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 with spectral type
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)
Detector bias (i.e. well depth) set for low or high flux mode (typically <2.5µm and >2.5µm respectively)
Read noise set for low noise, medium noise, or high noise mode (typically narrow band faint object 1-2.5µm imaging/spectroscopy, JHK imaging and bright object 1-2.5µm spectroscopy, and 3-5µm imaging and spectroscopy, respectively)
Dark current of 0.25 e-/s
Telescope configuration:(more info)
Mirror coating: aluminium silver
Instrument port: side-looking (3 reflections)
Wavefront sensor for tip-tilt compensation: PWFS Altair
Altair properties:(more info)
AO guide star
arcsec AO guide star brightness
Field Lens: OUT IN(Required for LGS) Altair Mode: NGS LGS


Observing condition constraints

Note: you should 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
Sky transparency (cloud cover): 50%/Clear 70%/Cirrus 80%/Cloudy Any
Sky transparency (water vapour): 20%/Low 50%/Median 80%/High Any
Sky background: 20%/Darkest 50%/Dark 80%/Grey Any/Bright
Typical air mass during observation: <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 an 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 with a fraction of exposures that observe the source
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)