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Derek Santiago | all galleries >> Galleries >> Galaxies > NGC 4236 LRGB
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NGC 4236 is a barred spiral galaxy in Draco. It is 11.8 mLy distant. Despite it being quite large and having an apparent magnitude of 10, it has a low surface brightness (24 mag/arc-sec2) and so is quite difficult to observe and image. In simple terms, apparent magnitude refers to the total measured light emitted by an object whereas surface brightness incorporates density. So a star and an extended galaxy may have the same magnitude, but the star will be much easier to see because of the galaxies low surface brightness. It is a member of the M81 group of galaxies, but is considerably dimmer than the more prominent members.

Imaging Camera: QSI640wsg
Imaging Scope: Celestron 9.25"Edge HD at f/7
Guide Camera: SX Lodestarx2
Mount: Avalon M-Uno Fast Reverse
Filters: Astrodon Gen II LRGB
Exposure: 6 hours Lum, 5 minute subs unbinned, 2 hour each RGB, 2.5 minute subs binnedx2
Capture: APT
Processing: CCD Stack and PS CC
Date: 4/6/21-4/8/21
Sky conditions: below average seeing, bortle white skies, SQM 17.35 mag/arc-sec2
Location: My front driveway. Morristown, NJ

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