Finding, identifying & following-up X-ray transients

XMM-Newton has been flying for more than 21 years and has made almost a million X-ray detections. Amongst these
objects, many are rare types of compact object systems, often identified through their strong variability, some times
thanks to the long baseline over which a source can be observed. Here we present some of the transients discovered in the XMM-
Newton catalogues, produced by the XMM-Newton Survey Science Centre (XMM-SSC) and describe software that is being put into
place to detect, identify and communicate serendipitous transients in quasi-real time, to allow them to be followed-up rapidly.