Imaged the California Nebula (NGC 1499) using dual narrowband filters on the nights of January 7/8, 2022 in Ha/OIII and February 5/8/9/10, 2022 in SII/OIII.
Imaged with Astrotech AT60 at F4.8 (288 mm focal length) using Astrotech ATRF60 field flattener/0.8x reducer, Optolong L-Enhance dual narrowband filter (for Ha and OIII) and IDAS NB3 dual narrowband filter (for SII & OIII), and full spectrum modified Nikon D5300. Imaging controlled using an ASIAir Plus with focus via EAF.
Total integration time of ~7.5 hours for each filter:
Ha/OIII: 94 subs at ISO400 x 300 sec
SII/OIII: 91 subs at ISO400 x 300 sec
Pre/post-processing in PixInsight. Images calibrated using Weighted Batch Pre-Processing (BPP) script using darks, flats, and flat darks. Extracted R/B/G channels and processed R (Ha) and G+B (OIII) channels separately. Registered and stacked using StarAlighment and Integration processes. Post-processing steps included: Cropped, gradient removal with ABE and noise reduction using MLT, masked stretch, curves transformation, HDR transformation, local histogram transformation, and morphological transformation.
Original version = Ha image
Rev B = OIII image
Rev C = SII image
Rev D = Ha image, preprocessed using Generalized Hyperbolic Stretch script. Saw this on the Astrobin 'latest from the forums' list and gave it a try. Works really nicely. See:
https://ghsastro.co.uk
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