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 during the fall months of 2018. I used an SBIG STL 11k with Astrodon 3 nm Ha/OIII filters and a Baader 9 nm SII filter; Takahashi FSQ 106N; Paramount ME. All subexposures were 30 minutes (Ha/SII unbinned, OIII binned 2×2 — I had difficulty getting any unbinned OIII data from the suburbs, explaining why I decided to go with 2×2 binning for the OIII) — there was a total of 20 hours Ha, 17 hours SII, and 15 hours OIII . Processing was accomplished using the following workflow: Maxim for data reduction; PixInsight for image alignment, integration, and initial data stretches; Photoshop for final stretches, color tweaking, gradient management, noise reduction, etc. 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. .