Last night the sky was clear, but the light Pollution was horrendous.  It was still cold enough to where I didn’t want to travel to the lakes, and the Sodium lamp 20 yards from me polluted most of the Western Sky.  Initially I was going to image the Pleiades, but I thought I would wait for March 25th for the Moon and Pleiades conjunction.  So I decided on imaging M42, most likely my last of the year.  But if I get my new Optolong L-Ultimate filter soon I might give M42 another go.  As an aside, I am close to reaching a decision on purchasing the ASI2600MC camera, but even if I do, the camera won’t arrive for sometime.  Anyway I think I made a decent design on what to image last night.

The revision is because I wanted to see what the PixInsight script "Dark Structure Enhance".  Since summer is coming I am thinking I will try to image as much Dark Nebulae as I can.Messier 42 (M42), the famous Orion Nebula, is an emission-reflection nebula located in the constellation Orion, the Hunter. With an apparent magnitude of 4.0, the Orion Nebula is one of the brightest nebulae in the sky and is visible to the naked eye. It lies at a distance of 1,344 light years from Earth and is the nearest stellar nursery to Earth. The nebula has the designation NGC 1976 in the New General Catalogue.The Orion Nebula is very easy to find as it is located just below Orion’s Belt, a prominent asterism in the winter sky. The nebula appears as the fuzzy middle star in Orion’s Sword, which is formed by a vertical row of three stars (i.e. two stars and M42) south of Orion’s Belt. The nebula can easily be seen in binoculars and small telescopes. Covering more than a degree of apparent sky, the nebula appears over four times the size of the full Moon.Small telescopes at higher magnifications will reveal the four brightest stars in the Trapezium Cluster, an open cluster of young, hot, massive stars that were formed within the Orion Nebula. The four stars form a trapezoidal shape and energize the surrounding nebulosity.Orion constellation is easy to identify for its prominent hourglass shape, with the bright supergiants Betelgeuse and Rigel at the upper left shoulder and lower right foot of the celestial Hunter. Orion’s Belt, formed by the bright stars Alnitak, Alnilam and Mintaka, is in the centre of the hourglass figure. The best time of year to observe M42 is during the winter months, when Orion is high in the sky in the evening.Messier 42 occupies an area of 65 by 60 arc minutes of apparent sky and its spatial diameter measures 24 light years. The nebula has a mass 2,000 times that of the Sun and contains associations of stars, reflection nebulae, neutral clouds of dust and gas, and ionized gas. It is part of the Orion Molecular Cloud Complex, a larger region of nebulosity that also includes the famous Horsehead Nebula, the Flame Nebula, the emission nebula Barnard’s Loop, De Mairan’s Nebula (M43), and the reflection nebula.

Messier 78.The Orion Molecular Cloud Complex covers an area of more than 10 degrees, which is more than half of Orion constellation.The Orion Nebula is a place of massive star formation and one of the most studied deep sky objects in our vicinity as it allows astronomers to study the process of stars forming from clouds of dust and gas and the photo-ionizing effects of massive young stars that are responsible for the nebula’s glow. New stars are forming throughout the nebula. The temperature in the central region is up to 10,000 K and considerably lower around the edges.The stars in the Trapezium Cluster emit ultraviolet radiation, heating the surrounding gas and illuminating the nebula. Their stellar winds are also eroding and sculpting the nebula. Most of the ultraviolet ionizing radiation comes from Theta-1 Orionis C, the most massive of the four bright stars in the Trapezium Cluster and one of the most luminous stars known.Theta-1 Orionis C has the spectral classification O6pe V and the highest surface temperature (40,000 K) of any star visible to the naked eye. It emits 3 to 4 times more photoionizing light than the second brightest star in the cluster, Theta-1 Orionis A.Different parts of the Orion Nebula have been given different names. The bright regions to the sides of the nebula are known as the Wings and the dark lane stretching from the north toward the illuminated region is called the Fish’s Mouth. The wing extension to the south is known as the Sword, the fainter extension to the west is called the Sail, and the bright nebulous region under the Trapezium Cluster has been nicknamed the Thrust.Messier 42 contains hundreds of very young stars, less than a million years old, and also protostars still embedded in dense gas cocoons. The nebula is home to about 700 stars in different stages of formation. The youngest and brightest members are believed to be less than 300,000 years old, and the brightest of these may be as young as 10,000 years old.The Hubble Space Telescope has observed more than 150 protoplanetary disks, or proplyds, within M42. These are systems in the first stages of solar system formation.
In about 100,000 years, most of the nebula will be gone and leave behind a bright, young open cluster of stars surrounded by wispy remains of the former nebulosity, similar to the Pleiades.FACTSThe Orion Nebula has been known by many cultures since ancient times. It may have been mentioned in the Mayans’ creation myth of the Three Hearthstones. In the myth, the nebula represents the embers of a fiery creation.

The nebula was not mentioned by Ptolemy, Al Sufi or Galileo, even though they documented their observations and listed a number of other objects in their works. Ptolemy catalogued the nebula as a single bright star in 130 AD, as did Danish astronomer Tycho Brahe in the late 16th century and German astronomer Johann Bayer in 1603. Bayer catalogued it as Theta Orion in his star atlas Uranometria. Galileo saw several faint stars in the region in 1610, but did not see the surrounding nebula.The first to identify M42 as a nebula was the French astronomer Nicolas-Claude Fabri de Peiresc, who observed it with a refractor on November 26, 1610.Swiss Jesuit astronomer and mathematician Johann Baptist Cysat is credited for the first published observation of the Orion Nebula. The nebula was included in his monograph on the comets, published in 1619. Cysat compared the nebula to a bright comet he had observed in 1618 and described its appearance through his telescope: “one sees how in like manner some stars are compressed into a very narrow space and how round about and between the stars a white light like that of a white cloud is poured out.”