Time Estimator Observing Condition Constraints
Nonunity atmospheric transmission effects the sensitivity of an observation both by reducing the signal from the astronomical source and by contributing additional noise photons. Water is the atmospheric constitutent which most degrades measurements in the infrared and the constituent which decreases the greatest as SOFIA climbs into the stratosphere. The time estimator includes the following as input parameters:
The atmospheric transmission for the relevant wavelength region is obtained from a lookup table produced by running the program ATRAN (Lord, 1992, NASA Technical Memorandum 103957).See (more info) for how the atmospheric transmission is included in the time estimates.