XMM-Newton Phase II RPS Users Manual

3.1 Planning an XMM-Newton observation

The Principal Investigator (PI) of an XMM-Newton proposal must be aware of those issues which irretrievably corrupt the data taken in-orbit and transmitted to ground and must plan and prepare their observations accordingly. Corruption of scientific results can, e.g., take the form of:

• confusion, or mixing, of the source photons with those from another source in, or near, the field of view,

• corruption of the reported energy data due to pile-up of more than one photon per pixel per CCD readout frame or due to excessive optical loading of the X-ray CCDs,

• loss of information due to saturation of telemetry rates,

• loss of calibration accuracy due to photons lost at CCD chip edges.

Generally, the observer needs to consider only the target of interest from the point of view of a simple matrix of properties, namely, is the source bright or faint, is one interested primarily in spatial, spectral or temporal information and whether the target is extended or point-like.

For each type of XMM-Newton instrument (EPIC, RGS, OM) the user must consider the optimal choice of instrument setup to maximise the scientific return of the observation. General preparatory steps to be taken are:

1. as a minimum, calculate the expected count rates using the information contained in the XMM-Newton Users Handbook or the PIMMS (Portable Interactive Multi-Mission Simulator) software from the Goddard Space Flight Center, at the URL:
   http://heasarc.gsfc.nasa.gov/Tools/w3pimms.html

2. using optical source catalogues, determine the brightest optical object in the field of view; if any source beyond the OM brightness limit should be in its field of view (FOV), no OM exposures should be defined.

3. using X-ray source catalogues, determine the presence of nearby X-ray bright objects which may cause straylight degradation.

4. using the XMM-Newton Target Visibility Tool, determine the maximum duration of continuous visibility available in any orbit.

5. use information from the XMM-Newton Serendipitous Source Catalogue or the XMM-Newton Science Archive XSA of previous observations of the target of interest if available.

We will now describe -- in the form of checklists -- which aspects of an XMM-Newton observation must be considered when planning an observation for different kinds of targets. Appendix A contains examples for the possible choices for some crucial input parameters, depending on the target properties. An example for how to prepare the XRPS form sheets based on such considerations and parameter choices is presented in § 3.2.