M17(NGC 6618) Sgr diffuse nebula
Difficulty level 1
The Swan Nebula

Date of observation: 1998/09/20 21:10
Observing site: Hoshinomuara
Transparency/seeing/sky darkness: 3/2/2
Instruments: 32cm Dobsonian with XL14 and OIII filter at 110x
Width of field: 0.6 degrees
This is the famous Swan Nebula and even small apertures can capture this nebula. It is also called the Omega Nebula. Viewing this nebula through the 32cm telescope, I came to understand why it is called the Omega Nebula. With the OIII filter I can imagine the figure of a swan wearing a crown. The brightest part of the nebula is the area from the neck to the body of the swan and the nebulosity is intricately complex. On the head of the swan there is a spot of light and it looks as if it were wearing a crown. At the tip of the beak there are two spots giving an impression that the swan is "sighing." The body narrows toward the tail. On the back there is a faint diffuse area and the swan looks like flapping the wings. A loop structure is faintly seen east of the Swan, and together with another loop at the head, it forms the Greek letter omega. The northern end of the loop looks somewhat brighter. There also seems to be a faint nebulosity north of the Swan, but this was not confirmed as clouds rolled in during the observation.