The California Nebula (NGC 1499) is an emission nebula spanning over 100 light-years in the constellation Perseus, located approximately 1,000 light-years from Earth. Its elongated shape and glowing hydrogen gas resemble the outline of the U.S. state of California. The nebula is primarily ionized by the nearby hot, massive star Xi Persei, whose intense ultraviolet radiation excites the surrounding hydrogen, producing its characteristic red glow in visible light. This deep capture in the SHOLRGB palette enhances the intricate structures of ionized sulfur (SII), hydrogen (Ha), and oxygen (OIII), revealing subtle variations in gas composition and dynamics.

With a total integration time of 54 hours and 42 minutes, this image showcases an extraordinary depth, capturing delicate filaments and extended faint structures that are often lost in shorter exposures. The high signal-to-noise ratio allows for an intricate balance of narrowband and broadband data, preserving both the detailed ionization fronts and the rich stellar background. The result is a highly detailed and scientifically revealing view of one of the sky’s most well-known emission nebulae.