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Hubble Space Telescope
NICMOS Expsoure Time Calculators (ETCs)

The Exposure Time Calculators (ETCs) are online tools that predict the count rates and S/N in various observing modes given specified source characteristics.

Use the following interface for imaging observations.


Use the following interface for all grism observations.

NICMOS Spectroscopic ETC

Known Issues

To access your previous ETC requests, visit the Previous Requests Page.

For coronagraphic observers, please refer to this advisory note.

For problems or questions, please email

The old ETC is still available. It has more limited functionality and it has not been updated. Known problems and limitations are described here. It will be retired soon.

Old Nicmos Imaging ETC