GIRAFFE Exposure Time Calculator

Optical Multi-Object Spectroscopy Mode Version 6.2.0
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NOTE: As announced here, the fibre spatial profiles were improved in February 2015, and are now narrower and peak at higher ADU levels (10-30% higher). This will be helpful for programmes with faint targets. The ETC will issue a warning if your observations reach close to saturation. In this case, please consider shorter exposure times and/or multiple exposures. Typically this should happen only if your targets are brighter than V≈11.

Source Model

Input Flux Distribution:
Uniform (constant with wavelength) Target Magnitude and System:
=  Vega
Magnitudes are given per arcsec2
for extended sources.
Template Spectrum:
Redshift z =
Blackbody: Temperature : K
Source Geometry: Point Source  
Extended Source

Sky Conditions

Moon phase: days from new Moon
Seeing/Image Quality:
For point sources, the resulting Image Quality FWHM is approximated by a gaussian in the ETC considering the transfer functions of the atmosphere and telescope. 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

Fiber Mode (Sky Sampling):

MEDUSA mode only: Object-fiber displacement: arcsec (range: [ 0.00 ; 0.60 ]).
In other modes, this value is irrelevant and has no effect.

High resolution: Setup (λc):
Low resolution: Setup (λc):
Detector: Carreras CCD mode:



Exposure Time: s

Plots: Toggle All / No Plots

Object Spectrum
Sky Spectrum
Observed Object+Sky Spectrum
Input spectrum in physical units
Total Efficiency and Wavelength Range