LOW, MEDIUM, HIGH, EXTENDED ...
how do I get "the" EPIC PSF from calview?
The calibration file GUI task
calview supports the visualization
of the four basic representations of the X-ray
Point Spread Function (PSF) that are encoded in the
Calibration Access Layer (CAL) as part of the SAS. They can be selected by
setting the
Accuracy Level parameter
in the
calview window before
invoking
View/PSF or
View/Encircled Energy/Encircled Energy (PSF):
- LOW, corresponding to a single Gaussian parameterization.
It is both energy and off-axis angle dependent, but the same for each EPIC
telescope
- MEDIUM, corresponding to 2-D maps generated from
SciSim simulations. It is
energy and off-axis angle dependent, but the same for each EPIC telescope
- EXTENDED, corresponding to a King-profile model,
energy, off-axis and telescope dependent [details can be found in
the
EPIC Calibration Status Document. Further information can
be found in the following Technical Notes:
CAL-TN-0022-1.0, EPIC-MCT-TN-011 (MOS), and EPIC-MCT-TN-012 (pn)]
- HIGH, corresponding to a three-Gaussian model,
dependent on the off-axis angle only (over a limited validity range)
As a baseline, the
EXTENDED mode gives the best
results for 1-D PSFs. A summary of its applicability
is given in
the
EPIC Calibration Status Document.
There is no good general model for a 2-D PSF yet,
due principally to the lack of the necessary in-orbit measurements.
The
MEDIUM model,
although based on simulations, and although it assumes
that all the mirror modules have the same response, may at
least give an idea of the off-axis PSF deformation.
For more detailed information on the LOW, MEDIUM and HIGH mode PSFs,
as well as the calibration files and the calibration SAS interface,
the user is referred to the
Calibration Access and Data Handbook.
