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VISIR Exposure Time Calculator

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Infrared Imaging Mode Version 3.2.1
Description.
F.A.Q
Performance

Input Flux Distribution

Uniform (constant with wavelength)
Blackbody: Temperature: K
Greybody: Temperature: K, Exponent:
Object Flux scaled to: mJy , at the central wavelength of the selected configuration.
 
Single line: Wavelength: nm
  Flux: 10-16 W/m2
  FWHM: nm (the minimal width is set by the sampling).

Magnitudes and line flux are given per arcsec2 for extended sources.

Spatial Distribution: Point Source Extended Source

Sky Conditions

Airmass :
Seeing : arcsec

Instrument Setup

Filter: Selecting the filter sets the observation band
[ #'filter position in wheel', 'lower cutoff /nm'- 'upper cutoff /nm' ] 'filter name'
Objective: mas/pixel

Results

S/N ratio: S/N = Total integration time (without overheads) INT=NDIT*DIT. In reality, the optimal DIT depends on the atmospheric conditions at the time of observation - the actual partition of NDIT is done on-the-fly. In this model, a DIT typical for the chosen filter is assigned, and NDIT is computed according to the S/N or INT requested by the user.
Exposure Time: INT = s

In imaging, the calculations correspond to the sensitivity obtained with chopping and nodding in perpendicular direction, such that all 4 beams appear on the detector.

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

S/N as a function of Exposure Time
Input spectrum in physical units
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