Speaker
Description
In recent years Swift/UVOT has taken on a key role in identifying and following up transients. While automated source detection and difference imaging can help in finding transients, these tools cannot distinguish between real transients and star-like image artefacts caused by stray light. Image artefacts such as readout streaks or various ring structures are easy to identify by eye, and we have programs to identify these and flag sources within them. However, during the gravitational wave EM followup searches begun in 2016, we started to identify a small number of star-like features, "ghosts" of bright sources lying within a certain radius of the centre of the field of view. In this poster we will show how we identify these ghosts and how we intend to use the calibration to prevent the follow up of falsely identified new sources.
