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APEX Modules: Fit Radius
Namelist Trigger: run_fit_radius
Output Directory Keyword: OUTPUT_DIR (apex_1frame.pl); COADD_DIR (apex.pl)
Default Output Directory: <output_dir> (apex_1frame.pl); <output_dir>/Coadd (apex.pl)
Depends on: Detect
Output Directory Keyword: OUTPUT_DIR (apex_1frame.pl); COADD_DIR (apex.pl)
Default Output Directory: <output_dir> (apex_1frame.pl); <output_dir>/Coadd (apex.pl)
Depends on: Detect
PURPOSE
-
This module determines a fitting area for each source in the detect
table. If not run, the fitting will be done for each detection
using the fixed value of Fitting_Area_X,Y defined in the Source Estimate module. The term "Fit Radius" is a little misleading, since all fitting is done in a box, not a circle.
PARAMETER BLOCK
-
&FIT_RADIUS
&END
INPUTS
-
None.
OUTPUTS
-
The fitting area size Fit X,Y in pixels is written into the
detect table (*_detect.tbl).
DISCUSSION
Running of this module is optional, but it should generally be run for point sources with good signal-to-noise. Another option is to specify the fitting area size in the Source Estimate Module using namelist parameters Fitting_Area_X and Fitting_Area_Y. However in this case the same fitting area size is used for all point sources. If both namelist parameters Fitting_Area_X, Fitting_Area_Y and columns FitX, FitY in the detect table are given as input for point source fitting, the former is used.The module Fit Radius reads in a detection list with two required fields "x" and "y". It reads the image corresponding to the detection list and the uncertainty image. The input image is mean-subtracted. The module also optionally reads a coverage map. If a coverage map is given, then the uncertainty values are multiplied by sqrt(coverage). For each detection, a search is performed in the x and y directions. The program starts at the detection pixel and goes up and down in the y-direction and left and right in the x-direction. It compares the values of the mean-subtracted input image and the corresponding uncertainty values. It finds the closer distance one has to go in each direction until the mean-subtracted image pixel values drop below the uncertainty level.
Figure 1: The mean-subtracted input image (blue,thick) and the uncertainty image (red,thin) have two intersection points x1 and x2. xps is the position of the detection. In this case, the fitting size FitX = 2(x2 - xps), since (x2-xps) < (xps - x1).
All the content of the input table is copied into the output table. Two more columns FitX and FitY are added.
\char comment = Output from DETECT, version 1.00
| srcid| x| y| flux| BlendId| BlendSize| FitX| FitY|
|i |r |r |r |i |i |i |i |
0 2.50 229.50 1.328e+03 0 0 5 5
1 3.30 77.50 1.369e+03 0 0 7 5
2 3.40 190.55 1.338e+03 1 2 5 9
3 4.82 190.24 1.435e+03 1 2 7 10
| Contents | ~ | Previous: APEX Modules - Extract MedFilter | ~ | Next: APEX Modules - Select Detect |
