ELT Imaging Exposure Time Calculator

This ETC is for ELT Imaging. A detailed description is available in the ELT Imaging ETC document.
For spectroscopy, use the ELT Spectroscopic ETC.

ELT Imaging Mode Version 6.4.0
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Target Input Flux Distribution

Target Brightness:
Vega mag = Spectral Type: If a Vega or AB magnitude is given in a band which differs from the observation band, the spectral type will be used to convert to the observation band. Otherwise the spectral type is ignored.
AB mag
Flux mJy The entered flux refers to the central wavelength of the observation band chosen below. The target's spectral type is not considered in this case.

Source Geometry:
Point Source S/N Ref.Area:  pixels The light (object and sky) is collected over this area and the resulting S/N refers to this area.
Surface Brightness The target mag. is taken as surface brightness (mag/arcsec2).
The light (object and sky) is collected over 1 arcsec2.
Extended Object rh: mas rh is the observed half-light radius, as seen on the detector, taking into account seeing or AO-correction. The light (object and sky) is collected over the disc with area A= π rh2.

System Configuration

Observatory Site:
Telescope Diameter: m In the current ETC model, the diameter affects only the light collecting area, not the resolution (PSF), see the documentation for details.
Observation Band:
Pixel Scale: mas/pixel  
AO Mode: The AO-performance (Encircled Energy) is derived from a table (see the documentation) with typical values for the given AO-mode, pixel scale and wavelength band.


DIT: seconds  +  hours

S/N ratio: S/N=
Exposure Time: NDIT=

The total exposure time is the product of DIT (Detector Integration Time) by NDIT (number of DITs). This exposure time does not take into account instrument and telescope overheads.

On submission the model can generate the following graphs/additional information:
(input parameters are replicated in the output page)

S/N as a function of Exposure Time. Plotting range:%