  Polarimetric studies of astrophysical sources can make important
contributions to resolve the geometry of the emitting region and determine the
photon emission mechanism. PoGOLite is a balloon-borne polarimeter operating in
the hard X-ray band (25-240 keV), with a Pathfinder mission focussing on Crab
observations. Within the polarimeter, the distribution of Compton scattering
angles is used to determine the polarisation fraction and angle of incident
photons. To assure an unbiased measurement of the polarisation during a balloon
flight it is crucial to characterise the performance of the instrument before
the launch. This paper presents the results of the PoGOLite calibration tests
and simulations performed before the 2013 balloon flight. The tests performed
confirm that the polarimeter does not have any intrinsic asymmetries and
therefore does not induce bias into the measurements. Generally, good agreement
is found between results from test data and simulations which allows the
polarimeter performance to be estimated for Crab observations.

Instrumentation and Methods for Astrophysics;Instrumentation and Detectors