Fully clear nights are still hard to find in this Ohio spring, although I have finally been able to begin a new imaging project. In the meantime, to keep my processing skills fresh, I decided to tackle another one of my favorite images that I have done, Abell 2151, the Hercules Galaxy Cluster.
I was able to fine tune the way I use the different neural-network based processes to decrease artifacts in the stars as well as the stars presence while enhancing the detail of the image quite a bit, bringing out remarkable structure in these very faint and distant galaxies.
Abell 2151 is a cluster of around 200 galaxies in the constellation Hercules. There are old elliptical galaxies interspersed with spiral galaxies. Many galactic mergers and interactions are also visible in the image. The galaxies in this cluster are mostly between 400 and 700 million light years away. Below are two mosaic images containing crops of some of the more interesting members of this cluster,
The full field,
From the NGC, IC, and PGC catalogues, this image contains 227 annotated galaxies.
And annotating with Milliquas, the Million Quasars Catalog, reveals 82 quasars. The following image labels these with with redshift z and r-band magnitude when available. The limiting magnitude of this image seems to be around 21.25.
The most redshifted quasar visible in this image is SDSS J160622.30+174805.5, and it has taken the record now as the most distant object I have imaged that I know of. This object has a redshift z = 3.87901 +/- 0.00031 and a z-band magnitude of 18.323 +/- 0.034. Assuming a flat universe, this means that this quasar had a light travel time of 12.104 billion years and a comoving radial distance of 23.585 billion light years, or how far the galaxy would be from us now. The heliocentric velocity, the speed at which the quasar was receding away from us when the light that hit my telescope left it, was 1,162,899 km/s, or about 3.87 times the speed of light.
