IC 443 (also known as the Jellyfish Nebula and Sharpless 248) is a Galactic supernova remnant (SNR) in the constellation Gemini. On the plan of the sky, it is located near the star Eta Geminorum. Its distance is roughly 5,000 light years from Earth.
IC 443 is an extended source, having an angular diameter of 50 arcmin (by comparison, the full moon is 30 arcmin across). At the estimated distance of 5,000 ly (1,500 parsec) from Earth, it corresponds to a physical size of roughly 70 light years (20 parsec).
The SNR optical and radio morphology is shell-like (e.g. a prototypical shell-like SNR is SN 1006), consisting of two connected sub-shells with different centers and radii. A third larger sub-shell, initially attributed to IC 443, is now recognized as a different and older (100,000 years) SNR, called G189.6+3.3.
Notably, IC 443 X-ray morphology is centrally peaked and a very soft X-ray shell is barely visible. Unlike plerion remnants, e.g. the Crab Nebula, the inner X-ray emission is not dominated by the central pulsar wind nebula. It has indeed a thermal origin. IC 443 shows very similar features to the class of mixed morphology SNRs. Both optical and X-ray emission are heavily absorbed by a giant molecular cloud in the foreground, crossing the whole remnant body from northwest to southeast.
Imaging telescopes or lenses: Selfmade Super Astrograph 8″ f4
Imaging cameras: SBIG ST- 8300M
Mounts: Skywatcher AZ EQ6 GT
Guiding telescopes or lenses: Selfmade Super Astrograph 8″ f4
Guiding cameras: ALccd5-IIm
Software: Fitswork, Adobe Photoshop CS5
Filters: Baader Planetariun Ha 7nm, Baader Planetarium Blue 1.25″, Baader Planetarium Green 1.25″, Baader Planetarium Red 1.25″, Baader Planetariun OIII 8.5nm
Accessories: TS 9mm OAG, Pal Gyulai Komakorrektor
Dates: Feb. 21, 2014
Baader Planetarium Blue 1.25″: 2×600″ bin 2×2
Baader Planetarium Green 1.25″: 2×600″ bin 2×2
Baader Planetariun Ha 7nm: 6×900″
Baader Planetariun OIII 8.5nm: 7×600″ bin 2×2
Baader Planetarium Red 1.25″: 2×600″ bin 2×2
Integration: 3.7 hours
Author: Petko Marinov
16 March 2014
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