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​                                                            M33 - The Triangulum Galaxy

    The Triangulum Galaxy (also known as M33) that is about 3 million light-years away from Earth. While its mass is not well understood - one estimate puts it between 10 billion and 40 billion times the sun's mass - what is known is it's the third largest member of the Local Group, or the galaxies that are near the Milky Way. Triangulum also has a small satellite galaxy of its own, called the Pisces Dwarf Galaxy. Under dark sky conditions, M33 is just barely visible with the naked eye in the constellation Triangulum, just west of Andromeda and Pisces.
    Among the galaxy''s most distinctive features are ionized hydrogen clouds, also called H-II regions, which are massive regions of starbirth. Sprawling along loose spiral arms that wind toward the core, M33's giant H-II regions are some of the largest known stellar nurseries, sites of the formation of short-lived but very massive stars. Intense ultraviolet radiation from the luminous, massive stars ionizes the surrounding hydrogen gas and ultimately produces the characteristic red glow.
    Triangulum's official name of M33 would suggest at first that Charles Messier, who created the Messier catalog, was the one who discovered the galaxy. Messier was cataloging a list of deep-sky objects that were not comets in order to make searching for comets easier. M33 was noted on Aug. 25, 1764.However, the European Southern Observatory adds that the discovery could have been made by Italian astronomer Giovanni Battista Hodierna sometime before 1654, when his book "De systemate orbis cometici" ("About the systematics of the cometary orbit") was published. Some accounts say that Hodierna made an oblique reference in the book that could be interpreted as an observation of the galaxy.
    William Herschel (who is best known for discovering Uranus) also observed Triangulum in the late 1700s, and also noted a large region of gas within the galaxy that is today noted as NGC 604. M33 itself was considered a "spiral nebula," and it was unclear if M33 was part of the Milky Way Galaxy.
    By the 1920s, observations by Edwin Hubble noted that M33 is a separate "stellar system" based upon observations of Cepheid variable stars. These stars are often used to measure cosmic distances in space because their luminosity is the same no matter where they are located. Later observations of the galaxy revealed that it is approaching the Milky Way Galaxy at about 62,000 mph (100,000 kph). Some astronomers believe that Triangulum is "gravitationally trapped" by the massive Andromeda Galaxy that is also hurtling toward our galaxy, the European Southern Observatory stated.
                                                                                                                                                                                                      Elizabeth Howell,

                                                                   Imaging Notes  


    This is my first light with GSO 8" f/8 Ritchey Chretien. I have used it with Astro Physics CCDT67 reducer to get fast f/5.4 scope  and around 1000mm of focal length to widen my imaging options. Although you may find on some vendor websites, that this combination of GSO 8" f8 + CCDT67 + Crop DSLR will give pinpoint stars all around the field - they are wrong. I didn't tested other reduction factors of this Reducer, but at native 0.67x factor the results are unacceptable. There is very strong vignetting with even more field curvature with this setup.


    Making this image I had to crop around 20% of the field, which left me with galaxy just fit nicely in the view and still, you can note deformed stars around the corners, meaning, to get perfect image you'll have to crop even more. Using smaller chip size than crop DSLR will probably give better results or choosing smaller object then crop the image leaving just good central area. Anyway, most of the time I plan to use it at native 1624mm focal length for the small galaxies.


    Both of imaging nights were perfect with weather conditions, zero winds, low humidity and clear skies. I had hopes to go deeper than 6 hours during those nights, but first night I had some collimation problems. After attaching my DSLR with the Cooler Box I have noted a shift in collimation and it took me a good couple of hours to bring it back to shape. First good frames started to flow in the middle of the night, around 01:30 but the second night were much better. The temperature was cold and my Cooler Box got as low as -8°C giving me frames with EXIF temps of 0-1°C after 15 minutes of exposure.


    In total I've imaged for almost 9 hours, 35 frames were made but for the final stack only 25 of them made it giving me in total 6 hours and 15 minutes of exposure. On the forum pages many times photographers mention this galaxy as challenging object and I think one will understand why, when will image and process it by him self. I never count hours taking me to process an image, but there were a lot, with many times processing it from the scratch. All in all I'm very pleased with the new scope and very satisfied with the final result.


Technical Info:

Optics :               GSO 8" f8 Ritchey Chretien Astrograph @ f/5.4

Reducer:             Astro Physics CCDT 0.67x @ 0.67x

Camera :             Canon T3i (600D) Baader Mod           

Mount :               NEQ-6 Pro (Self Hypertuned/Belt Mod)​

Guiding Scope:    TS OAG9

Guiding Camera:  SX Lodestar            

Acquisition :         BackyardEOS 3.0.3   

Exposures :          25 x 900 sec @ ISO1600 - 6 Hours 15 Minutes

Stacking :            PixInsight 1.8 

​Processing :         PixInsight 1.8 

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