This target is such a cool target to me – the question mark top is already incredibly interesting, and the little dot below is icing on the cake. NGC 7762 is the big curvy part of the question mark, and SH2-170 is the little dot at the bottom. This target is so big that I actually had to do a two panel mosaic! All the red in this image is caused by hydrogen gas being ionized by the large stars near it, causing the gas to glow red.
Image:
Equipment:
- Nikon D90
- Sigma 300mm prime lens
- Sky-Watcher Star Adventurer
- Star Adventurer Tripod
- Bahintov Mask
- Intervalometer
- Stellarium
- All Sky Plate Solver
- Sharpcap
- Laptop
Acquisition:
- Bortle 2-4
- ISO 800
- F/4.0
- Sharon, CT
- North Panel
- Taken on 8/22/2021
- 127 x 3′ light frames (total 6.32 hours)
- 200 bias frames
- 50 flat
- 22 dark
- South Panel
- Taken on 8/24/2021
- 131 x 3′ light frames ( total 6.55 hours)
- 23 dark
- 51 flat
Processing:
- Calibrate subframes with WBPP
- Blink to get rid of bad frames
- Stacked with normalize scale gradient
- Combined panels with Photometric mosiac
- Downsample 2x
- DBE
- Extract Lum
RGB processing:
- EZ denoise
- masked stretch
- histogram stretch
Lum processing:
- EZ denoise
- Slight deconvolution
- Masked stretch
- Histogram stretch
- Combine with a straight average
Non-linear processing:
- LRGB combination with Chrome denoise
- Multiscale processing with MMT, curves, and colorsaturation
- Star reduction
- Curves transformation
Annotated image:
