XMM-Newton Users Handbook OM operating modes

The OM can operate in the two modes listed in Table 26. These allow either imaging or fast photometry or both simultaneously.

Table 26: The science data acquisition modes of OM
Mode$^1$ Special feature
Imaging Mosaic of 2-D imaging windows with long exposure times ($>800$ s)
Fast High time resolution, providing 2-D time-sliced images over small areas.
Notes to Table 26:
1) Both modes can be used simultaneously, as long as total memory capacity and telemetry bandwidth are not exceeded.

Each mode has a specific overhead, i.e., time needed for the instrument set-up, before the actual science exposure can start. For both the above OM modes this overhead includes also the reference frame exposure. In addition, about 1000 s are needed before starting the OM exposures for the field acquisition of the satellite star tracker. The reader is referred to § 4.5.2 for a general discussion of the impact of instrumental overheads on the planning of an XMM-Newton observation, and to the XRPS User's Manual for a detailed description of the OM overheads. An interactive web tool is available at the MSSL web page:
https://www.mssl.ucl.ac.uk/www_astro/xmm/om/om_tool_current.html, which may help the user to better handle and understand OM windows and operational overheads.

European Space Agency - XMM-Newton Science Operations Centre