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XMM-Newton Science Analysis System Page: 1
srcdisplay
July 9, 2007
Abstract
Displays an image overlayed with the positions of detected sources.
1 Instruments/Modes
Instrument Mode
MOS, PN, OM All imaging modes
2 Use
pipeline processing no
interactive analysis yes
3 Description
This task displays a given image and plots the positions of sources listed in a separate sourcelist le.
The input image is specied via the parameter imageset and the sourcelist le (generated by eg eboxde-
tect, emldetect, srcmatch or ewavelet) is specied through the boxlistset parameter.
Circles are used to depict the source positions. The radius of these circles can be set using the sourceradius
parameter. A optional ID label can also be displayed alongside the circle, corresponding to the row num-
ber of that source in the input source list. This can be enabled through the uselabel parameter. This
helps the user to refer back to source properties documented in the source list.
These circles are in fact Ds9-type regions, which can be written out to a le for future use (for example,
when running a later DS9 session) by setting withregionfile to true, and specifying the desired le
name via the regionfile parameter.
Note that the current version computes the regions in terms of equatorial coordinates, as opposed to raw
image coordinates in previous versions. This means that the task can overlay source positions taken from
a given source list onto any image, eg a PN sourcelist can be overlayed on a MOS1 image, as long as the
image contains WCS information that maps the pixel grid onto equatorial coordinates.
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3.1 Examples
To overlay the sourcelist srclist.ds generated previously by eboxdetect on an image image.ds the
following command can be used:
srcdisplay imageset=image.ds boxlistset=srclist.ds
This would overlay circles, each of radius 5 pixels, around each source detected by eboxdetect. To
overlay circles of radius 0.01 degrees, use the following:
srcdisplay imageset=image.ds boxlistset=srclist.ds sourceradius=0.01
To perform the same as above, but also write out a DS9 region le named regions.txt, detailing the
source regions corresponding to the displayed circles,the following command could be used:
srcdisplay imageset=image.ds boxlistset=srclist.ds sourceradius=0.01 withregionfile=true
regionfile=regions.txt
4 Parameters
This section documents the parameters recognized by this task (if any).
Parameter Mand Type Default Constraints
boxlistset yes data-set boxlist.ds none
Name of dataset containing source list, output from eboxdetect.
withimageset no boolean true truejfalse
If set to true a new image data set is given in parameter imagset.
imageset no data-set image.ds none
The image on which the positions of detected sources are displayed. For withimageset=false no new
image data set shall be displayed but the sources in boxlistset will be marked on the image in the
currently active Ds9 session.
sourceradius no oat 0.01 0.0001
sourceradius
2
The radius of the displayed circles for each source, in degrees.
includesources no boolean true none
If true, then the DS9 region descriptor generated for each source is such that it INCLUDES the area
bounded by the circle; otherwise it includes everything BUT this area.
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uselabel no boolean false none
If true, a number is displayed alongside the source position, corresponding to the row number of that
source in the input source list.
withregionle no boolean true none
If true, then a le of name regionfile is written out, containing a list of DS9-type regions for each
source, corresponding to the displayed circles.
regionle no le-
name
regionle.txt none
The name of the region le.
overlay no boolean false truejfalse
If set to false any previously existing source region markers on the active image will be deleted before
the new ones are displayed. overlay=true suppresses this so any existing source markers will be left
unmodied. This is useful for e.g., comparing the results of two independent source detection runs on
the same image.
srccolor no string white black jwhite jred
jgreen jblue jcyan
jmagenta jyellow
The color of the source markers - useful in conjunction with the overlay parameter to control the display
of two or more source lists on the same image.
5 Errors
This section documents warnings and errors generated by this task (if any). Note that warnings and
errors can also be generated in the SAS infrastructure libraries, in which case they would not be docu-
mented here. Refer to the index of all errors and warnings available in the HTML version of the SAS
documentation.
error(UnableToCreateFile (error)
Cannot open a le of corresponding to the parameter regionfile.
invalidWCS (warning)
the image does not contain a WCS entry describing a projection from image coordinates to
equatorial coordinates.
corrective action: continue
NoBoxSizePresent (warning)
the source list does not contain a column BOX SIZE. This has no aect on the plotting but
may aect other tools using the srcdisplay library.
corrective action: continue
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NoPosnErrorsPresent (warning)
the source list does not contain a column RADEC ERR. This has no aect on the plotting but
may aect other tools using the srcdisplay library.
corrective action: continue
6 Input Files
1. A eboxdetect source list output. This is a dataset in which the rst table must contain
the following columns:
RA, of type real-64.
DEC, of type real-64.
and optionally:
RADEC ERR, of type real-32.
BOX SIZE, of type real-32.
2. An image dataset. This must contain a block corresponding to an n x m array. It must also
contain WCS information that describes the mapping from image coordinates to equatorial
coordinates.
7 Output Files
1. A DS9-compatible region le. This is a text le containing region descriptions for each
source. This is only written out if withregionfile is true.
8 Algorithm
1. Read in source list and generate source regions for each source, using their
positions in pixels. Write these regions to a temporary file if withregionfile
is false, otherwise to a permanent file with a name corresponding to the parameter
regionfile.
2. Invoke an imgdisplay session, using the image specified in imageset, and the
region file name as arguments.
9 Comments
The ID labeling is currently based on the ROW number. A source list could have its own
identication scheme, eg a SRC NUM or SRCNUM column that contains an ID number
for each source, which may cause slight confusion. Support is planned for that in the near
future.
References
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