M16 (NGC 6611) Sct diffuse nebula
Difficulty level 3

Date of observation: 1998/09/20 20:51
Observing site: Hoshinomura
Transparency/seeing/sky darkness: 4/2/4
Instruments: 32cm Dobsonian with XL14 and OIII filter at 110x
Width of field: 0.6 degrees
Small telescopes can capture this nebula clearly. As the object is located in a light-polluted part of sky, I used OIII filter. This filter is effective against light pollution and you can see nebulae clearly which are normally invisible without the filter. It looks like a bird with its wings spreading. This shape is somewhat similar to that of M42 and one of the Eagle Nebula in Aquila. Stars concentrate at the head of the nebula forming an open cluster. Four of the stars are strung together providing a fine sight. Behind the open cluster spreads a faint nebulosity. The wing on the south side extends far and narrows toward the end. The wing on the north side is wide and short. A dark lane faintly runs into the center of the nebula from the southeast. This part of the nebula has become famous by a stunning image made by HST.