Astronomical source definition

Spatial profile and brightness: (more info)
Choose one of point, extended or user-defined source profile and the brightness in any filter/wavelength
Point source (nominal PSF) with spatially integrated brightness (e.g. 19.3 mag or 2e-17 W/m²/µm)
Extended source havings ... (When this option is selected the image quality selection in section 3 of the ITC is disabled.)
Gaussian profile with full width half maximum (including seeing) of arcsec and spatially integrated brightness of (e.g. 19.3 mag or 2e-17 W/m²/µm)
Uniform surface brightness (e.g. 21.6 mag/arcsec²)
with the above brightness normalisation applied in filter band

Spectral distribution: (more info)
Choose one SED, the redshift and extinction
Library spectrum of a non-stellar object
Library spectrum of a star (300 nm - 6 µm)
Single emission line at wavelength micron with line flux and line width km/s on a flat (in wavelength) continuum of flux density
Model black body spectrum with temperature K
Model power-law spectrum (S_lambda = lambda ^ )
User-defined spectrum read from file (size < 1MB)
with the spectrum mapped to a redshift z = or a radial velocity v = km/s


Instrument (NIRI), telescope, and Altair configuration

Instrument optical properties: (more info)
Camera: Disperser:
Filter: Focal plane mask:
Detector properties: (more info)
Read mode set for:
low noise, typically narrow band faint object 1-2.5µm imaging/spectroscopy
medium noise, JHK imaging and bright object 1-2.5µm spectroscopy
high noise, 3-5µm imaging and spectroscopy
Detector bias (i.e. well depth) set for:
low flux mode, typically for wavelengths <2.5µm
high flux mode, typically for wavelengths >2.5µm
Dark current:   0.25 e-/s
Array / Subarray size: Full frame Central 768x768 Central 512x512 Central 256x256
Telescope configuration: (more info)
Mirror coating: silver
Instrument port: up-looking (2 reflections)   side-looking (3 reflections)
Wavefront sensor for tip-tilt compensation: PWFS Altair
Altair properties: (more info)
AO guide star separation: arcsec AO guide star brightness (R-band): mag
Field Lens: OUT IN (Required for LGS) Altair Mode: NGS LGS


Observing condition constraints

Please read the explanatory notes for the meaning of the percentiles and to ensure that your selected conditions are appropriate for the observing wavelength. Further details are available on the observing condition constraints pages.
Image Quality: 20%/Best 70%/Good 85%/Poor Any arcsec
Cloud Cover: 50%/Clear 70%/Cirrus 80%/Cloudy Any mag
Water Vapor: 20%/Low 50%/Median 80%/High Any
Sky Background: 20%/Darkest 50%/Dark 80%/Grey Any/Bright
Airmass: <1.2 1.5 2.0


Details of observation

Calculation method: (more info)
Select the calculation method (note: second method is not available for spectroscopy)
Total S/N ratio resulting from exposures each having coadds with exposure time of secs and with a fraction of exposures that observe the source
Total integration time to achieve a S/N ratio of using an exposure time for each exposure of secs and coadds, and with a fraction of exposures that observe the source
Telescope offset:(more info)
Dither offset size: arcsec
Analysis method: (more info)
Photometry in software aperture that gives 'optimum' S/N ratio
Photometry in software aperture of diameter (or slit length) arcsec
For spectroscopy, autoscale or specify limits for plotted spectra (lower wavelength micron and upper wavelength micron)