XMM RPS Users' Manual

   
Filling in OM exposure settings

For the OM a number of details must be specified, if non-default configuration observations should be carried out. These can be defined on a special page by pressing the ``Add Details'' button at the bottom of the exposure page. The appropriate formsheet is displayed in Figs. 16.

  

Figure 16: Screen shot of an OM exposure details page. Entries for one science window have already been committed to memory; those for a second window are still in the input fields. Committal of these will add a second entry in the upper part of the form.

OM science mode

First the science mode for each window defined must be chosen. The choice for non-default OM observations is limited to ``IMAGING'', ``FAST'' and ``GO-OFF'' (see Tab. 5).

OM science window coordinates

There are two columns of input fields, only one of which must be filled in. The left column asks for sky coordinates and a window size in angular units. The default coordinates for the centre of an OM science window are the boresight coordinates defined above at the observation level. The window size (DX,DY), in units of arcmin, is limited to 0'-17'. The complex boundary conditions that apply to non-default non-default OM science windows are described in the UHB. The right column requires inputs in detector coordinates (pixels). Upon committal of a set of entries defining a science window the top part of the window in Fig. 16 is filled automatically. For the OM up to 5 science windows may be defined in total, of which up to 2 may be operated in the fast mode.

DPU binning

In the lower part of the OM exposure settings page only the pixel binning in the Digital Processing Unit (DPU) must be specified. The choice is between values from 0 to 2. They stand for the power of 2. Value 0 represents 2⁰ = 1 pixels, 2¹ = 2 and 2² = 4. Since only equal binning in both the X and Y direction makes sense, the choice is between binnings of $1\times1$, $2\times2$and $4\times4$ original 0.5'' (DPU) pixels. Default binning is $2\times2$ pixels.

Time slice duration

For each fast mode window the time slice duration must be specified, i.e., the length of individual readouts within an exposure. The allowed range is 50-90000 ms.

More details on the required input for non-default OM science windows are provided in the appropriate UHB chapter. The correct specification of OM science windows, which are constrained by various observation-dependent parameters, is very complicated. Still, it is the user's responsibility to provide correct entries. Useers proposing observations with non-default OM science windows should ask for SOC enhancement support. However, note that the available SOC support to help users will be limited. This is the reason why OM default configurations have been developed and their use is strongly recommended!

Note: Although in principle OM grism observations can be performed using an imaging mode default configuration, there is in practise no ADEQUATE default (because most of the time the central part of the FOV would not be read out, as described in § 3.3). Therefore, users who want to perform such observations, must choose the SCI USER DEF mode and fill in window settings manually on the OM exposure settings page. Detailed instructions follow in § 5.3.3.7, immediately below.