Definitions & Examples
First principle model Ray trace spectrograph model
- prescription based entirely on physical laws
- very high predictive power
- required to isolate effects while building physical models
Physical model UVES/STIS model (ray + dist.)
- prescription primarily based on physical / engineering insight
- empirical “fudge” only as unavoidable (tolerable) substitute
- sufficient predictive power for predictive calibration, forward analysis
Empirical model ETC, polyn. dispersion fits
- no physical insight required / inserted , can not be inverted
- no predictive power outside data range / when params change