NGC 7789 area; taken August 15, 2007 from home. Stack of 3 x 4 minute exposures at ISO800 with Canon 20Da and 135mm L-lens at f/2.8. Field equals 7° bino field. Rho Cassiopeiae in field above NGC 7789
This is a complex of faint nebulas and star clusters in Cepheus: While this exposure shows the field as one large nebula, the arc-shaped region at top is catalogued as NGC 7822. The region below with dark lanes through it is Cederblad 214. The loose open cluster at right is NGC 7762, with the small yellowish cluster (dimmed by interstellar dust) is King 11. A small, sparse cluster at the centre of Ced214 is Berkeley 59. The field of view is about 8° by 5.5° with the 250mm focal length RedCat astrograph. This is a stack of 8 x 8-minute exposures through the William Optics RedCat 51mm f/4.9 astrographic refractor with the red-sensitive Canon EOS Ra camera at ISO 800, and blended with a stack of 8 x 15-minute exposures through the Optolong L-Enhance narrowband filter, with the EOS Ra at ISO 3200, to make up for the nearly 3 stops loss of light from the filter. But it really pops out all the faint nebulosity. All images stacked, aligned and blended with Photoshop. Guiding was with the Lacerta MGEN 3 stand-alone autoguider, which also controlled the camera shutter and applied dithering of 10 pixels between each frame to reduce thermal noise without having to apply LENR in camera or dark frames. This was on the Astro-Physics Mach1 mount.
This is the complex of nebulosity that has become known as the Cosmic Question Mark, a good name as its official designations are confusing. The top arc is usually labelled as NGC 7822, and the middle region as Cederblad (Ced) 214. However, some charts and references label Ced214 as NGC 7822, as it is brighter and might have been the object William Herschel saw when amassing observations in the 18th century for his General Catalogue, in which he describes NGC 7822 as "eeF! and eeL!," meaning really really faint and large! The little "dot" of the question mark is the faint and photographic-only nebula Sharpless 2-170, surrounding a little cluster Stock 18 . The field is embedded in dust, indicated by the brownish-yellow tint of the background sky at centre, contrasting with the dust-free bluish starfields at top and bottom. Even the star clusters are yellowed, notably King 11 at top right and NGC 7762 embedded in the nebula at right above the bright star. The loose and sparse cluster Berkeley 59 lies embedded in Ced 214.. Most of the field lies in Cepheus but the lower bits of Ced214 and Sharpless 2-170 lie across the border in Cassiopeia. This is a blend of filtered and unfiltered stacks: 10 x 8-minutes at ISO 3200 through the IDAS NB1 dual narrowband filter, and 10 x 4-minutes at ISO 1600 with no filter, all through the SharpStar 61 EDPHII apo refractor at f/4.6 with its reducer/flattener, and with the red-sensitive Canon Ra, all on the Star Adventurer GTi mount/tracker, autoguided with the Lacerta MGENIII autoguider, taken as part of testing the mount. No darks or LENR applied here, but the autoguider applied some dithering offset between each frame, to largely cancel out thermal noise hot pixels when the sub-frames were aligned and stacked. Taken Sept. 21/22, 2022 from home in Alberta on a very clear cool night. Shooting and then blending filtered with unfiltered shots provides the best of both worlds: lots of reddish nebulosity set in a sky with natural coloured stars and background tints. I applied a slight level of star reduction with a "starless" layer created with RCAstro Star XTerminator, but with only 25% opacity to just reduce but not eliminate stars. In fact, StarX did a poor job eliminating all the stars in this image. But Noise XTerminator did a great on reducing fine-scale noise. Nebulosity was brought out with DM1, DM2 and colour-range luminosity masks created with Lumenzia plug-in panel for Photoshop. Finishing touches with a High Pass Sharpen layer and a Paint Contrast layer (the latter added with TK Actions panel) boosted fine-scale contrast to the nebulosity. All stacking, aligning and blending done in Adobe Photoshop. A footnote: This has traditionally been a target that has always given me trouble with technical issues or some other problem often spoiling the images. As it was, some guiding errors from the mount mistracking marred a number of frames, but a selection were good enough to use for this stacking set. The result was my best take on this target.
