Blue Pixiedust

Corona Australis

Corona Australis

The southern crown is one of the smallest constellations, but harbors one of the nicest fields in the sky. In the center lies the Coronet Cluster, a small, nearby (400ly) star forming region containing a handful of bright, young stars whose blue light reflect off of the surrounding dusty environment. These dust clouds appear to span the entire image length, 4 degrees. In the far background, about 70 times farther away, lies globular cluster NGC 6723. Its combined light output is 6.8 magnitude, relatively bright and large with angular size 11'. If not for the extinction along the line of sight, NGC 6723 would surely be one of the top 10 brightest globular clusters.

Galaxy ESO 396-16 and a blue anreflection nebula (150% crop)

Galaxy ESO 396-16 and a blue reflection nebula (150% crop). One of the few galaxies visible in this crowded and dusty region. It lies at a distance of 70Mpc, and spans about 2.4'. At magnitude 15.0 it is also quite faint.


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A monkey's face?

A monkey's face?

Accurate image processing requires a good background estimate (which typically varies across the image). Therefore, crowded starfields pose a much greater challenge to handle, especially when they also contain dust over a large portion of the image! In this image, the relatively sharp dust cut-off on the right side near the globular cluster has confused the background correction algorithms, causing a too strong reduction in background locally, which results in the darker falloff next to the globular cluster. Another defect is the artefact near the top bright blue core, caused by clipping of the white balance.

Image information

Globulars, Open clusters, Reflection Nebulae, Tivoli 2016