Faint galaxy surveys.

Various K band galaxy surveys have now established 2.2-m galaxy counts from K = 10 to K = 23. The K band counts rise slightly faster than a Euclidean slope to K = 17, at which point they turn over; beyond this magnitude, galaxies also become much bluer. Spectroscopic samples are available between K = 10 and 20 and show that the conventional distance laws hold rather precisely out to a redshift of about 0.6. Beyond this, galaxies appear fainter than expected. The results appear to favor rapid merging at modest galactic redshifts.