The Hubble deep fields

The Hubble space telescope observations of the northern Hubble deep field, and more recently its counterpart in the south, provide detections and photometry for stars and held galaxies to the faintest levels currently achievable, reaching magnitudes V similar to 30. Since 1995, the northern Hubble deep field has been the focus of deep surveys at nearly all wavelengths. These observations have revealed many properties of high redshift galaxies and have contributed to important data on the stellar mass function in the Galactic halo.