XMM-Newton Phase II RPS Users Manual

3.1.1 General considerations

1. Choice of prime instrument

   Users must first decide which is the main science goal and with which of the XMM-Newton science instruments this goal can be best achieved. We recall, that all XMM-Newton scientific instruments operate simultaneously.

2. Science mode of prime instrument

   Next, the best-suited instrument mode with which to conduct the observations, depending on the target properties, must be chosen. More on this will follow in § 3.1.2, immediately below.

3. Integration time

   It must be decided how much integration time is needed for the prime instrument, operated in the selected mode, to achieve the science goals. Users must note that at this stage, the integration time has already been fixed by the OTAC and hence this is the time that should be used in the form.

4. Pointing direction

   For extended targets the optimal pointing direction (which might not coincide with the catalogued target coordinates) must be chosen. The pointing should be chosen in such a way that the target is optimally located on the detector of the prime instrument. Thus, if there is a certain region, e.g., in an extended target that is of particular interest, the coordinates of that particular point should be chosen as the boresight coordinates.

5. Avoidance of nearby sources

   XMM-Newton science data (both X-ray and optical/UV) can be contaminated by radiation from nearby sources. If such is the case and wants to be avoided, this might, e.g., lead to position angle constraints on the observations (for example in order to prevent spectral overlaps) which must be considered.

   Users must check for the presence of bright optical/UV sources in the OM FOV. In the case that a source violates the OM brightness limits, which are listed in the UHB Table 25 , OM can not be used for observing the target. This time will be used by the SOC for calibration observations with Filter = BLOCKED. Take notice that the OM brightness limit is filter depedent.

6. Observations and exposures

   An XMM-Newton proposal can consist of up to 50 observations. An ''observation'' is defined as a pointing to one particular position on the sky, including all sub-units of the observations, which are called ''exposures''. For example, a second pointing towards a slightly offset position compared to the first observation (because, e.g., the target does not fit into the EPIC field of view) is a second, independent observation. Pointing towards a new target or position is, by definition, always a new observation since XMM-Newton has no capability to perform raster scans.