Analysis of carbon monoxide absorption at z abs 2.5 to constrain variation of the proton-to-electron mass ratio

Absorption by carbon monoxide in the spectrum of quasar SDSS J000015.16+004833.2 is investigated in order to derive a constraint on the temporal variation of the proton-toelectronmass ratio, mu. The spectrum was recorded using Very Large Telescope/Ultraviolet and Visual Echelle Spectrograph, and it was partially corrected for long-range wavelength scale distortions using the supercalibration technique. Eight vibrationalCOsinglet-singlet bands belonging to the A(1)Pi-X-1 Sigma(+) electronic absorption system, and the perturbing d(3) Delta-X-1 Sigma(+)(5, 0) singlet-triplet band are detected in the damped Lyman alpha system at z(abs) similar or equal to 2.52. The spectra are modelled using a comprehensive fitting technique, resulting in a final value of Delta mu/mu = ( 1.8 +/- 2.2(stat) +/- 0.4(syst)) x 10(-5), which is consistent with no variation over a look-back time of similar to 11.2 Gyr.