Triangulum Galaxy (M33)

The Triangulum Galaxy is a spiral galaxy in the constellation Triangulum and is estimated to be 3 million light-years away from Earth. Messier 33 is supposedly the third-largest member of the Local Group of galaxies behind the Milky Way and Andromeda. Astronomers believe that the Andromeda Galaxy (M31) contains the Triangulum galaxy as one of its many satellites.

Famous astronomer Charles Messier discovered this galaxy in 1764 and later published it as Messier 33 in his Catalog of celestial objects. Although the presence of M33 becomes evident in a long-exposure photograph, it can be difficult to observe if you don't know what you are looking for.

Location & Best Time to See it

The Triangulum Galaxy is located within the constellation Triangulum and between the constellations Andromeda and Aries. An easy way to find the approximate location of Messier 33 is to use an astronomy-dedicated app like Stellarium. From there, you can attempt to spot a triangle-shaped constellation and move upwards. The photo below from Stellarium is a good representation of where to look to find the Triangulum Galaxy in the night sky.

From mid-northern latitudes, it reaches an apparent altitude high enough in the southern sky for visual observation or photograph. However, it is not circumpolar, so the best to view it at its peak in the sky close to the zenith to minimize the effects of turbulence in the air and localized light pollution, which is from September to November.

Photographing the Triangulum Galaxy

Messier 33 is a bright target in the night sky; however, it requires a significantly large amount of exposure time to capture the incredible detail hidden within it. Because of the Triangulum Galaxy's large apparent magnitude, you can faintly capture the core and a small portion of the arms of this galaxy with just a 2-minute exposure shot. This is really helpful when trying to locate Messier 33 through your camera and telescope. Once you have the Triangulum Galaxy in frame and tracking, we will need to take the four main calibration frames (light, dark, flat, and bias) for deep sky objects, and stack these shots together through DeepSkyStacker. A good tutorial on how to use the software is here.

Here is how to take the four main calibration frames:

Light Frames - These are your signal frames; the instructions above are how to take these.

Dark Frames - These frames' purpose is to increase your photo's signal-noise ratio. Keep the same settings you had for your light frames and cover your lens/telescope with the lid. 

Bias Frames - The purpose of these frames is to reduce the noise in your photo. Keep the same settings on your camera for your light frames, change the exposure time to the fastest it can possibly be, and cover your lens/telescope with the lid. 

Flat Frames - The purpose of these frames are to eliminate vignetting/light falloff and other artifacts in your image due to dust, dirt, or smudges on the sensor or telescope in your photo. These are tricky. In simple terms, cover your lens/telescope with a white shirt and point it at a constant light source, like the morning sky. Then experiment with the exposure times until the histogram looks like the one below. This is shown below for monochrome and color cameras.

My photo of Messier 33 below was captured using an unmodified Canon Rebel EOS T3i (600D) DSLR camera and a refractor telescope (100mm Aperture, 900mm focal length).

Triangulum Galaxy Details:

• Messier: 33

• NGC: 0598

• Object Type: Spiral Galaxy

• Constellation: Triangulum

• Distance: 2.73 million light-years

• Apparent Magnitude: +5.7

• Apparent Size: 73 x 45 Arc Minutes

Resources:

Messier 33 - The Triangulum Galaxy (NASA) 

StarCharts - Triangulum Galaxy

Gallery of Triangulum Galaxy