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Дата изменения: Mon Jul 9 04:02:13 2007
Дата индексирования: Sat Dec 22 11:01:21 2007
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XMM-Newton Science Analysis System


evproject (attcalc2-1.3.1) [xmmsas_20070708_1801-7.1.0]

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Calculating the PNT keywords

The RA_PNT, DEC_PNT and PA_PNT keywords, together with the AVRG_PNT keyword which records the type of average used, are meant to describe the average value of the spacecraft attitude during the exposure. The way in which they are calculated however is controlled by the source chosen for the attitude information, as follows:

• attsource=`binned': whatever values of the PNT keywords calculated by attbin and stored in the inbinnedattset dataset are simply copied over.

• attsource=`odf': PNT values are sought from the header of the dataset pointed to by pntkwdset. This should normally be the output file of atthkgen, which is the SSC product file with the name string ATTTSR. The sought keywords have the form `tsa', where `t' is either `M' for median or `A' for mean, `s' is either `AHF' or `OM', and `a' is either `RA', `DEC' or `PA'. The exact values of `t' and `s' looked for depend on the parameters withmedianpnt and odfattsource.

• attsource=`fixed': the values attra, attdec and attapos are also used for the PNT output. In this case AVRG_PNT is set to `FIXED'.