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.
A portrait of various emission nebulas in southern Gemini and into northern Orion. At top is the bright star cluster Messier 35, with the small more distant open star cluster NGC 2158 below and to the right of it. Left of centre is the shell-like supernova remnant, IC 443, aka the Jellyfish Nebula. The small blue reflection nebula above and to the left of it is IC 444 amid a field of fainter emission nebulosity. The round and bright nebula at bottom is IC 2174 in Orion, aka the Monkeyhead Nebula. It is mostly an emission nebula but has some blue reflection components. The smaller round red nebula above it is Sharpless 2-247. It appears to be an ionized HII region, as a form of bubble, but is not a planetary nebula. So this is a field of various forms of nebulas: emission, reflection and supernova remnants. Missing is an obvious planetary nebula or dark nebula. The orange star to the right of the Jellyfish is Propus, or eta Geminorum. This is a stack and blend of filtered and unfiltered exposures, the latter set maintaining the natural star colours, and avoiding the haloes introduced by the filters, particularly the L-eXtreme. The image is a blend of: 10 x 6 minutes at ISO 800 without a filter + 8 x 12 minutes at ISO 1600 with an Optolong L-eNhance dual narrow-band filter + 6 x 16 minutes at ISO 3200 with the Optolong L-eXtreme vary narrowband filter, the latter set taken at the end of the sequence when the field was quite low. Through masking the L-eXtreme images contributed only some of the nebulosity, particularly the subtle cyan fringes on the leading edges of IC 443 — it is the Oxygen III cyans that the L-eXtreme is good at picking up. All were with the Canon EOS Ra camera and through the SharpStar 76mm triplet apo refractor with the EDPH reducer/flattener for f/4.5. Guiding was with the multi-star Lacerta MGEN3 stand-alone auto-guider, which also controlled the camera shutter and performed dithering between each frame to shift each exposure by a few pixels for noise reduction in stacking. All stacking, alignment and blending was with Photoshop v22.3. Some curves were applied with Lumenzia luminosity masks to selectively adjust the mids or dark-mid tones. Nik Collection ColorEFX ProContrast filter applied locally to the nebulas, plus a high pass sharpening, both to further enhance the nebulosity. No darks or LENR frames were employed or applied on this cool but pleasant and very clear and dry late winter night.
