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M 52 and Bubble Nebula Area

June 2014 - July 2014
July 2017 - September 2017

The Hydrogen image for this area was the first panel in what became a huge project to map the Sharpless regions of Cassiopeia to Cygnus.  For the next two seasons I concentrated on filling out that mosaic with some notable diversions such as NGC 7000 (North American).  After the eclipse I decided to return to M 52 (my panel 1 of the mosaic) and see if I could shoot some O and S to go with the H.  Once I got the data I was underwhelmed with the S image.  So I quickly took some Nitrogen exposures.  These proved to be more interesting.

In most narrowband images of this object the "Hydrogen" component is actually H + Nitrogen.  The Nitrogen line is close enough to the H alpha line that it requires a 3 nm filter like I am using to separate the two. Doing so opens the possibility of viewing a nebula in a different way.  Note that the Hubble also uses 3 nm filters so their Hydrogen is just Hydrogen.


NH O+2*S palatte

Since neither the O or the S was a very strong signal I decided to combine them using one part O and 2 parts S to create the Blue channel. The rest of the processing is discussed below.

Location of Image

M 52 is located between the W of Cassiopeia and the house of Cepheus.   I framed the image to capture several of the nearby Sharpless objects which include the Bubble Nebula (NGC 7635).


Area map of M52/Bubble Area

Above is a map in Alt Az as viewed from the Observatory. 

Annotated Image

The image is presented rotated so north is up.  In this case the lines are RA/Dec instead of Alt/Az.


Annotated Image of M52/Bubble

M52 and Bubble

Here is M 52 and the Bubble at 1/2 resolution. 


NH-OS2 Image of M52 and Bubble


Zoomable Image in NH-OS2

The full size image is about 4096x4096.  The following will allow the reader to zoom into the image to explore it more closely.

R=N G=H B=O+2*Sulfur


Processing Details

Here are counts of the raw frames that were used for the various filters.  Naturally more images were taken.  These represented the ones that made the cut.


Filter
 Exposure
Hydrogen 31x900
Oxygen 20x900
Nitrogen 19x900
Sulfur 15x900

All images were processed by Pixinsight. 

Since Hydrogen is much much stronger than any of the other signals I had to dial it back so the image did not end up Green. Each of the channels were linear fit to the Hydrogen.  They were combined with PixelMath

	Red = Nitrogen
	Green = Hydrogen
	Blue = Oxygen + 2 * Sulfur

During Color Calibration the Hydrogen signal was reduced to 31% of the original signal.  The colors were then adjusted to bring the colors closer to saturation. Not only does this make for a more interesting image, it highlights the different distributions of the elements in the nebula.  The red areas really are areas where there is more Nitrogen.  Of course there would be even more Hydrogen had I not intentionally reduced its signal.

Note the region of SH 2-157 that is poor in Nitrogen, but contains Oxygen and Sulfur as well as Hydrogen.  This shows that the Nitrogen and Hydrogen filters really are capturing something different.

A number of dark nebula appeared when I used Dark Structure Enhancement.


Copyrights For Photos Creative Commons License
(c) 2017 Robert J Hawley.
Except as noted,all work on this site by Robert J. Hawley is copyrighted 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.

10/19/17