GMOS spectrum of IMS J2204+0111

GMOS spectrum of IMS J2204+0111. A prominent break in the spectrum is visible at the wavelength of about 8500 Å. The feature corresponds to the Hydrogen Lyman-α line which has a wavelength of 1216 Å at rest. It is now shifted to 8500 Å, suggesting that this object is moving away from us at the redshift of 5.944. The sharp break is caused because neutral hydrogen around the quasar absorbed the light at the wavelength below the Lyman-α line.