M8 – The Lagoon Nebula

M8 (NGC 6523) is a large emission nebula found in the constellation of Sagittarius. With a southerly declination of -25° it does not rise very high in UK skies and is best viewed from nearer the equator, from where it may be glimpsed with the naked eye. The open cluster NGC 6530 is embedded in the cloud, and it is these stars that cause the emission nebula to glow.

M8 is about 100 light years long and about 5,000 light years distant. One can only imagine how the night sky would look if it were as close as the Orion nebula, which is only about 1300 light years distant.

This is a narrowband image comprising SII, H-α and OIII filters mapped respectively to the RGB channels. The stars were processed separately to obtain their approximate true colours, as they can otherwise appear purplish through these filters. A Luminance signal was also obtained to improve resolution.

Exposure times were: Lum 8hrs, SII 6hrs, H-α 7 hrs, OIII 8 hrs.

Equipment: Planewave CDK14 corrected Dall-Kirkham telescope, Finger Lakes Instrumentation P9000 CCD camera, Astrodon Luminance and 3nm narrowband filters, Monster Moag off-axis guider with Starlight Xpress Lodestar Pro guide camera.

Acquisition software: ACP Expert Scheduler, Maxim/DL. Image processing: PixInsight.