XMM-Newton RPS Users Manual

3.1.2.3 For a bright point source

7.

Science mode of all instruments

For each of the MOS and pn, it must be decided if the source is bright enough to give rise to photon pile-up that would degrade the calibration beyond that demanded by the science goals when using the ``Full Frame'' imaging mode (see UHB section on EPIC pile-up ). In the case of a bright point source, pile-up is likely to be a concern. Then the user should choose the partial window mode with the largest FOV that minimises pile-up or, for the very brightest sources, use the ``Timing'' mode.

In order to assess possible pile-up in individual emission lines in RGS data of bright targets, SciSim should be used for modeling the source spectrum; in the case where photon pile-up is not a problem, the RGS should (for standard spectroscopy) be left in the normal ``Spectroscopy'' mode. If a high ($>70$counts/s) count rate is expected, the ``Spectroscopy HCR'' (HCR = High Count Rate) mode should be used (see UHB section 3.4.5 on RGS modes ).

For an optically bright point source the user might consider using the OM's ``Image Fast'' mode, if high time-resolution photometry is required. For each of the science instruments, there is one ``Image Fast'' mode configuration, corresponding to the instrument being prime.

8.

Length of observation

If the observation is long compared with the visibility window (as reported by the online XMM-Newton Target Visibility Tool), the user must consider how best to split it up, e.g., into multiple observations that fit into continuous visibility periods.

9.

Selection of EPIC optical blocking filter

Users must check the visible magnitude of in-field or nearby optical sources and the science target itself. If the soft X-ray response is important, one should choose the thinnest filter compatible with the brightest visible objects, as described in the UHB section on EPIC filters .

10.

RGS readout sequence

In case of ``Spectroscopy HCR'' mode observations of a target with particularly strong emission lines, observers might want to read out individual CCDs more often than others (see § 5.2.4.4).

11.

Choice of OM filter sequence

For the OM it must be decided if specific filter coverage is necessary to achieve the science or if the recommended filter sequence is adequate (see UHB section on OM modes ).

12.

Length of exposures

Telemetry and onboard memory limits place upper and lower boundaries on the duration of single OM exposures as listed in § 5.2.4.5.