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Molecular hydrogen transitions in quasar spectra can be used to constrain variation in the proton‐to‐electron mass ratio, μ≡  m  p / m  e , at high redshifts ( z  ≳ 2). We present here an analysis of a new spectrum of the quasar Q0528−250, obtained on Very Large Telescope (VLT)/Ultraviolet and Visual Echelle Spectrograph (UVES), and analyse the well‐known H 2  absorber at  z  = 2.811 in this spectrum. For the first time we detect deuterated molecular hydrogen (HD) in this system with a column density of log 10 ( N /cm −2 ) = 13.27 ± 0.07; HD is sensitive to variation in μ, and so we include it in our analysis. Using 76 H 2  and seven HD transitions we constrain variation in μ from the current laboratory value to be Δμ/μ= (0.3 ± 3.2 stat ± 1.9 sys ) × 10 −6 , which is consistent with no cosmological variation in μ, as well as with previous results from other H 2 /HD absorbers. The main sources of systematic uncertainty relate to accurate wavelength calibration of the spectra and the re‐dispersion of multiple telescope exposures on to the one pixel grid.

New constraint on cosmological variation of the proton‐to‐electron mass ratio from Q0528−250