A beautiful galaxy in Canes Venatici



Messier 106 (M106) is a spiral galaxy located in the constellation Canes Venatici, the Hunting Dogs.M106 lies at a distance of 23.7 million light years from Earth and has an apparent magnitude of 9.1. It has the designation NGC 4258 in the New General Catalogue.Messier 106 occupies an area of 18.6 by 7.2 arc minutes of apparent sky, corresponding to a spatial diameter of 135,000 light years. It is similar in size and luminosity to the Andromeda Galaxy (M31) and is one of the brightest, largest nearby galaxies.M106 has a high surface brightness and can be seen in binoculars, which reveal a faint patch of light. Small telescopes show a diffuse patch with a brighter centre, while 8-inch telescopes reveal more details of the galaxy’s structure. Large amateur telescopes show the galaxy’s spiral arms.Messier 106 lies along a line drawn from Phecda (Phad), Gamma Ursae Majoris, the star marking the bottom of the Big Dipper toward the handle, to Cor Caroli, Alpha Canum Venaticorum, the brightest star in Canes Venatici constellation. M106 can also be located by extending the line from Dubhe, Alpha Ursae Majoris to Phecda. Dubhe is the northern of the Pointer Stars, the two stars of the Big Dipper that point the way to Polaris in Ursa Minor.

Technical card

Telescope: OOUK AG16

Coma Corrector: 3inch ASA

Camera: Atik11000

Filters: Chroma 2inch

Mount: Paramount MEII

Location: Southern Arizona

Processing details

I had great fun processing this target. first I started by analyzing how good were my calibration frames as I have noticed some dead columns appearing in the final image despite the great sigma and Windsor clipping algorithms I was using. I have tried very aggressive rejection to no avail. I started using Astropixel Processor and I have to say that I am impressed with the amount of statistical tools available for post-processing. I created a bad pixel rejection map that identified all the bad columns as well hot and cold pixel.Here is a JPEG export of the BPM.

Oh it is ugly I know. However, this is a great way to remove all the bad columns and pixels. The end result is a clean background with zero artifacts which is exactly what we are after here. PRISM can, intelligently, figure out which columns are bad and remove them extremely well.