  The different algorithms appropriate for point source photometry on data from
the SPIRE instrument on-board the Herschel Space Observatory, within the
Herschel Interactive Processing Environment (HIPE) are compared. Point source
photometry of a large ensemble of standard calibration stars and dark sky
observations is carried out using the 4 major methods within HIPE:
SUSSEXtractor, DAOphot, the SPIRE Timeline Fitter and simple Aperture
Photometry. Colour corrections and effective beam areas as a function of the
assumed source spectral index are also included to produce a large number of
photometric measurements per individual target, in each of the 3 SPIRE bands
(250, 350, 500um), to examine both the accuracy and repeatability of each of
the 4 algorithms. It is concluded that for flux densities down to the level of
30mJy that the SPIRE Timeline Fitter is the method of choice. However, at least
in the 250 and 350um bands, all 4 methods provide photometric repeatability
better than a few percent down to at approximately 100mJy. The DAOphot method
appears in many cases to have a systematic offset of ~8% in all SPIRE bands
which may be indicative of a sub-optimal aperture correction. In general,
aperture photometry is the least reliable method, i.e. largest scatter between
observations, especially in the longest wavelength band. At the faintest
fluxes, <30mJy, SUSSEXtractor or DAOphot provide a better alternative to the
Timeline Fitter.
