The Messier star cluster M35 at top right, along with nearby faint nebulas: IC 443, the arc of nebulosity left of centre, and NGC 2174 at bottom right, all set in a very colourful starfield. IC 443 in Gemini is also known as the Jellyfish Nebula, while NGC 2174 in Orion is aka the Monkeyhead Nebula. IC 443 is a supernova remnant, while NGC 2174 is a star forming region. The images for this stack were taken on a less-than-ideal night with high haze adding the natural glows to the stars, accentuating their colours. The two stars at left, Tejat Posterior (aka Mu Geminorum, left) and Propus (aka Eta Geminorum, centre), are both bright red giant stars. Other stars in the field are hot blue stars. This is a stack and blend of: 10 x 4-minute exposures through an Astronomik CLS clip-in filter blended with 8 x 8-minute exposures taken though a 12nm H-Alpha clip-in filter to add in the red nebulosity. All were through the SharpStar 61mm EDPHII apo refractor at f/4.5 and with the Canon EOS Ra camera at ISO 1600 for the CLS filtered images and at ISO 3200 for the H-Alpha filtered shots. Taken from home for a demo image, on a hazy night, March 29, 2022, with the MGEN III autoguider performing inter-frame dithering. It serves as a demo of blending in H-Alpha and also making use of a hazy night! Processing details: The H-Alpha shots were converted to monochrome and processed in Adobe Camera Raw, and blended into the colour image stack with a Lighten blend mode and with colorization added using the Debra Ceravolo method of applying a Hue&Saturation layer set to Colorize at 340 Red and a Lightness of ~50. Masking was applied so the H-alpha image shows through only where the nebulosity is, to prevent the overall sky colour turning red. No darks or flats were applied. All aligned, stacked and blended in Photoshop. Framing planned with SkySafari to include the stars at left and right of the frame.
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.
