HerMES: point source catalogues from deep Herschel-SPIRE observations
  We describe the generation of single-band point source catalogues from
submillimetre Herschel-SPIRE observations taken as part of the Science
Demonstration Phase of the Herschel Multi-tiered Extragalactic Survey (HerMES).
Flux densities are found by means of peak-finding and the fitting of a Gaussian
point-response function. With highly-confused images, careful checks must be
made on the completeness and flux density accuracy of the detected sources.
This is done by injecting artificial sources into the images and analysing the
resulting catalogues. Measured flux densities at which 50 per cent of injected
sources result in good detections at (250, 350, 500) {\mu}m range from (11.6,
13.2, 13.1) mJy to (25.7, 27.1, 35.8) mJy, depending on the depth of the
observation (where a `good' detection is taken to be one with positional offset
less than one full-width half-maximum of the point-response function, and with
the measured flux density within a factor of 2 of the flux density of the
injected source). This paper acts as a reference for the 2010 July HerMES
public data release.
