The Exposure Time Calculators (ETCs) are online tools that predict the count rates and S/N in various observing modes given specified source characteristics. STIS provides ETCs for three separate scenarios:
Spectroscopic Science Exposures
Use this ETC to calculate the count rates and S/N ratio for a simulated spectrum of ONE source in a STIS spectroscopic observation.
Imaging Science Exposures
Use this ETC to calculate the count rates and S/N ratio for imaging observations of external targets.
Imaging Target Acquisition
Use this ETC to calculate exposure times for target acquisition exposure.
Use this ETC to recall previous calculations, using the ETC ID number. Note all STIS ETC ID numbers must include the preceding "STIS" to recall a previous calculation.
Known Issues and FeaturesKnown Issues and Features for Previous Builds
ETC 20.1 Known Issues for All Instruments