IC 4604 is a reflection nebula surrounding the multiple star system Rho Ophiuchi, near the Antares region on the Ophiuchus/Scorpius border.
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IC 4604 is a reflection nebula surrounding the multiple star system Rho Ophiuchi, near the Antares region on the Ophiuchus/Scorpius border. It forms part of the larger Rho Ophiuchi cloud complex (also including IC 4603, IC 4605, and the dusty nebulosity around Antares itself), one of the closest active star-forming regions to the Sun, with distance estimates generally in the range of about 400-560 light-years. The region is prized by astrophotographers for its striking color palette: blue reflection nebulosity around Rho Ophiuchi, yellow-brown dust clouds, and the reddish glow associated with nearby Antares, all threaded with dark Barnard dust lanes. Because the nebulosity is faint and covers a wide field (roughly 4.5 by 6.5 degrees), it favors wide-field broadband imaging from a dark sky site over narrowband techniques.
[Source: general astronomical references, incl. deepskycorner.ch and Wikipedia Rho Ophiuchi cloud complex]
