What are Intermediate Result (e.g. SMA) Mapping Errors?
“Your calculated value for SMA XXX lies outside of the supported performance table range, and has been mapped to the supported value YYY” This is a common example of an +intermediate result+ being out-of-bonds — no single user input is outside the bounds of the SIM/PQ performance tables, but in combination they create an out-of-bounds condition in an intermediate result. For example, imagine you wanted to measure the proper motion of a V=12 F4 V (B-V = 0.4) star to an objective accuracy of 5 uas/yr with a N=100-measurement observation plan (over the five year SIM baseline mission). At the time of this writing (March 2007), these global astrometry parameters and the global astrometry performance tables result in a target single-measurement accuracy (SMA) of 36.5 uas. The project SMA tables don’t support measurements this coarse — the maximum SMA for a V=12 star is 26.8 uas. In this circumstance we report an error — the objective SMA exceeds the coverage in the performance model table
