The APM Galaxy Survey contains positions, magnitudes, sizes and shapes for about 3 million galaxies selected from 269 UKST survey plates which were scanned using the APM Facility .
The galaxies have apparent magnitudes with 17 < b_j < 20.5 and are spread through the largest volume of the universe that has been surveyed to date. The picture shows the galaxy distribution as a density map in equal area projection on the sky, centered on the South Galactic pole.
Each pixel covers a small patch of sky 0.1 degrees on a side, and is shaded according to the number of galaxies within the area: where there are more galaxies, the pixels are brighter. Galaxy clusters, containing hundreds of galaxies closely packed together, are seen as small bright patches. The larger elongated bright areas are superclusters and filaments. These surround darker voids where there are fewer galaxies.
The colours are coded according to the apparent magnitude of the galaxies in each pixel: fainter galaxies are shown as red, intermediate are shown as green and bright are show as blue. The more distant galaxies tend to be fainter, and also show less clustering, and so the maps has a generally uniform reddish background. The more nearby galaxies tend to be bright, and are more clustered, so the more prominent clusters of galaxies in the map tend to show up as blue.
The small empty patches in the map are regions that we have excluded around bright stars, nearby dwarf galaxies, globular clusters and step wedges.
C'est là où il n y a rien d'intéressant, si j'ai bien compris
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„Ich kann, weil ich will, was ich muss.“ I. Kant