IC 443 (also known as the Jellyfish Nebula and Sharpless 248 (Sh2-248)) is a galactic supernova remnant in the constellation Gemini. It lies adjacent to the emission nebula Sharpless 249, a star forming region, in the left half of this image. Some really smart folk who’ve been studying this believe that IC 443 may be the remains of a supernova (Star Explosion) that occurred 3,000 – 30,000 years ago. The same supernova event likely created the neutron star CXOU J061705, the collapsed remnant of the stellar core. The shock wave from the explosion produced the particularly intricate lacework of nebulosity that makes up the Jellyfish. The nebula, which is about 5,000 light years away, is adjacent to a rich region of star formation called Sharpless 249. IC 443 is one of the best-studied cases of supernova remnants interacting with surrounding molecular clouds.
The region is bordered by two very bright stars – Propus to the right and Tejat on the left. I find these two by lining up Alnitak (bottom star in Orions Belt) with the bright red star Betelgeuse and continuing about as far again. The two little stars are visible to the naked eye.
Eta Geminorum is the star’s Bayer designation. The traditional names Tejat Prior, Propus (from the Greek, meaning forward foot) and Praepes and Pish Pai (from the Persian Pīshpāy, پیشپای, meaning foreleg). In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN) to catalog and standardize proper names for stars. The WGSN’s first bulletin of July 2016 included a table of the first two batches of names approved by the WGSN; which included Propus for this star. Between the Propus and Tejat are several faint areas of nebulosity. IC 443, the jellyfish while further east around μ Gem is the emission nebula Sh 249 (left side of image). In between is the small faint emission nebula IC 444 (the bridge between the jellyfish and Sh 249).
Image captured with a ASI071MC Pro camera attached to a WO Z73 refractor telescope riding a SkyWatcher EQ6r Pro equitorial mount. Image acquisition with APT and processed manually in PixInsight. Exposures of 240s(28), 360s(94), 600s(32) – totaling 996 minutes, or 16.6 hours. All at unity gain and cooled to 20f. Calibration masters utilized.
Clear skies!
