Tasks which compute sky coordinates of events (x-ray or optical photons) which are detected on one of the XMM cameras must take account of the fact that the attitude of the spacecraft (ie its direction of point and its roll angle) are not exactly constant during an exposure. It is of course possible, for each separate event, to obtain the attitude at the time of the event and compute the entire transform to sky coordinates. The attitude wander from one event to the next is however usually not very great, thus computing time can be saved at little expense in accuracy by using the same attitude value for several successive computations. The job of the present task is to generate an attitude time series, with variable bin duration, which has the property that, within any given bin, the attitude does not vary outside preset limits (section 3.2).
The format of the binned attitude file (see section 7 for a description) is accepted by SAS tasks evproject, eootemap, epnoisemap, eimchip2sky and eexpchipmap.