  Comet 9P/Tempel 1 was the target of a multi-wavelength worldwide
investigation in 2005. The NASA Deep Impact mission reached the comet on 4.24
July 2005, delivering a 370 kg impactor which hit the comet at 10.3 km/s.
Following this impact, a cloud of gas and dust was excavated from the comet
nucleus. The comet was observed in 2005 prior to and after the impact, at 18-cm
wavelength with the Nan\c{c}ay radio telescope, in the millimetre range with
the IRAM and CSO radio telescopes, and at 557 GHz with the Odin satellite.
  Post-impact observations at IRAM and CSO did not reveal a significant change
of the outgassing rates and relative abundances, with the exception of CH_3OH
which may have been more abundant by up to one order of magnitude in the
ejecta. Most other variations are linked to the intrinsic variability of the
comet. The Odin satellite monitored nearly continuously the H_2O line at 557
GHz during the 38 hours following the impact on the 4th of July, in addition to
weekly monitoring. Once the periodic variations related to the nucleus rotation
are removed, a small increase of outgassing related to the impact is present,
which corresponds to the release of \approx 5000+/-2000 tons of water. Two
other bursts of activity, also observed at other wavelengths, were seen on 23
June and 7 July; they correspond to even larger releases of gas.
