XMM RPS Users' Manual

   
Filling in EPIC pn details

In Fig. 13 a screen shot of an EPIC pn exposure formsheet is displayed.

  

Figure 13: Screen shot of an EPIC pn exposure form sheet. Mode PRI FULL PN, in conjunction with Frame Time Parameter = 5, defines the FULL WINDOW EXTENDED mode, which has a longer live time and less out-of-time events (see UHB section on points of concern ) than the normal FULL WINDOW mode, but potentially higher pile-up rates.

The selectable parameters for the pn camera are again the EPIC filters , exposure time, exposure offset (which should normally be 0) and the EPIC modes .

Optical blocking filters

The choice of optical blocking filters is the same as for EPIC MOS (see Tab. 1, in § 5.3.3.1).

pn modes of operation

The descriptions of the EPIC modes in the UHB and XRPS differ because of the changes that the modes and their names have undergone with time. The way the UHB and XRPS names map onto each other is described in Tab. 3.

The UHB modes TIMING and BURST are two flavours of the EPIC fast mode, where the BURST mode has an extremely short duty cycle. Both modes operate on one CCD (the one on which the nominal on-axis boresight falls).

 

Table 3: Mapping of EPIC pn mode names

UHB name	XRPS name1
FULL WINDOW (400$\times$384)	PRI FULL PN3
FULL WINDOW EXTENDED2	PRI FULL PN4
LARGE PARTIAL WINDOW (200$\times$256)	PRI LGE WIN
SMALL PARTIAL WINDOW (64$\times$64)	PRI SML WIN
TIMING	FAST TIMING
BURST	FAST BURST

Notes to Table 3:
1) During AO-1 only the highlighted modes are recommended for use.
2) ``Extended'' means that the image collection time is extended by a programmable parameter (not user-selectable).
3) With ``frame time parameter'' value 0.
4) With ``frame time parameter'' value 5.

Frame time parameter

The XRPS mode PRI FULL PN comes in two flavours, depending on the frame time parameter. A frame time parameter of 0 represents the default imaging mode. A value of 5 extends the frame readout time by a factor of 5, thereby reducing the percentage of so-called ``out of time events'' (i.e., photons registered while the CCD is being read out). The ``FULL WINDOW EXTENDED'' mode of pn (i.e., ``PRI FULL PN'' with frame time parameter = 5) should be used in particular for relatively faint extended sources, see the UHB section on points of concern . Currently only the values 0 and 5 are allowed.

Exposure offset

This should be 0 again in order to avoid times during which the instrument is idle.

pn camera unit

There is only one EPIC pn camera, therefore the instrument unit is not a selectable parameter.