XMM-Newton Users Handbook



3.5.9.1 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