  The search for the electromagnetic counterparts to gravitational wave (GW)
events has been rapidly gathering pace in recent years thanks to the increasing
number and capabilities of both gravitational wave detectors and wide field
survey telescopes. Difficulties remain, however, in detecting these
counterparts due to their inherent scarcity, faintness and rapidly evolving
nature. To find these counterparts, it is important that one optimises the
observing strategy for their recovery. This can be difficult due to the large
number of potential variables at play. Such follow-up campaigns are also
capable of detecting hundreds or potentially thousands of unrelated transients,
particularly for GW events with poor localisation. Even if the observations are
capable of detecting a counterpart, finding it among the numerous contaminants
can prove challenging. Here we present the Gravitational wave Electromagnetic
RecovRY code (GERry) to perform detailed analysis and survey-agnostic
quantification of observing campaigns attempting to recover electromagnetic
counterparts. GERry considers the campaign's spatial, temporal and wavelength
coverage, in addition to Galactic extinction and the expected counterpart light
curve evolution from the GW 3D localisation volume. It returns quantified
statistics that can be used to: determine the probability of having detected
the counterpart, identify the most promising sources, and assess and refine
strategy. Here we demonstrate the code to look at the performance and parameter
space probed by current and upcoming wide-field surveys such as GOTO & VRO.
