Wikipedia-

The California Nebula (NGC 1499/Sh2-220) is an emission nebula located in the constellation Perseus. Its name comes from its resemblance to the outline of the US State of California in long exposure photographs. It is almost 2.5° long on the sky and, because of its very low surface brightness, it is extremely difficult to observe visually. It can be observed with a Ha filter (isolates the Ha line at 656 nm) or Hß filter (isolates the Hß line at 486 nm) in a rich-field telescope under dark skies. It lies at a distance of about 1,000 light years from Earth. Its fluorescence is due to excitation of the Hß line in the nebula by the nearby prodigiously energetic O7 star, Xi Persei (also known as Menkib). The California Nebula was discovered by E. E. Barnard in 1884.

  This is a first light image using the new Player One Poseidon-M Pro camera (Sony IMX571) w/ Antila SHO Pro narrow band filters and the Askar FRA400 astrograph.

 

Location & Date	Backyard, Abbott Observatory- Long Island, NY,  December 15&18 2023
Telescope	Askar FRA400 F/5.6 Quintuplet Petzval Astrograph, ZWO focuser, iOptron GEM45G mount Image scale 1.93 arcsec/pixel
Camera	Player One Poseidon-M Pro Antlia  Ha (4.5nm) & SII OIII 3nm Pro filters Sensor temp -15°C
Exposures	Ha-18x5m SII-18x5m OIII-35x5m Bin 1x1  Gain=0 Offset=20
Planning & Acquisition	Sequence Generator Pro
Processing	Astro Pixel Processor - calibration, stacking Photoshop  2024- Ha SIi OIII combine using a modified Hubble Palette RC-Astro- Star XTerminator, Noise Xterminator

Initial stretch of 1 1/2 hours of Hydrogen Alpha (Ha) taken with Antlia 4.5nm filter

Initial stretch of 1 1/2 hours of Sulfur (SII) taken with Antlia 3nm filter

Initial stretch of 2.9 hours of Oxygen (OIII) taken with Antlia 3nm filter

The OIII has low brightness but the 3nm filter enhances the contrast