Imaged the Orion Nebula (M42) using dual narrowband filters on the nights of December 19/22, 2021 and January 26/29, 2022 in Ha/OIII and February 5/9/10/11, 2022 in SII/OIII. These are the HOO and HOS palette images generated using the narrowband Ha/OIII/SII data (see
https://astrob.in/x4kis4/0/).
Imaged with Astrotech AT60 at F/4.8 (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 ~8 hours in Ha/OIII and ~6 hours in SII/OIII:
Ha/OIII: 99 subs at ISO400 x 300 sec
SII/OIII: 77 subs at ISO400 x 300 sec
Starting with individually processed Ha, OIII, and SII images generated the SHO (Hubble Space Telescope palette), HOO, and HOS (Canada-France-Hawaii Telescope palette) palette images using the following steps in PI:
(1) Used the SHO-AIP script to generate the images:
> SHO image (Ha/OIII/SII for luminance, R=SII, G=Ha, B=OIII)
> HOO image (Ha/OIII/SII for luminance, R=Ha, G=OIII, B=OIII)
> HOS image (Ha/OIII/SII for luminance, R=Ha, G=OIII, B=SII)
(2) For the SHO and HOS images, reduced the magenta tone of the stars using the following steps: Inverted image, applied SCRN process (set to Green), inverted image again.
(3) Tweaked the color palette from green dominated to more orange dominated by first using Curves Transformation in Hue mode followed by SCNR to remove green.
(4) Color saturation boost
(5) Used Starnet2 process to generate starless versions
Original version = HOO image
Rev B = starless HOO image
Rev C = HOS image
Rev D = starless HOS image
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