This is the rich region of clusters and nebulosity in the constellation of Gemini, with the Jellyfish Nebula, IC 443 at bottom near the orange star eta Geminorum. IC 443 is a supernova remnant. The larger region of fainter, diffuse nebulosity at left is IC 444. The loose star cluster embedded in it, with the blue star 12 Gem, is Collinder 89. At top right is the bright showpiece open star cluster Messier 35 with its smaller, more distant companion cluster NGC 2158 at lower right from M35. This is a blend of 8 x 5-minute exposures at ISO 800 unfiltered with 6 x 10-minute exposures at ISO 1600 shot through an Optolong L-Enhance dual-band nebula enhancement filter (it lets through only Oxygen III blue-green and Hydrogen-alpha red to really enhance the nebulosity). All exposures with the Canon EOS Ra mirrorless camera through the SharpStar HNT150 Hyperbolic Newtonian Astrograph at f/2.8, from home on a very clear moonless night January 27, 2020. All stacked, aligned and blended in Photoshop 2020.
A framing of the area in Gemini containing the large and bright star cluster Messier (M) 35 at right and the curving Jellyfish Nebula, aka IC 443, at left, near the star Propus or eta Geminorum. The small but rich star cluster below M35 is NGC 2158 . The blue reflection nebula above the Jellyfish is IC 444. The Jellyfish is a supernova remnant some 1500 light years away and about 21 light years across. This is a stack of 6 x 8-minute exposures and 8 x 4-minute exposures, all at ISO 800 with the Canon EOS Ra red-sensitive camera, and through the SharpStar 94mm apo refractor at f/4.5 with the EDPH field flattener/reducer. The later shorter exposures were shot with the field getting low in the west and into the murk and light pollution on an early April evening. I shot these as part of testing the new SharpStar 94mm EDPH refractor. No nebula filter was employed here. Luminosity masks with Lumenzia applied as well as a layer of contrast boost applied to the nebulas using the Pro Contrast filter in the Nik Collection Color EFX Pro set of filters. All stacking and blending was with Photoshop. No dark frames taken or applied, just dithering applied between exposures to shift each image by 5 pixels. Auto-guiding, camera control and dithering were with the Lacerta MGEN3 stand-alone auto-guider.
The Jellyfish Nebula, IC 443, at left near the star Eta Geminorum at left. IC 443 is a supernova remnant. At upper ight is the bright open star cluster Messier 35. The smaller and fainter star cluster below M35 is NGC 2158. M35 is 2500 light years away but NGC 2158 is 16,500 light years away. This is a stack of 10 x 6-minute exposures with the 92mm TMB apo refractor at f4/4 with the Borg 0.85x field flattener/reducer and the filter modified Canon 5D MkII at ISO 800. Taken from New Mexico.
