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Hubble Space Telescope
GHRS Instrument Science Report 030

GHRS Instrument Science Report 030

Preliminary Analysis of GHRS Resolving Power
Loss due to OTA Spherical Aberration  06/90

Ronald L. Gilliland

Abstract excerpted from the report:

With the recent discovery that HST will not deliver image qualities
near specifications, we must define the resulting impact on
spectroscopic resolution and throughput. In the GHRS with apertures of
0.25" and 2.0" (SSA and LSA respectively) square, the impact is
primarily: 1) in the SSA a throughput loss to 25% of originally
expected sensitivity, or a loss of 1.5 magnitudes, and 2) a point
source observed in the LSA will retain about 80% of expected
throughput, but suffer a resolution degradation of about a factor of
two.