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SINFONI Exposure Time Calculator |
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The SINFONI ETC is an exposure time calculator for the ESO Spectrograph for INtegral Field Observations in the Near Infrared, SINFONI, which uses the SINFONI AO module. The HTML/Java based interface allows to set the simulation parameters and examine interactively the model generated graphs. The ETC programs allow easy comparison of the different options relevant to an observing program, including target information, instrument configuration, variable atmospheric conditions and observing parameters. The ETCs are maintained on the ESO web servers to always provide up-to-date information reflecting the known performance of ESO instruments.
The input page presents the entry fields and widgets for the target information, expected atmospheric conditions, instrument configuration, observation parameters such as exposure time or signal-to-noise, and output selection. An "Apply" button submits the parameters to the model executed on the ESO Web server. The results page presents the computed results, including number of counts for the object and the sky, signal-to-noise ratios, instrument efficiencies, PSF size etc.. The optional graphs are displayed as images and interactive Java applets as well as ASCII and PDF formats for further analysis and printing.
All magnitudes are in the Vega system - unless otherwise indicated.
You must select the filter and filter magnitude for proper scaling of the template spectrum. Available filters are V, J, H and K. For extended sources, the magnitude must be given per square arc second.Since ETC version 6.0.0, the sky background radiance and transmission model in the SINFONI ETC is based on the Cerro Paranal advanced sky model.
Since version 6.0.0, the definitions of seeing and image quality used in the ETC follow the ones given in Martinez, Kolb, Sarazin, Tokovinin
(2010, The Messenger 141, 5)
originally provided by Tokovinin (2002, PASP 114, 1156) but corrected by Kolb (ESO Technical Report #12):
Seeing is an inherent property of the atmospheric turbulence, which is independent of the telescope that is observing through the atmosphere; Image Quality (IQ), defined as the full width at half maximum (FWHM) of long-exposure stellar images, is a property of the images obtained in the focal plane of an instrument mounted on a telescope observing through the atmosphere. The IQ defines the S/N reference area for non-AO point sources in the ETC. With the seeing consistently defined as the atmospheric PSF FWHM outside the telescope at zenith at
500 nm, the ETC models the IQ PSF as a gaussian, considering the gauss-approximated transfer functions of the atmosphere, telescope and
instrument, with s=seeing, λ=wavelength, x=airmass and D=telescope diameter:
For fibre-fed instruments, the instrument transfer function is not applied. The diffraction limited PSF FWHM for the telescope with diameter D at observing wavelength λ is modeled as:
\(F_{\text{Kolb}} \) is the Kolb factor (ESO Technical Report #12):
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The Paranal seeing statistics is based on the so-called UT seeing measurements obtained from the UT1 Cassegrain Shack-Hartmann wavefront sensor used for active optics.
The measurements are deconvolved in order to represent the seeing outside the dome (i.e. they are corrected for the instrument+telescope resolution).
The La Silla seeing statistics is based on the DIMM FWHM measurements corrected for the instrumental resolution.
These data come from http://www.eso.org/gen-fac/pubs/astclim/paranal/seeing/singcumul.html
Send comments and questions to usd-help@eso.org |