  GRB 090423 is the most distant spectroscopically-confirmed source observed in
the universe. Using observations at 37.5 GHz, we place constraints on molecular
gas emission in the CO(3-2) line from its host galaxy and immediate environs.
The source was not detected either in line emission or in the rest-frame 850
micron continuum, yielding an upper limit of S_{8mm}=9.3 milli-Jy and
M(H_2)<4.3x10^9 M_sun (3 sigma), applying standard conversions. This implies
that the host galaxy of GRB 090423 did not possess a large reservoir of warm
molecular gas but was rather modest either in star formation rate or in mass.
It suggests that this was not an extreme starburst, and hence that gamma ray
bursts at high redshift trace relatively modest star formation rates, in
keeping with the behaviour seen at lower redshifts. We do, however, identify a
millimetre emission line source in the field of GRB 090423. Plausible
interpretations include a CO(1-0) emitting galaxy at z=2.1, CO(2-1) at z=5.2
and CO(3-2) at z=8.3. Efforts to identify a counterpart for the molecular line
emitter and to further characterise this source are continuing.
