JINGLE, a JCMT legacy survey of dust and gas for galaxy evolution
  studies: II. SCUBA-2 850 {\mu}m data reduction and dust flux density
  catalogues
  We present the SCUBA-2 850 ${\mu}m$ component of JINGLE, the new JCMT large
survey for dust and gas in nearby galaxies, which with 193 galaxies is the
largest targeted survey of nearby galaxies at 850 ${\mu}m$. We provide details
of our SCUBA-2 data reduction pipeline, optimised for slightly extended
sources, and including a calibration model adjusted to match conventions used
in other far-infrared data. We measure total integrated fluxes for the entire
JINGLE sample in 10 infrared/submillimetre bands, including all WISE,
Herschel-PACS, Herschel-SPIRE and SCUBA-2 850 ${\mu}m$ maps, statistically
accounting for the contamination by CO(J=3-2) in the 850 ${\mu}m$ band. Of our
initial sample of 193 galaxies, 191 are detected at 250 ${\mu}m$ with a $\geq$
5${\sigma}$ significance. In the SCUBA-2 850 ${\mu}m$ band we detect 126
galaxies with $\geq$ 3${\sigma}$ significance. The distribution of the JINGLE
galaxies in far-infrared/sub-millimetre colour-colour plots reveals that the
sample is not well fit by single modified-blackbody models that assume a single
dust-emissivity index $(\beta)$. Instead, our new 850 ${\mu}m$ data suggest
either that a large fraction of our objects require $\beta < 1.5$, or that a
model allowing for an excess of sub-mm emission (e.g., a broken dust emissivity
law, or a very cold dust component 10 K) is required. We provide relations to
convert far-infrared colours to dust temperature and $\beta$ for JINGLE-like
galaxies. For JINGLE the FIR colours correlate more strongly with
star-formation rate surface-density rather than the stellar surface-density,
suggesting heating of dust is greater due to younger rather than older
stellar-populations, consistent with the low proportion of early-type galaxies
in the sample.
