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4.3 Grating Characteristics

 

The grating characteristics are:

Grating rest position.
This is the position of the grating mechanism when no power is applied to the drive coils. The grating is returned to this position at the end of each measurement with the grating in order to minimize the popwer input to the ISO cryostat.
Grating scan range
The set of positions over which the Grating may be moved is limited by the design of the mechanism (the range of the mounting pivot movement). The Grating Scan range defines this set of positions to be those for which the drive current is less than 12 mA.
Grating spectral element
This is the Full Width Half Maximum of the of the instrument spectral response, in the Grating Mode, to an unresolved spectral line. It determines the resolving power of the instrument in medium resolution observations.



N.Trams, ISO Science Operations Team
Using inputs from:
C.Gry, T. Lim, LWS Instrument Dedicated Team
A.Harwood, P.E.Clegg, B.Swinyard, K.King, LWS Instrument Team
S.Lord, S.Unger, IPAC.