Contains: M 103, NGC 581
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Messier 103 (M103, NGC581) in Cassiopeia

Technical card

Imaging camera: Canon 600D

Focal reducer: Celestron f/6.3 Focal Reducer

Software: Sequator

Resolution: 5202x3465

Dates: Feb. 13, 2018

Frames: 180x15" ISO1600

Integration: 0.8 hours

Darks: ~24

Flats: ~24

Avg. Moon age: 27.36 days

Avg. Moon phase: 5.25%

Bortle Dark-Sky Scale: 6.00

Temperature: -1.00 job: 1929216

RA center: 23.236 degrees

DEC center: 60.619 degrees

Pixel scale: 0.686 arcsec/pixel

Orientation: 313.818 degrees

Field radius: 0.596 degrees

Locations: Home Stockport, Stockport, Cheshire, United Kingdom


Tonight's target was the open cluster M103 in Cassiopeia. The images collection was plagued by dew accumulation on the corrector plate, despite the dew shield I put on. I think that's the reason why a faint halo is present around the brightes stars. The whole telescope was completely soaked...a mess...but at least lesson learned...don't go outside if the forecast is high relative humidity!

180x15s light frames @ 1600 ISO
24 dark frames
24 flat frames

Messier103 (also known as M103, or NGC581) is an open cluster where a few thousand stars formed in the constellation Cassiopeia. This open cluster was discovered in 1781 by Charles Messier's friend and collaborator Pierre Méchain. It is one of the most distant open clusters known, with distances of 8,000 to 9,500 light-years from the earth and ranging about 15 light-years apart. There are about 40 member stars within M103, two of which have magnitudes 10.5, and a 10.8 red giant, which is the brightest within the cluster. Observation of M103 is generally dominated by the appearance of Struve 131,though the star is not a member of the 172-star cluster. M103 is about 25 million years old (from Wikipedia).



Michele Vonci



Uncropped version

Sky plot

Sky plot


Messier 103 (M103, NGC581) in Cassiopeia, 


        Michele Vonci

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