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I. Extended Source Calibration: Main Page
Introduction:
Extended sources need to be calibrated differently than point
sources because the flux fills the slit. In principle, an extended
source with a known surface brightness distribution and spectrum
should be sufficient to derive the calibration. However such a source
does not exist -- sources like the Moon are too bright for the IRS.
The zodiacal background is another extended source which can be used
but it is weak and its spectrum and strength are not well known.
Moreover, they vary from region to region. Thus an absolute
calibration for extended sources is not possible. The best we can do
is to derive an approximate calibration to give users an idea of the
extent of the correction that may be required. -- our approach is
described in these pages.
NEXT: 'Page 2: Approach'
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