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   PR # 21515
    We propose to observe four close pointings (10 ks each) within the   
    northern part of the Cygnus Loop supernova remnant.  This part is    
    optically weak, comprising mostly "pure X-ray" gas. The east         
    (pointings A and D) shows a smooth spatial structure and a relatively
    hard spectrum, whereas the west (pointings B and C) is strongly      
    structured and much softer. The good spectral resolution of ASCA/SIS,
    and its spectro-imaging capabilities, will allow to go beyond one or 
    two temperatures fitting, and to investigate questions pertaining to 
    abundance variations (due to grain sputtering) or ionization delays. 
    We already have obtained ROSAT observations of this field, which will
     help constraining the spectrum at its low energy end.               
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