JavaScript is not present or has been disabled, please turn on JavaScript if you have it and reload this page! The ETC will function correctly but the throughput will not change with wavelength and has been set to its best value.


Signal-to-noise calculator

S/N ratio to be specified for a reference wavelength of microns

Observation parameters

total exposure time s

Object parameters

Point source with
= mag
W m-2Å-1 at reference wavelength

Extended source with
= mag arcsec-2
W m-2Å-1arcsec-2 at reference wavelength

Telescope and Instrument

Telescope diameter m
Lenslet diameter arcsec
No pixels per resolution element
Grating lines/mm

Background parameters


Seeing FWHM arcsec
Interline sky background photons/s/m2/micron/arcsec2