
Date: Mon, 6 Nov 2000 13:53:28 +0100 (MET)
From: Niels Joergen Westergaard <njw@dsri.dk>
Subject: JEMX Interactive Background Handling
To: allan@dsri.dk, oxborrow@dsri.dk, sb@dsri.dk
MIME-Version: 1.0
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Hej,

her er mig forslag til, hvad vi fandt ud af i formiddags:





What should the goals be for the Interactive Background Handling?

The following note is an attempt to clarify the required capabilities
of the Interactive Background Handling software.

In the ISDC standard analysis the background subtraction is performed
in an automatic way based on a data base (set up by Sami et al.)
with a set of standard background
spectra and a set of standard spatial (detector) distributions. Based
the S/C positions in its orbit, the INTEGRAL monitor counter and the JEMX HK
values (total countrate) a background will be predicted by the ISSW and
subtracted from the shadowgrams, lightcurves and spectra.

The Interactive Background Handling will play no role for the SA.

For the offline analysis, however, we think that the Interactive
Background Handling can become a very useful tool for the user analyzing
JEMX data in greater depth to
  - display a detector image (or shadowgram) and/or its deviation from the
    predicted shape i.e. with some background model selection
  - show a background spectrum within user specified time limits and/or
    its deviation from the predicted shaped
  - show a background lightcurve within user specified energy limits
    and/or its deviation from the predicted shaped (IRM and HK)
    
The presence of strong sources in the FOV will make such presentations less
straightforward. It can be assumed that the properties of such strong sources
will be well known i.e. produced in the SA so that the detector data can
be corrected for these e.g. by simulations or by Stefan's photon tagging (?).

To let the user recognize an unusual situation the Interactive Background
Handling should be capable of showing the various spectra and bkg shadowgrams
in the data base.

In the event that a previously unknown background situation has been detected
by a user then it should be possible to update the data base with the new
spectrum(-a)/shadowgram(s). And then redo the analysis with user selected
background models.

It might also turn out than an unexpected background is not produced by
ionizing particles but is a celstial feature i.e. a galactic diffuse
background. The dithering pattern will help in identifying such a case,
but to include it in the analysis will probably imply a simulation. Here
we should investigate the use of skymaps (as done by IBIS ? - or see how
important this is for the SAX WFC analysis).

A User Manual will also be required for the Interactive Background
Handling.

CAO, AH, SB, and NJW

----------
Niels J. Westergaard
Danish Space Research Institute
Juliane Maries Vej 30, DK 2100 Copenhagen O
Phone: +45 35 32 57 05; FAX:  +45 35 36 24 75

