cycle would look like here. Low and behold, we ended up hitting the jackpot! We had three and a half clear nights in a row with no moon! Friday, November 5 through the 8th were beautifully clear!
Think about that for a minute. Four nights, with twelve hours of potential capture, and three scopes being run in parallel. That’s 4*12*3=144 hours of possible capture! WOW.
Now realistically, I could never get so much integrated time. Some of that time is spent doing focus runs and scope centering operations and taking flat fields for each unique camera angle used. Also, you may remember that I have tree lines hemming me in. For most targets, I cannot get anything longer than 3-4 hours because I can only see them once they have risen above the tree line on the east side of my property and until they set into the tree line on the west side of my property. So each night, I select targets, shoot them while I can, and then wait for the next target to rise. This sometimes provides periods where no target is available to shoot.
In the end, I was able to shoot for all of that time, and on the final night, I was able to go until 3 am before the clouds came in and shut me down. I ended up capturing subs for a total of nine targets during that time.
IC 1805 was the first one that I processed.
As it turns out, I have shot a portion of this target before. The Heart nebula includes the Fish Head Nebula, IC 1795, and can be seen HERE. This image was shot with the WO132 platform, and the focal length is too long to fit in anything other than the Fish Head. But this time around, I had the FRA400 platform up and running and could now fit the entire Heart Nebula into the field of view.
A Personal Processing Milestone
This image also marks another milestone of sorts. When I first started doing astrophotography, I used Photoshop to process my images. I was happy with this as I have been a long-time Photoshop user, and I found this to be very natural. However, I learned that Pixinsight was a much more suitable tool for this kind of image processing. You could do one set of operations that makes sense in the linear domain and then move to the nonlinear domain to do what makes sense there.
There is a huge learning curve with Pixinsight, so at first, I did about 20% of my processing in Pisinsight and 80% in Photoshop. Over time this shifted to 80% done in Pixinsight and 20% in Photoshop. This was the first image where 100% of the image processing was done in PI and none in Photoshop. The only thing I did in Photoshop was to add my watermarks and export them as jpegs. It's been a long road, but I guess my conversion to PI is complete!
IC 1805 Processing Log
A Special Note: I have to give a special thanks to an outstanding local Astrophotographer, Gary Opitz. Gary shot this same target over a year ago with a wide field rig in SHO and at that time he generously shared with me many of the techniques he used for processing that image. Since I was now working on the same target, I followed many of those tips here and this was a great help in achieving the result I did. Thanks, Gary - you are a master at processing SHO images! (Gary’s Astriobin Account) (Gary’s version of 1C 1805)
Now, back to our regularly scheduled program.
1. Blinking the Images
All lights and cal frames were blinked
some minor gradients on the S2 images were seen - but very minor.
No subs were eliminated.
Cal frames all looked good.
300-second darks were taken from my recent IC1396 project
2. WBPP v2.2 was loaded with all subs and cal frames
Setup cosmetic correction
Setup for drizzle integration
Because I was doing drizzle integration, I choose to have the script also do preliminary integration, but I set the sigma level low to 3.3 std dev, and the high to 2.5. I also checked large-scale rejection and set that up for both high and low at 2x2.
Set up output pedestal to 50. (Note I took the screen snap below before I remember to add the pedestal image)
Note on Flat images: Usually I shoot flats every night of a project because moving the scope each night to put it away means that I might bump dust motes into a new position. Then I would apply those flats to the lights taken the same night. But because of the complexity of this capture sequence with 9 targets on three scopes for 4 nights - I took the risk of not doing that this time. It seemed to work out OK.
Here is my WBPP setup. Note that I did use a pedistal image of 50 that is not shown in this screen snap.
Here is the summary of my lights for this project.
3. DrizzelIntegration
Run with defaults on registered images for Ha, O3, & S2 images,
4. DynamicCrop - all master images were cropped in a consistent fashion to exclude ragged edges.
5. Run DBE
Run DBE on all images. Set up the samples with a radius of 150, 10 per row. Remove boxes from nebula - save. Use on Ha. Then Tweak and use on O3 and S2.
DBE Sampling Setup (click to enlarge)
6.0 Prep for Deconvolution
Object Masks created for each layer.
A copy made of the Linear image. Use STF->HT methods of creating nonlinear image
HT was used to adjust the mask so that the background sky was black, and most Nebula areas were white. Convolution run on mask 2X, with std dev = 2.
Create local Support Image
These are basically star maps of the biggest and brightest stars. Since these are usually saturated and clipped, they never have normal point spread functions, so they don’t fit the deconvolution model and it does bad things to them.
This was created using the Ha image and used for all. I used Starmap with 6 layers and every else set to default for this.
Final image was boosted a bit using HT
Psf files created- These are point spread function files. I created the using the PSImage Script. Piece of cake!
7. Run Deconvolution
Setup several preview areas to test on each image
Apply the object mask
Set the deconvolution tool to use the right psf and local support maps
For each layer - explore what global dark value gives the best response without dark rings.
Ha: 0.01, 40 interactions
O3: 0.01, 20 interactions
S2: 0.01, 20 interactions
8. Linear noise reduction
Create luminance mask by making a copy of the image and going nonlinear with STF->HT process
Apply mask - invert the mask.
Apply MLT with the following parameters shown below
Test on preview and apply to each image.
9. Go Nonlinear and Combine Images
Now I was ready to go nonlinear. For each image:
Used STF->HT method. Adjusted the HT to adjust zero point on the left side of the histogram and then move the mid-tone slider to brighten.
