Exposure Time Calculator (ETC)
Because the vignetting of the HET primary depends on the declination of the object, telescope azimuth, and starting time of the observation, a unique ETC for HET is needed to plan observations.
- User must specify RA/Dec of object
- Tool can supply or calculate optimal telescope azimuth and start time for a given position.
- Tool can predict times and S/N ratios or limiting times and ratios for maximum time available on object.
- Works in units of real time on object and time if there were no vignetting (the two time units that can be used when writing plans).
Tool is used at all stages of planning, scheduling, and observing