M17 (NGC 6618)

The diffuse nebula M17 (NGC 6618) goes by a number of names. Most often these days it's The Omega Nebula, but it is also known as The Swan Nebula, and even The Horseshoe Nebula. In the Southern Hemisphere it's The Lobster Nebula.

With an apparent magnitude of about 6.0, it's nearly a naked-eye object. While visible in binoculars, it requires a large telescope to fully appreciate.

M17 is easily found by binoculars, starting with M24. North 2 is M18, a small and undistinguished cluster, and one degree further north is the Omega Nebula: binoculars.

The nebula has been the site of star formation and either this is continuing or it has ceased quite recently (i.e. several million years ago?). It's the baby stars which provide the reddish background glow.


Moving five full binocular fields east brings you to the last item in Sagittarius we will examine, the binary 54 Sagittarii. It's also six fields due south of Altair (alpha Aquilae).

54 Sagittarii is a multiple system of which component C is the most accessible:
      54 Sgr (h599)AC: 5.4, 7.7; 42, 45.3".

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1999-2014 by Richard Dibon-Smith.