Spectrum of quasar PKS 1232+0815 with neutral carbon lines at z=2.34

A small part of the spectrum of the distant quasar PKS 1232+0815, as obtained with the UVES spectrograph at the 8.2-m VLT KUEYEN telescope at Paranal. Some carbon absorption lines from an intervening cloud are identified, that are sensitive to the Cosmic Microwave Background Radiation (CMBR).

Technical information about the photo: it is based on observations with the UVES high-dispersion spectrograph at the VLT 8.2-m KUEYEN telescope at Paranal, obtained on April 5 and 7, 2000. It shows a part of the spectrum of the quasar PKS 1232+0815 (V = 18.4; z = 2.57), with the redshifted, ultraviolet absorption lines of neutral carbon in an intervening cloud (z = 2.34). Lines from the same excitation levels are connected. The observed spectrum is fully drawn; the best model fit is indicated with a dashed curve. The wavelength is given in Ångstrom units (1 nm = 10 Å). The slit width was 1 arcsec; the spectral resolution about 45,000 and the integration lasted 3 hours.