Astronomy Sketch of the Day

M8 – The Lagoon Nebula
Sketch and Details by Kiminori Ikebe

M8 (NGC 6523) Sgr diffuse nebula
Difficulty level 1
The Lagoon Nebula
Date of observation: 1998/05/27 03:20
Transparency/seeing/sky darkness: 3/3/4
Instruments: 32cm Dobsonian with XL21 at 70x and OIII Filter
Width of field: 0.9 degree

Complex structures are visible. There is the open cluster NGC 6530 near the center, which can be seen clearly even with the OIII filter. The brighter part of the nebula is divided into three regions. A triangular-shaped nebulosity in the southwest is the brightest with 9 Sgr (mag 6.1) shining at the center. There is a small, somewhat fainter region south of 9 Sgr. The second brightest region extend from the center to the south, which contains the open cluster NGC 6530. Between the brightest and next brightest regions lies a clear winding dark lane like a large river. The “banks of the river” is bright and a magnificent sight. At the southern end a sharp protrusion like a horn is visible. Although it is faint, the outline is sharp. North of the brightest region lies the third brightest region. It extends from the east to the west and the eastern half is bright providing a fine sight. With a close examination you can detect a faint nebulosity east of NGC 6530. It is large and looks like a very faint mist. In 10×42 binoculars, there are two bright spots side by side in the east-west direction within a narrow triangle. There is a double involving 7 Sgr at the western end of the triangle. There is a star near the center of the western part of the bright region. This star is 9 Sgr and the bright nebulosity surrounding it is clearly seen. The eastern part is rather elongated with the same orientation with NGC 6520. The globular cluster NGC 6544 is clearly seen in the southeast.