Документ взят из кэша поисковой машины. Адрес оригинального документа : http://xmm.vilspa.esa.es/sas/7.1.0/doc/esensmap.ps.gz Дата изменения: Mon Jul 9 02:44:53 2007 Дата индексирования: Tue Oct 2 05:24:56 2012 Кодировка: Поисковые слова: t tauri

XMM-Newton Science Analysis System Page: 1
esensmap
July 8, 2007
Abstract
Calculate EPIC sensitivity map
1 Instruments/Modes
Instrument Mode
EPIC MOS: IMAGING
EPIC PN: IMAGING
2 Use
pipeline processing yes
interactive analysis yes
3 Description
This task creates a sensitivity map giving point source detection upper limits (vignetting corrected source
count rate corresponding to the likelihood of detection as specied in the parameter le) for each image
pixel. The task may either be called for individual energy bands or combinations of energy bands and
instruments. The upper limits are calculated by assuming Poissonian count statistics in each 3  3 pixel
detection cell, using the exposure and background values read from the input images. It is assumed that
30 upper limit calculation is meant as a reference point for a more detailed assessment of the sensitivity
of the detection process to be determined through Monte Carlo simulations.
In the case of multiple input energy bands the upper limits are expressed in units of counts per seconds for
the combined band (i.e. they refer to the detection sensitivity which would be acchieved by adding up the
photons observed in the individual bands). Pixels outside of the detection mask used by the eboxdetect
detection task as well as pixels with zero exposure time are assigned a sensitivity value of -1.0. This
also holds for pixels where { due to a failure of the esplinemap backgound task { zero or negative values
occure in the input background maps.
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4 Parameters
This section documents the parameters recognized by this task (if any).
Parameter Mand Type Default Constraints
detmasksets yes lename
list
detmask.ts
Names of detection masks
expimagesets yes lename
list
expimage.ts
Names of exposure images
bkgimagesets yes lename
list
bkgimage.ts
Names of background maps
sensimageset yes lename sensimage.ts
Name of sensitivity image
mlmin no oat 10.0 [0.1 Upper limit likelihood
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.
WrongInst (error)
Unknown instrument ID
MissingParameter (error)
Missing input le name
FileMismatch (error)
Inconsistent number of input images
FileMismatch (error)
Inconsistent instruments or bands
FileMismatch (error)
Number of detector masks not equal number of instruments
MissingAttribute (warning)
corrective action: Keyword will not be copied to output le
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6 Input Files
1. PPS product (from task EEXPMAP): EPIC exposure images (one per instrument)
2. from task ESPLINEMAP: Spline background maps (one per instrument per energy band)
3. from task EMASK: Detection masks (one per instrument)
7 Output Files
1. PPS product : EPIC sensitivity image
8 Algorithm
subroutine esensmap
Loop over image pixels:
Loop over input images:
IF detection mask == 1
Accumulate background in 3 x 3 pixel detection cell
Determine exposure in detection cell
END IF
END Loop
Evaluate cumulative Poissonian distribution
Subtract background and divide by exposure
Correct for fraction of PSF outside of the detection cell
IF exposure in pixel /= 0: Write result to output sensitivity map
END Loop
end subroutine esensmap
9 Comments
10 Future developments
References
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