IC 443 is a large supernova remnant (SNR) in Gemini about 5,000 light years distant. Its age remains uncertain, but is estimated to be between 3,000 and 30,000 years. The field of view shown is approximately 2 x 3 degrees — this is a large object from our perspective. IC 443 emits strongly at visible wavelengths, including the emission lines of the classic Hubble palette (Ha, SII, and OIII). The region towards the left has a common moniker — the “Jellyfish Nebula”.
Technical details are as follows:
All data was acquired at MYHY Observatory in the Philadelphia suburbs in 2018 using a Takahashi FSQ 106N @ f/5 with an SBIG STL11K on a Paramount ME. All subexposures were 30 minutes with 3 nm Ha/OIII and 9 nm SII filters (Ha/SII unbinned, OIII binned 2×2), a total of 20 hours Ha, 17 hours SII, and 15 hours OIII. The image was assembled as an (Ha + SII) lum layer over the SII-Ha-OIII RGB layer. The Hubble palette calls for SII as the red channel, Ha as the green channel, and OIII as the blue channel — given the extremely strong Ha signal that would have dominated the image with mostly green tones, I deliberately suppressed the Ha signal to allow the others to show through — as always, astrophotography requires aesthetic decisions that render the final product art as opposed to science.