IC 434 Horsehead Nebula
Curious note as was searching information I came into this:
"Popular and respected modern astronomical reference works such as "Burnham's Celestial Handbook" (52),  written by a staff member at Lowell Observatory, often cited by many other volumes and articles, fail to give W. H. Pickering his due credit for producing the first photographs of the Horsehead nebula, and the present author presumes to suggest why. The paper announcing the discovery of what we now call the Horsehead, ''Detection of New Nebulae by Photography'' is included in the Harvard College Observatory Annal, Volume 18. It is presented without attribution, in the publication edited by Edward C. Pickering, the director. The unidentified author refers to his previously published discussion of the advantages of the wide field doublet, suggesting conclusively that it has been written by the photographic expert, brother William. Furthermore, the younger Pickerings's assertive, fluid, and detailed style is clearly present throughout; indeed, the famous British astronomer E. Walter Maunder credits the paper to W. H. Pickering in the Journal of the British astronomical Association, Volume I, published in 1891. (53)
W. H. P. himself covers exactly the same ground in his later signed paper that comprises the entirety of the Harvard College Observatory Annal for 1895, quoted extensively in paragraphs above.
We come now to a most remarkable and unexpected episode in the saga. The Orion nebula plates taken by Pickering with the Bache telescope were given to a staff member, one Mrs. Williamina Paton Fleming, to examine, categorize, measure, and catalog new objects."  http://web.archive.org/web/20070312071923/home.earthlink.net/~astro-app/horsehead/B33-19thC_4.htm



The Horsehead Nebula (also known as Barnard 33 and IC434 ) is a dark nebula in the constellation Orion. The nebula is located just to the south of the star Alnitak, which is farthest east on Orion's Belt, and is part of the much larger Orion Molecular Cloud Complex. It is located approximately 1500 light years from earth.

Heavy concentrations of dust in the Horsehead Nebula region and neighbouring Orion Nebula are localized into interstellar clouds, resulting in alternating sections of nearly complete opacity and transparency.[9] The darkness of the Horsehead is caused mostly by thick dust blocking the light of stars behind it.[10] The lower part of the Horsehead's neck casts a shadow to the left.[11] The visible dark nebula emerging from the gaseous complex is an active site of the formation of "low-mass" stars. Bright spots in the Horsehead Nebula's base are young stars just in the process of forming.

Interesting study
A bimodal dust grain distribution in the IC 434 H ii region l
"Conclusions. The dust inside IC 434 is bimodal. The characteristics of population A are remarkable and cannot be explained by current dust models. We argue that large porous grains or fluffy aggregates are potential candidates to explain much of the observational characteristics. Population B are grains that match the classical description of spherical, compact dust. The inferred optical properties are consistent with either very small grains, or large grains in thermal equilibrium with the radiation field. Our results confirm recent work that stress the importance of variations in the dust properties between different regions of the ISM. "  https://www.aanda.org/articles/aa/full_html/2015/04/aa24799-14/aa24799-14.html

NGC 2024 Flame Nebula
The Flame Nebula, designated as NGC 2024 and Sh2-277, is an emission nebula in the constellation Orion. It is about 900 to 1,500 light-years away.
The bright star Alnitak (ζ Ori), the eastern most star in the Belt of Orion, shines energetic ultraviolet light into the Flame and this knocks electrons away from the great clouds of hydrogen gas that reside there. Much of the glow results when the electrons and ionized hydrogen recombine. Additional dark gas and dust lies in front of the bright part of the nebula and this is what causes the dark network that appears in the center of the glowing gas.
A study of NGC 2024 suggest that the stars on the outskirts of these clusters are older than those in the central regions. They used Chandra data on the brightness of the stars in X-rays to determine their masses. Next, they found out how bright these stars were in infrared light using data from Spitzer, the 2MASS telescope, and the United Kingdom Infrared Telescope. According to the new results, the stars at the center of NGC 2024 were about 200,000 years old while those on the outskirts were about 1.5 million years in age.  https://en.wikipedia.org/wiki/Flame_Nebula#/media/File:NASA-FlameNebula-NGC2024-20140507.jpg

Alnitak
The easternmost of the three stars that make up Orion's Belt, Alnitak is a binary. The primary is an O-type supergiant, one of the most luminous of star-types, meaning that shines as brightly as magnitude +1.7 despite being more than 700 light years away.
Though only some twelve times the Sun's diameter, this supergiant star emits extraodinary levels of energy: it is some 9,000 times more intrinsically luminous than the Sun in visible light, and produces more than 150,000 times as much energy across the entire spectrum. https://www.glyphweb.com/esky/stars/alnitak.html

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One of the projects that Maurizio has wanted to complete for a long time and of course the vision of this iconic nebula always attracted us since the beginning. Our first image of the Horsehead Nebula was taken during a star party in Sept. 2019 and Maurizio processed it and it is the one that is exposed here, only 3,3 minutes long... https://www.astrobin.com/x4oj3c/O/

Late last year and early this year taking advantage of the benevolence of an unusual winter and clear skies, Maurizio was able to achieve several sessions in our backyard as in Bortle 4 skies that helped a lot in getting a better capture of this beautiful and fascinating nebula.

As usual, the L-Pro stack was made as a base of stars, but this time I put together the stars obtained in a session with the Triad Ultra filter where they came out particularly beautiful and with excellent colors. Stacked both DSS and Siril on normal and 2 drizz from sessions done with Extreme and Triad Ultra together. Additionally, the extraction of Ha and [OIII] was carried out.

One of the stacks was applied part of the tools offered by Siril: Photometric color calibration, background extraction and Histogram Transformation manually. Level, arcsinh curve, noise gradient, S curve were applied to the other, and both were finished working in CamRaw. The noise reduction part was came aout nicely, and in both it was applied Noise Exterminator with a mixture of Denoise. The details were achieved using also the Ps unsharp mask tool.

Ha and [OIII] were also worked on to achieve a luminance base with details in which it was assembled by mixing Ha 65% and [OIII] 35%. It is really fascinating to observe these two gases separately and how the cloudiness of that area is prominent.  The B&W image turn out very beautiful, we really like that version too.  I'm planning to do some other versions in the future with this material.



Probably the most troublesome and tedious part was regarding the bright stars in the area. And when using a Newton the reflection edges end up being very extended. Neither Starnet V2++ nor StarExterminator can handle them and you have to clean the image of those spikes, additionally the halos left by the filters are very accentuated but like everything it is solvable.

The final version received a fine touch by Maurizio and I think it given a neccesary contrast in the image.

A note regarding the stars in the area, at the top left of the area (outside of our image) is the star Alnilam. Maurizio had to framed in other position because when he started the project the luminosity of that star and according to the angle of inclination of the telescope, causes an internal reflection and the test frames presented a strong beam of light in that area. Reviewing the images to mark the ones that have a satellite (54 of 293 has path satellite in this project), I found that some had internal reflections even from the primary mirror, I did a test and fortunately in the final stack the noise reflection did not appear.

We appreciate your visit and wish you the best of skies!

Processed October-November 2022