
X-Authentication-Warning: mizar.astro.helsinki.fi: smaisala owned process doing -bs
Date: Wed, 8 Nov 2000 19:20:58 +0200 (EET)
From: Sami Maisala <smaisala@astro.helsinki.fi>
To: Niels Joergen Westergaard <njw@dsri.dk>
cc: Allan Hornstrup <allan@dsri.dk>, Stefan Larsson <stefan@idun.astro.su.se>, juhani.huovelin@astro.helsinki.fi, eesko@astro.helsinki.fi, Peter Kretschmar <peter.kretschmar@obs.unige.ch>, Carol Anne Oxborrow <oxborrow@dsri.dk>, sb@dsri.dk
Subject: JEMX Interactive Background Handling
MIME-Version: 1.0



Dear colleagues,

I know you all have been thinking what features we should include on the
interactive Background handling. My basic idea is have a tool where user
can select indenpendently different parts of background models  and after
each selection user can 'see' that effect by shadowgram  or
spectral shape (Possibly real image). When user is satisfied with
selections models can be saved. In my point of view this gives user
possibility to make many variations of background models and make a
selection which is appropriate.   


In standard analysis j_bkg_model selection gives automatically spatial
models, spectrum catalogue index tables and scaling factors. If user is
not satisfied these selections it could be possible to launch
this interactive BKG handling.

Interactive BKG  could be useful to examine shadowgram and spectra
before background substraction and after that. We all know there is going
to be instrument background which is not coming through the coded mask and
it might have effects what are not yet predictable  and  must be
removed. The shape of instrument background is probably like a cup
which is settled edge on the detector. I have done simulations without 
instrument background and the events distribution is quite 'constant' over
detector in shadowgram. The visualization of shadowgram, background model
and substracted shadowgram  could be one way to estimate the quality of
background selection/model.
     

Main things:

   - user can choose different spatial and spectral background models
     freely or by given parameters: orbit, attitude, sun angle and 
     radiation level 
     
   - display wanted models (spectral and spatial)
    	
   - make a selections and save them
 
   - substract selected model from shadowgram/spectra  and see the result
     immediately
  
   - make a new re-estimation of scaling factors and make a recursive
     selections.

   - make a selections by given time intervall inside SWG	

   - Add new models to the database  	

Problems:

   - One of the basic limitations  is that background selection is based
     on data which is unique to particulary science window. That means the
     interactive background tool is confided in one SWG.  

   - should we add possibility to use image reconstruction? 	

Regards,

Sami 

-- 
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*	Sami Maisala					      *
*   Sami.Maisala@Astro.Helsinki.Fi   			      *
*   PL 14 Kopernikuksentie 1 00014 Helsingin yliopisto	      *
*   +358 (09)-19122907           *   Fax (09)-19122952        *
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