Edit 9/10/2021: This image was selected for Italy’s APOD GRAG: https://apod.grag.org/2021/09/10/a-sagittarius-triplet-m8-m20-and-ngc-6559/
This so far is my favorite image! Nearly 21 hours of data (taken across 4! nights) and 3 hours of processing went into this huge project. I love the color range so much – golden milky way stars, pink lagoon nebula, and light blue trifid reflection.
Image:
Equipment:
- Nikon D90
- Sigma 300mm prime lens
- Sky-Watcher Star Adventurer
- Star Adventurer Tripod
- Bahintov Mask
- Intervalometer
- DIY diffraction spikes using a violin strings
- Stellarium
- All Sky Plate Solver
- Sharpcap
- Laptop
Acquisition:
- Bortle 2-4
- ISO 800
- F/4.0
- Sharon, CT
- 8/7/2021
- 112 x 3′ lights
- 200 bias
- 50 flats
- 32 darks
- 8/8/2021
- 92 x 3′ lights
- 50 flats
- 12 darks
- 8/11/2021
- 102 x 3′ lights
- 50 flats
- 16 darks
- 8/14/2021
- 108 x 3′ lights
- 100 bias
- 50 flats
- 27 darks
- Total:
- 414 x 3′ lights (20.7 hours)
- 300 bias
- 200 flats
- 87 darks
Processing:
- Calibrate using WBPP
- Assign weights with subframe selector
- Star align
- Integrate 10 best images for a local norm reference
- ABE degree 1 on the image
- Local norm scale 256
- Image integration
- CFA drizzle
- DBE
- Background neutralization
- PCC
- Extract L
- Histogram transformation and ArcsinH stretch on RGB
- Masked stretch and Histogram stretch on Luminance data
- LRGB combine
- create starless image
- Exponential transformation on starless image
- Blend back to LRGB with pixel math to avoid blowing out stars
- Slight curves
- Adam block style star reduction
- blend back using straight average with normal image
- Annotate image with watermark
Annotated Image:
