Sagittarius Specials

The angular extent of Messier 8, the Lagoon Nebula, is ideally suited for CHI-2 or CHI-4, but I haven't been able to observe it with those telescopes. However, while the field of view of CHI-1 captures only part of this nebula, the AUS-2 Takahashi can be used to observe the wider region of sky; and while the plate scale in this case is a bit small, the detector is big enough to allow cropping, permitting a (digital) zoom into the regions of greatest interest.

The crop shown here as the main image is a Hubble-palette rendering. As well as M8, the much smaller Trifid Nebula, M20, can be seen (to the NW; upper right in this frame), along with several less well-known clusters and nebulae, identified in the accompanying annotated full-frame view.

In RGB images, M20 appears as a red nebula embedded in a blue halo. The red light comes from H-alpha gas emission, which shows up clearly in this narrow-band composition. The blue halo, however, results from the light of hot, blue stars scattered off of dust. This scattered starlight barely registers in narrow-band.

An alternative, pseudo-RGB, rendition is included for comparison. Of course, while this palette gives an arguably more 'natural' appearance, it still doesn't emphasize any scattered continuum light.