  Saturated absorption measurements of transitions in the (2-0) band of
radioactive tritium hydride (HT) are performed with the ultra-sensitive
NICE-OHMS intracavity absorption technique in the range 1460-1510 nm. The
hyperfine structure of rovibrational transitions of HT, in contrast to that of
HD, exhibits a single isolated hyperfine component, allowing for the accurate
determination of hyperfineless rovibrational transition frequencies, resulting
in R(0) = $203\,396\,426\,692$ (22) kHz and R(1) = $205\,380 \,033 \,644$ (21)
kHz. This corresponds to an accuracy three orders of magnitude better than
previous measurements in tritiated hydrogen molecules. Observation of an
isolated component in P(1) with reversed signal amplitude contradicts models
for line shapes in HD based on cross-over resonances.
