Bug #1198

Incorrect results for fitting of diffuse models

Added by Martin Pierrick almost 10 years ago. Updated over 9 years ago.

Status:ClosedStart date:05/13/2014
Priority:HighDue date:07/01/2014
Assigned To:Martin Pierrick% Done:

100%

Category:-
Target version:00-09-00
Duration: 50

Description

The fitted spectral parameters for a diffuse model are incorrect. This was noted by Pierrick in simulations of the LMC and also reported by Akira in studies of Orion molecular clouds. When using a simple power law for the diffuse component, both the prefactor and the spectral index are significantly off the true values.

Note that issue #1248 was open in ctools specifically for Orion.


Recurrence

No recurrence.


Related issues

Related to ctools - Bug #1248: CTA simulation of molecular cloud does not return expecte... Closed 07/08/2014
Related to GammaLib - Bug #1151: Level of fitted background Closed 02/24/2014

History

#1 Updated by Knödlseder Jürgen almost 10 years ago

  • Status changed from New to In Progress
  • % Done changed from 0 to 10

This is maybe fixed by the #1151 bug fix, but needs to be checked.

#2 Updated by Martin Pierrick over 9 years ago

  • Description updated (diff)

#3 Updated by Martin Pierrick over 9 years ago

Knödlseder Jürgen wrote:

This is maybe fixed by the #1151 bug fix, but needs to be checked.

I confirm that the problem as initially encountered was very likely due to the background fitting, which went wrong when using the IRF background (because of its rough binning) and/or when using a tabulated spectrum and too few bins in a binned likelihood analysis.

Further tests are under way to confirm that now everything is fine. More below...

#4 Updated by Knödlseder Jürgen over 9 years ago

  • Target version set to 3rd coding sprint

Hope we can fix this during the 3rd coding sprint, or at least in the days after ...

#5 Updated by Knödlseder Jürgen over 9 years ago

Is this an open issue anymore or can we close that?

#6 Updated by Knödlseder Jürgen over 9 years ago

  • Target version changed from 3rd coding sprint to 00-09-00

#7 Updated by Martin Pierrick over 9 years ago

On my side things are now OK, at least for the cases I have worked on. Note however that I never tried the new IRF background with rebining, so cannot guarantee that this is safe (I kept working with tabulated spectra and gaussian profiles).

#8 Updated by Knödlseder Jürgen over 9 years ago

  • Status changed from In Progress to Closed
  • % Done changed from 10 to 100

Close that now.

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