The atthkgen
output file is accessed by attcalc
for
the mean and median pointing values over the observation (nothing else, when
attitudelabel=ahf, attcalc
calls the OAL anew). If this
file (default name: atthk.dat) doesn't exist in the current directory,
a warning message is given, and no PNT attributes are propagated. A boolean
parameter withatthkgen exists to determine whether the task should use
any atthkgen output file.
It is still unclear at present how the OM tracking history file will
look, and how the attitude information will be accessed from this file
(perhaps through a combination of omatt
and OAL_getAttitude).
The parameter imagesize (default 0.36 degrees [= 21.6 arcminutes])
is needed to define the range of the X and Y coordinates and
all the WCS attributes. For normal pointings the default value should be
used. Larger numbers can be used for instance when
constructing a dataset over several pointings over a large field.
The `position angle' used is in actuality an `astronomical
position angle' (see XMM-MOC-TN-0109-OAD and INT-SYS-FD-TN-0004-OAD). This
angle is counted from the celestial north in the mathematically positive
sense around the axis pointing from the object towards the observer (i.e.
anticlockwise from the observer's point of view, looking towards the sky).
This is now in line with SciSim.
