Source detection tasks by gegeshandong

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									Source detection tasks




    SASWG meeting
    Potsdam 15/11/06
            edetect_chain
• For SAS 7.0 updated to support new
  features of detection tasks
• => Provides 2XMM style detection pipeline
  for users
                     emldetect
• Problem in RC2 version: cases where error routine
  fails to converge wrong (positional) errors.
• Various reasons:
   – Parameter variables single precision.
   – Initial error estimates.
   – Insufficient margins of fft working images.


• Fixed in v 4.44.21
    emldetect – parameter errors

• Problem in RC2 version: cases where error routine
  fails to converge wrong (positional) errors.
• Various reasons:
   – Parameter variables single precision.
   – Initial error estimates.
   – Insufficient margins of fft working images.


• Fixed in v 4.44.21
   Emldetect – parameter errors
• Problem in RC2 version: cases where error routine
  fails to converge wrong (positional) errors.
• Various reasons:
   – Parameter variables single precision.
   – Initial error estimates.
   – Insufficient margins of fft working images.


• Fixed in v 4.44.21
                                   300 fields, 25000 sources
                  eposcorr
• Calibration of threshold on fit likelihood in
  relation to „spurious“ likehood
                  eposcorr

                     Like=2 like_null+9




2XMMp threshold: like > 2*like_null + 5
                  eposcorr




2XMMp threshold: like > 2*like_null + 5
                  eposcorr

                     Like=2 like_null+9




2XMMp threshold: like > 2*like_null + 5
                  eposcorr

                     Like=2 like_null+9




2XMMp threshold: like > 2*like_null + 5
       Sensitivity calibration

• Simulations of typical EPIC observations
  – 5.0ks, 10ksec, 20ksec, 40ksec
  – low and increased background
  – 100 simulations each
• Comparing detection rates in simulated
  observations with esensmap maps.
• Simulating logNlogS
• ....
Sensitivity maps
Sensitivity maps
extended source detection
            Main problems
• Point source confusion => emldetect
• Inaccurate PSF
• Detector background features

								
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