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XMM-Newton Science Analysis System


atthkgen (atthkgen-1.20.1) [xmmsas_20080701_1801-8.0.0]

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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 omatt 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.