E-ELT Spectroscopic Exposure Time Calculator

This ETC is for E-ELT Spectroscopy. A detailed description is available in the E-ELT Spectroscopy ETC document.
For imaging, use the E-ELT Imaging ETC.

E-ELT Spectroscopic Mode Version 6.2.2
 
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Target Input Flux Distribution

Blackbody: T= K
Spectral Type: (only U-K bands)
MARCS Stellar Model
Powerlaw Index:           F(λ) ∝ λindex
Upload Spectrum


Target Brightness :
Vega mag = The input spectrum will be scaled to have this magnitude in the selected system.
AB mag
Flux mJy The input spectrum will be scaled to this flux at the observing wavelength (λref) chosen below.

The magnitude or flux is given per square arcsec for extended sources.

Spatial Distribution:
Point Source
Extended Source


Telescope Setup

Observatory Site:
Telescope Diameter:

Sky Conditions

Override almanac sky parameters and use instead typical fixed sky model parameters except Moon phase and airmass
Moon FLI: Airmass:
Time
Time step forward/back



Target
Target coordinates Name or ID:  
α      δ     
UT rise
culm.
set
Hour Angle azimuth altitude zenith distance airmass FLI moon/sun
phase angle
moon/target
separation
Target
Moon
Sun
An advanced almanac is available in the ESO SkyCalc sky model calculator
PWV:     mm         Probability % of realising the PWV ≤ 10.00 mm
Seeing/Image Quality:
Seeing: arcsec FWHM in V-band at zenith (use this value in the proposal)
              Probability ---% of realising the seeing ≤ 1.00 arcsec
IQ: arcsec FWHM at the airmass and wavelength of observation (to be used for the OB constraint set)
              The corresponding seeing and probability will be indicated in the ETC output page
Image Quality is not a parameter in AO modes


Instrument Setup

AO Mode:  
Observing wavelength: band (λref):
λref: nm
The numeric results will refer to λref and the wavelength range of the graphs will be centered there.
Radius of circular S/N ref. area:
.i.e. over which the S/N is calculated.
mas (on the sky) DLC=1.22 λ/D is the radius of the diffraction limited PSF core for a D=42m telescope.
Number of spectra on the detector:
i.e. number of spatial elements (spaxel) in the S/N ref. area
Spectral resolution R=λ/Δλ: IMPORTANT: please consult the documentation when using R>100,000

Results

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

The total exposure time is the product of DIT (Detector Integration Time) by NDIT (number of DITs). Instrument and telescope overheads are not taken into account.


Plots: Toggle All / No Plots

Resultant spectrum including sky
Object Spectrum only
Sky Emission Spectrum
Sky Transmission Spectrum
S/N as a function of wavelength
System Efficiency and Wavelength Range
Input spectrum in physical units
 
Debug text output
Show execution time details
Enable airmass dependent sky with separate emiss. and transmiss. files