Project rays generated by ChaRT onto a semi-infinite detector plane.
psf_project_ray infile outfile detector [evtfile] [simx] [simy] [simz]
[defocus] [xblur] [yblur] [ablur] [lcfile] [randseed] [geompar]
[ardlibpar] [detsubsysmod] [clobber] [verbose]
`psf_project_ray' takes the output rays generated by the
Chandra Ray Tracer (ChaRT) and projects them onto a
semi-infinite detector plane. The rays are randomly
discarded based on the mirror weights and the detector QE and
QEU (if a reference event file is used). The output is a
pseudo event list in detector coordinates (detx,dety).
If a reference event list is provided, then the rays are
projected not just to (detx,dety), but all the way to sky
coordinates (x,y). In this case, the WCS and SIM information
are extracted from the header of the event list and used in the
calculations, as long as the simx/y/z parameters are set to
"INDEF".
When the tool projects the rays onto the detector plane, the
detectors do not have edges. This is important when dealing
with a source that is near chip edges. psf_project ray
creates the "ideal" PSF, not one that gets cut off at the chip
edge. The edges should then be taken into account during
modeling by including an exposure map in the convolution.
The ChaRT website has more information, including instructions
on how to use the web interface and caveats associated with
it.
psf_project_ray HRMA_theta5.949_phi197.7_en1.7_d2.fits
projected_rays.fits "acis_evt2.fits[EVENTS]"
Project the rays from the ChaRT output, using an event
file for reference. The default random seed of 0 (the
current system time) is used for the projection.
psf_project_ray HRMA_theta5.949_phi197.7_en1.7_d2.fits
projected_rays_seed25.fits "acis_evt2.fits[EVENTS]" randseed=25
The previous example is repeated with a specific
random seed; this allows the results to be reproduced
at a later time.
psf_project_ray HRMA_theta5.949_phi197.7_en1.7_d2.fits no_ref_file.fits
evtfile="" detector=ACIS-S
The projection is done by specifying a detector
instead of providing an event file. Since no file is
available for reference, only detector coordinates are
written to the output file.
Input ChaRT ray file
The input ray file from ChaRT that contains the ray
positions and direction angles. The energy column is
assumed to be constant.
Output pseudo event list
The file containing the rays which have been projected
onto the detector. The output contains detector
coordinates and, if a reference event file was
provided, sky coordinates. The SIM information is
recorded in the file header.
Detector name
Used to set the detector and define the nominal
aimpoint (SIM position). This parameter is ignored if
an event file is provided.
Reference event file with block name
If this file is provided, the DETNAM header keyword
value overrides the value of the detector parameter.
The SIM_X/Y/Z values (also from the header) are used to
set the correct SIM position. The WCS information,
along with the nominal aspect, is used to project the
rays onto the sky.
The desired block should be specified,
e.g. "acis_evt2.fits[EVENTS]"; if it is not, ARDLIB
will use the first "interesting" extension (usually
EVENTS).
If no event file is provided, the tool cannot apply QE
weighting; however, ray weights will still be applied.
Parameter=simx (real default=INDEF units=mm)
SIM_X position
Sets the SIM_X position for the ray projection. If set
to INDEF, the value of the SIM_X keyword in the
reference event file header is used. Any other value
overrides what is defined in the header.
Parameter=simy (real default=INDEF units=mm)
SIM_Y position
Sets the SIM_Y position for the ray projection. If set
to INDEF, the value of the SIM_Y keyword in the
reference event file header is used. Any other value
overrides what is defined in the header.
Parameter=simz (real default=INDEF units=mm)
SIM_Z position
Sets the SIM_Z position for the ray projection. If set
to INDEF, the value of the SIM_Z keyword in the
reference event file header is used. Any other value
overrides what is defined in the header.
Defocus position
Similar to setting SIM_Z. SIM_Z is an absolute
position with respect to the spacecraft coordinate
system; defocus is the offset from the "best
focus", which is different for each detector aimpoint.
If the simz parameter is set, defocus should be left as
0.
Parameter=xblur (real default=0 min=0 units=arcsec)
Gaussian blur applied to rays
The final sky position of the rays can be blurred
by a Gaussian with a sigma equal to this amount of
blurring in the sky-x direction.
[Only the sky positions are affected.]
Parameter=yblur (real default=0 min=0 units=arcsec)
Gaussian blur applied to rays
The final sky position of the rays can be blurred
by a Gaussian with a sigma equal to this amount of
blurring in the sky-y direction.
[Only the sky positions are affected.]
Parameter=ablur (real default=0 min=-90 max=90 units=deg)
Rotation angle of Gaussian blur.
The final sky position of the rays can be blurred
by a Gaussian with a sigma equal to this amount of
blurring. [Only the sky positions are affected.]
Lightcurve file to assign times
If supplied, a TIME column will be added to the output
file. The times will be randomly assigned using the input
lightcurve as a probability distribution. The
lightcurve file must have a TIME and COUNTS column;
the Data Model virtual file syntax can be used to rename
columns if needed (see "ahelp dm"). The GTIs in the
input event file are NOT used. They can be applied to
the rays with dmcopy after running this tool.
The resulting file will not be time-sorted. Users can
sort the file with dmsort if desired.
Random seed
Controls which rays are allowed through based
on their weight (which is stored in a column of the ray
file) and the QE and QEU of the detector. The seed
allows control of this random process so that it's
repeatable.
If "randseed=0", the current system time will be
used. If "randseed=-1" then no randomization will occur
(all input rays will be in output file). Any other
value will be used as-is for the random seed.
Pixlib Geometry parameter file
Analysis Reference Data Library (ARDLIB) parameter file
Ardlib detector sub-system modifier
Unlike some other ARDLIB enabled tools;
psf_project_ray runs on multiple chips and as such does not have a
detsubsys parameter. This parameter allows one to modify
the internal detsubsys value to allow the response
product to be modified. Things such as skipping badpixels
be overridden (see "ahelp ardlib" for more information).
The default "BPMASK=0" skips bad pixels when the PSF
is created since the badpixel information is (typically)
already included in the exposure maps.
Overwrite the output file if it exists?
Amount of screen output created by the tool.
Four new parameters have been added to psf_project_ray.
"xblur", "yblur", and "ablur" will apply an elliptical
Gaussian randomization to the final sky positions of the rays;
the chip and detector values are unchanged.
If a lightcurve is provided in the "lcfile" parameter, times
are randomly assigned to the tool output based on the input
lightcurve model.
See the individual parameter descriptions for more information.
- calibration
-
ardlib
- tools
-
acis_bkgrnd_lookup,
acis_fef_lookup,
acis_set_ardlib,
acisspec,
aconvolve,
acrosscorr,
add_grating_orders,
add_grating_spectra,
arestore,
asphist,
dither_region,
dmarfadd,
dmcoords,
dmfilth,
dmregrid,
fullgarf,
mkacisrmf,
mkarf,
mkexpmap,
mkgarf,
mkgrmf,
mkinstmap,
mkpsf,
mkrmf,
mkwarf,
psextract,
rmfimg,
specextract
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