2008A&A...490L..31H

The ¹⁶OH/¹⁸OH and OD/OH isotope ratios are measured in the Oort-Cloud comet C/2002 T7 (LINEAR) through ground-based observations of the OH A²Σ⁺ - X²Π_i ultraviolet bands at 3063Å (0, 0) and 3121Å (1, 1) obtained with the Very Large Telescope (VLT) feeding the Ultraviolet-Visual Echelle Spectrograph (UVES). From the ¹⁶OH/¹⁸OH ratio, we find ¹⁶O/¹⁸O=425±55, equal within the uncertainties to the terrestrial value and to the ratio measured in other comets, although marginally smaller. We also estimate OD/OH from which we derive D/H=2.5±0.7x10^–4 in water. This value is compatible with the water D/H ratios evaluated in other comets and is marginally higher than the terrestrial value.