XMM-Newton Science Analysis System
atthkgen (atthkgen-1.20.1) [xmmsas_20070308_1802-6.6.0]
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- The OM Tracking History Files give only relative displacements as
attitude information, and how this will be translated into absolute RA and Dec
is still uncertain. Perhaps in the future it could be done via the task
in conjunction with OAL_getAttitude though this is still
unknown, and may imply that a large fraction of the OM pipeline may need to be
run early in the PPS.
- It is thought, at the moment, that the AHF may only have a very few
number of entries in it, and as such, atthkgen
may seem not
well suited to such a situation. Note though that it is envisaged that the
movement offset threshold at which new AHF entries will be input may be
reduced from 2.5 arcsec to 0.5 arcsec. This will
give many more AHF entries.
- If GTIs are to be produced from this file, then it may be important
that the output be an additional PPS product. If however, the file is
easily and quickly recreatable by the user (e.g. so long as the OM chain does
not have to be re-run, for instance), then it may not need to be a product.
- This file is needed as input for the attcalc
task, where the
mean/median attitude values are taken as the PNT attributes.
XMM-Newton SOC/SSC -- 2007-03-08