Adjust each with HT to look visually similar.
Nonlinear Ha, O3, and S2 Images (Click to enlarge)
10. Create a Color SHO Image.
Use ChannelCombinaton tool to create the initial SHO image. This is image is very green - now remove the excess green
SCNR with Green Channel
Now the problem is the magenta stars in the rea outside the nebula. Remove this by making a mask
use ColorMask script to select magenta - set blur layers to 1.
Now edit out the shape of the nebula and its interior from the mask using the DynamicPaintBrush
Apply mask
Use CT to Reduce red curve, Apply
The first color image in SHO. Left one has not had excess green or magenta dealt with, the right one has. see detail in the text.
12. Do Nonlinear NR
Use ACDNR: lightness: set to 2.6 with lightness mask, and chrominance set to 6.0 with lightness mask
Adjust mask mid tone to 0.39, Shadows to 0.22.
Test preview regions to confirm
Apply
Nonlinear Image preview section showing the existing noise patterns (Click to enlarge)
Same region after ASDNR is applied (Click to enlarge)
13. Create Color Masks and Enhance
Blue mask - use ColorMask script with Blue chosen
Adjust mask
Fix star-rings in the mask by eliminating them with the DynamicPaintBrush or CloneStamp tool
Run deconvolution on the mask to smooth it out
Boost mask contrast with HT to recover loss of intensity from Convolution operation
Green mask - ColorMask script with Green Chosen
Adjust mask as in the blue example above
14. Boost Local Contrast
LHE default kernel radius 64 contrast limit 2.0 Amount: 22, Apply
15. Enhance Colors
Create a range mask with SelectRange to get just the nebula
Use DynamicPaintBrush to eliminate the outside portion of the mask.
Run deconvolution stddev 10, 2X to soften that mask
Apply mask - use CT to increase saturation
Create a blue mask using the ColorMask script
DynamicPaintBrush to eliminate the areas outside the nebula
Run Convolution, stddev 10, 2x
Apply mask
Use CT to boost the Blue layer and reduce the Green layer
Use the GAME script to cover the hollow part of the heart nebula
Apply and use CT to boost blue curve and the reduce the red curve slightly
Now boost the yellow edge portion of the nebula
Use ColorMask to create a mask of the Yellow areas
Use DynamicPaintBrush to get rid f areas outside the nebula
Apply the mask
Use the CT to boost the Sat
Adjust the image of the outer portion
Copy the range mask
Fill in central voids with the DynamicPaintBrush
Apply the mask, invert it
Increase the Red Layer and the Green Layer with CT
Darken lower levels with the K/RGB curve
The Blue mask (Click to enlarge)
Range mask modified to cover the whole area of the nebula (click to enlarge)
The Yellow mask, modified to remove regions outside the nebula (click to enlarge)
After color adjust. (click to enlarge)
16. DarkStructure Enhance
Run the DarkStructureEnhance script with default paramaters
17. Sharpening
Sharpen with MLT, 4 layers, with parameters as shown below - note - no mask used.
Apply LHE with a kernel radius of 24, contrast limit 2.0, amt of 0.24
18. Do Star Reduction
Run EZ-Star Reduction with defaults.
19. Shift over to Photoshop
Export image as a TIFF file - 16 bit.
Run Photoshop, load image
Add my custom watermarks
Save image.
Export a clean image - full res - no watermarks
Export a full res image - with watermarks
Export a subsampled image with higher jpeg compression for web use.
Final Note - this is the FIRST image where 100% of the image processing was done in Pixinsight and none in Photoshop. To do this, I need up create and engineer a huge selection of mask files. The Project files for this are filled with them! See below!
More Information
There is not a lot of information to be found on this target, but here are a few sources I found:
Wikipedia: IC 1805 The Heart Nebula
The Sky Live: : IC 1805 The Heart Nebula
Capture Information
Light Frames
44 x 300 seconds, bin 1x1 @ -15C, unity gain, Astronomiks 6nm Ha Filter
49 x 300 seconds, bin 1x1 @ -15C, Unity gain, Astronomiks 6nm OIII Filter
46 x 300 seconds, bin 1x1 @ -15C, unity gain, Astronomiks 6nm SII Filter
Total of 11.58 hours
Cal Frames
25 Darks at 300 seconds, bin 1x1, -15C, gain unity
25 Dark Flats at Flat exposure times, bin 1x1, -15C, gain unity (taken for each night)
Flats:
15 Ha Flats
15 OIII Flats
15 SII Flats
Capture Hardware
Scope: Askar FRA400 73MM F/5 Quintuplet Astrograph
Guide Scope: Sharpstar 66EDPHII
Camera: ZWO ASI1600mm-pro with ZWO Filter wheel with ZWO LRGB filter set,
and Astronomiks 6nm Narrowband filter set
Guide Camera: ZWO ASI290Mini
Focus Motor: Pegasus ZWO EAF 5V
Mount: Ioptron CEM 26
Polar Alignment: Ipolar camera
Software
Capture Software: PHD2 Guider, Sequence Generator Pro controller
Image Processing: Pixinsight, Photoshop - assisted by Coffee, extensive processing indecision and second-guessing, editor regret and much swearing….. Given the problems on this image, more than the usual whining….
The portable scope platform is supposed to be, well, portable. That means light and compact. In determining how to pack this platform for travel, I realized that the finder scope mounting rings made no sense in this application and I changed them out with something both more rigid and compact - the William Optics 50mm base-slide ring set.