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FOCAS Spectrograph Sensitivity Calculator

IFU Mode is Included

Choose 'IFU' in 5. Slit width for IFU observation.
This ETC does not need the exposure time modification in case of IFU observation.

Please note that this calculation is for dark moon phase and the SNR can be much lower when the moon is in the sky.

1. Source:
2. Grism:
3. Seeing: [arcsec]
4. Source Flux Density : [erg/s/cm^2/Γ…] (or [erg/s/cm^2/Γ…/arcsec^2] for extended source)
Caution: Flux density is not a flux!! Same flux emission line with a narrower width gives you a higher signal-to-noise ratio than the broader one.
5. Slit Width:
6. Extraction Aperture: [pixel]
7. CCD Binning:
Binning is fixed to 2x1 for IFU mode.
8. Exposure Time: [sec]