Colour corrections for high-redshift objects due to intergalactic attenuation

Corrections to the magnitudes of high-redshift objects due to intergalactic attenuation are computed using current estimates of the properties of the intergalactic medium (IGM). The results of numerical simulations are used to estimate the contributions to resonant scattering from the higher-order Lyman transitions. Differences of 0.5-1 mag from the previous estimate of Madau are found. Intergalactic k_IGM-corrections and colours are provided for high-redshift starburst galaxies and Type I and Type II quasi-stellar objects for several filter systems used in current and planned deep optical and infrared surveys.