maged 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. These are the SHO and HOO pallette images generated using the narroband Ha/OIII/SII data (see
https://astrob.in/37u4dg/D/).
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
Starting with individually processed Ha, OIII, and SII images generated the SHO and HOO pallette images using the following steps in PI:
(1) Used the SHO-AIP script to generate the images:
- SHO image (Ha for luminance, R=SII, G=Ha, B=OIII)
- HOO image (Ha for luminance, R=Ha, G=OIII, B=OIII)
(2) 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 = SHO image
Rev B = HOO image
Rev C = starless SHO image
Rev D = starless HOO image
Comments