Messier 17 — Emission Nebula in Sagittarius

The Omega Nebula (also called the Swan Nebula, Horseshoe Nebula, or Lobster Nebula) is one of the brightest and most massive star-forming regions in the Milky Way, located about 5,500 light-years away in Sagittarius. The visible nebula is just the bright tip of a much larger molecular cloud containing enough material to form tens of thousands of stars. The nebula spans about 15 light-years and contains an open cluster of about 35 hot young stars whose ultraviolet radiation illuminates the gas.

Located about 2 degrees south of M16 (the Eagle Nebula). One of the most rewarding deep-sky objects for small telescopes. Even a 3-inch telescope at low power reveals the distinctive swan or checkmark shape — a bright bar with a hook at one end. An 8-inch telescope shows extensive nebulosity spreading away from the bright bar, with dark lanes and bright knots. A UHC or OIII filter dramatically enhances the view. Look for the long, graceful curve of the 'swan's neck' extending from the bright bar. Best observed from June through September.

Discovered by Philippe Loys de Cheseaux in 1745-46 and independently by Charles Messier in 1764. The many common names reflect different observers seeing different shapes in the nebula. The open cluster within the nebula was cataloged separately as NGC 6618.