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Heart and Soul Nebulas (SH 190 and 199)

November 2014 - January 2015

The Heart and Soul Nebulas are two bright nebulas on the border of Cassiopeia and Perseus. They are cataloged in the Sharpless catalog of bright Hydrogen rich areas.  Portions also have NGC or IC designations.

I imaged these in an earlier project in 2012, but at that time I was using an 8300 based camera with a narrow Field of View.  Consequently the project required 9 separate segments.  When I was not able to complete it I realized that the 8300 was not suitable to the type of projects I was interested in shooting.  This led to my acquiring the 16803.

The processing of these images was greatly influenced by the 2014 Katonah NY workshop.  The 2012 project was up to this point one of my favorite works.  Applying what I learned in Katonah gives an image that is much richer in color.  Green (Hydrogen) dominated the previous image, hiding the rich colors along the edges of the nebula that become apparent in the more balanced image.  Also note the Purple area on the upper right of the Heart.  This was lost before the Katonah processing.

Area map of SH 190 199

Zoomed map of SH 190 -199

Annotated Image

Annotated Image of SH190 199

Choice of Palettes

For this image I only used the SHO Palette.  Otherwise known as the Hubble Palette.  This maps

Hubble Palette

Zoomable Image in SHO

The full size image is 6457 x 4954.  The following will allow the reader to zoom into the image to explore it more closely.


Soul Nebula (SH 199)

This is a reduced resolution image of just the Soul (Sharpless 199).

Soul Nebula SH 199

Note the yellows (S+H) along the edges of the nebula and the aquas (O+H) in the center.  Some regions contain enough Sulfur to be reddish (with this processing).

Note the Open Cluster on the right side of the nebula.

Heart (SH 190)

The Heart (Sharpless 190).  I was not able to complete the Heart with the 8300 and thus it remained a monocolor Hydrogen project.  Like the Soul the edges have hints of yellow with Aqua in the centers. Note especially the purple bands on the upper right corner.  Those are regions rich in Sulfur and Oxygen. This framing crops the full structure. Please consult the zoomable image above.

Heart Nebula

Processing Details

Data was collected between November 2014 and January 2015 at -30C.  While collecting data for this project I switched to using APCC.  This greatly improved my tracking and reduced the number of rejects. Still I took about 50% more images than what I used.

Hydrogen 21x900
Oxygen 21x900
Sulfur 24x900

Color Calibration

As I learned in Katonah instead of trying to preserve the relative levels of the filters we used color calibration on the strong nebula as a "white" reference.  In addition before color calibration I adjusted the SHO levels by ratio of 5:1:2.  This brought them closer to even before Color Calibration was done. Adjusting the levels this way gives more balanced image.  Otherwise Hydrogen would be the only thing displayed.

Managing star shapes and size

One of the most important things we learned at Katonah was how to build good star masks. PixInsight provides a tool for doing this directly, but it is difficult to fine tune the results of the tool.  At the workshop we learned to use MLT to perform an initial extract.  We then used Curves, MT, and convolution in whatever combination gave us a satisfactory mask. Once I had the masks I protected the stars particularly from the sharpening operations. Different operations required different masks.  Sharping operations used relatively broad masks while color operations used narrow masks.

Many of these techniques are also covered in IP4P section 3 PI-11 and PI-12.

Managing star colors

One of the other uses for the mask was to correct the horrid star colors that result from using the narrowband filters after aggressive color calibration.  With a suitable mask from above one can then apply corrections.  We were taught to do this either by removing saturation or by overwriting with a luminance.  For this project I used the latter.

Here is an example of before and after.  The Before image is 2x to make the rings easier to see

Demonstation of color ring in NB


Ultimately the root problem with "raccoon eyes" is that "color" in the image is formed by combining two images that are red (Hydrogen and Sulfur) and one that is aqua (Oxygen).  Thus we start far from anything that would produce a balanced white result.  This is compounded by greatly magnifying some channels which increases the area at the edges of stars.  That is data loss and there may be little that can be done.

At Katonah we learned to fix the star colors immediately after color calibration.  An image produced using that technique was almost the final image in this project.  I decided to go back and instead try making the color correction late in the processing.  The "H" version being displayed is the result of that change.  To my eyes the halos are eliminated without substituting gray rings around the stars. Some rings remain, but remember the halos are a data loss.  Your choice is rings or larger stars.  The "H" version opted for slightly larger bright stars, but better small stars.

In addition I am following the IP4P set of tutorials. Section 3 PI-12 contains a number of suggestions on using the Color Saturation tool to correct the star halos.  This allows the precise color of the halo to be mitigated. In addition this tutorial and the previous also cover some of the same mask techniques covered at Katonah.

MidLevel details.

Using curves on a Luminance extract it is possible to isolate the mid level intensities (25-60%) and then apply color saturation or boost the luminance. Either or both bring out details in the more subtle portions of the nebula.

Copyrights For Photos

Creative Commons License
Except as noted,all work on this site by Robert J. Hawley is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 3.0 United States License. This permits the non commercial use of the material on this site, either in whole or in part, in other works provided that I am credited for the work.