We present galaxy number-magnitude counts in the range 15 < bj <20.5 from the 4300 square degrees of the APM Galaxy Survey. We have used CCD photometry of 339 galaxies to calibrate the APM magnitudes over a wide range. At bj ∼19-20 our number counts are close to the mean of previously published results. However, our counts show a steep slope between bj=16 and 19 which cannot be explained by local inhomogeneities. Our counts at bj=20.5 are about twice the value predicted by a simple no-evolution model normalized to match the counts at bj≍17. This result implies dramatic evolution of the galaxy population within the past few billion years.
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- November 1990