CRIRES Exposure Time Calculator

Legacy version (July 04, 2016)
Provided for reference only!

Infrared Adaptive Optics Spectroscopy Mode Version 5.0.1
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Target Input Flux Distribution

Uniform (constant with wavelength) Target Magnitude and Mag.System:   
= Vega
Spectral Type (Pickles Model): (only U-K bands)
MARCS Stellar Model
Blackbody : Temperature : K
Single Line :
Lambda: The emission line is centered on the (doppler-shifted, if applied) requested wavelength specified below.
Flux: 10-16 ergs/s/cm2 (per arcsec2 for extended sources)
FWHM: nm

Spatial Distribution: Point Source Extended Source

Target Doppler Shift

No Doppler Shift
Target coordinates (J2000) and radial velocity
Coordinates (J2000) alpha:  hr min sec
delta:   deg min sec
Radial velocity
(relative to the barycenter of the Solar System)
km/s (Note: The velocity is negative for an approaching target)
Date of observation:       This information is used with the target coordinates to compute the doppler shift due to the orbital and rotational movement of the Earth (barycentric correction).
Time of observation UT:

Sky Conditions

PWV: mm Probability % of realising the PWV ≤ 2.50 mm
Seeing/Image Quality:
For point sources and non-AO instrument modes, the S/N reference area is defined by the Image Quality. For AO-modes, a model of the AO-corrected PSF is used instead. See the helpfile for details.
Seeing: arcsec FWHM in V-band at zenith (use this value in the proposal)
              Probability ---% of realising the seeing ≤ 0.80 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

Slit width: arcsec 
Reference Wavelength:
Standard Setting: (the full plot range and λreqref are automatically assigned)
Free Setting: λref= nm (and λreqref)
Requested Wavelength
λreq: nm.
The numeric results will refer to this wavelength (doppler-shifted, if applied).
In single-line mode, the emission line will be centered on this wavelength (doppler-shifted, if applied).
Wavelength range to plot:
λmin: nm
λmax: nm
The values in these fields are automatically updated to the full range when a Standard Setting changes. For a Free Setting, the λmin and λmax values are set to the corresponding full range by pressing the "set plot range" button.
The Reference Wavelength λref refers to the center (pixel 512) of detector3. Note: Wavelengths are in vacuum.
Detector mode: The detector RON depends on this mode and the DIT chosen below.

Adaptive Optics Mode:

noAO AO not enabled

Natural Guide Star

Target / Reference Source
Separation: arcsec. [0-30]
Reference Source
R mag: [0.0-16.3] B-R color (and equiv.spectral type)


S/N ratio: S/N = DIT = s
DIT range for detector modes:
[1.0s - 900s] FowlerNsamp, DIT ≥ 2s is recommended
[0.1s - 900s] FowlerNsampGrStWin
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 Radiance Spectrum in physical units (ph/s/m2/micron/arcsec2)
Total Background Spectrum
Sky Transmission Spectrum
S/N as a function of wavelength
System Efficiency and Wavelength Range
Input spectrum in physical units
Target PSF and Slitwidth (point source only)
Enslitted Energy for the Target (point source only)
N2O Gas Cell Transmission Spectrum


Legacy version (July 04, 2016)
Provided for reference only!