Michelle Integration Time Calculator

In the four sections of this form, select the appropriate astronomical source, instrument, telescope, observing condition and observation parameters. Click on the calculate button () at the bottom of any section to submit the parameters from all the sections to the server or the reset button () to reset all parameters to their defaults. The results are reported in a separate web page that can be resized and printed.

General guidance on use of the Integration Time Calculators (ITCs) is available; specific help on each section of the form is available by following the more info and other (blue highlighted) links. Note: at this time Netscape 6 and 6.01 do not work with web forms. Changes, enhancements and bugs within the ITC are listed chronologically.

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 mag AB mag Jy W/m^2/um ergs/s/cm^2/A ergs/s/cm^2/Hz (e.g. 19.3 mag or 2e-17 W/m^2/um)
	Extended source having ...(When this option is selected the image quality selection in section 3 of the ITC is disabled.)
		Gaussian profile with full width half maximum of arcsec and spatially integrated brightness of mag AB mag Jy W/m^2/um ergs/s/cm^2/A ergs/s/cm^2/Hz (e.g. 19.3 mag or 2e-17 W/m^2/um)
		Uniform surface brightness mag / sq arcsec AB mag / sq arcsec Jy / sq arcsec W/m^2/um / sq arcsec ergs/s/cm^2/A / sq arcsec ergs/s/cm^2/Hz / sq arcsec (e.g. 21.6 mag / sq arcsec)
		Exponential profile with spatially integrated brightness mag AB mag Jy W/m^2/um ergs/s/cm^2/A ergs/s/cm^2/Hz (e.g. 19.3 mag or 2e-17 W/m^2/um) and half-light radius of arcsec (disabled)
		Elliptical r^(1/4) profile with spatially integrated brightness mag AB mag Jy W/m^2/um ergs/s/cm^2/A ergs/s/cm^2/Hz (e.g. 19.3 mag or 2e-17 W/m^2/um) and half-light radius of arcsec (disabled)
	User-defined 2D image read from file (disabled)
with the above brightness normalisation applied in filter U (0.36um) B (0.44um) V (0.55um) R (0.67um) I (0.87um) J (1.25um) H (1.65um) K (2.2um) L' (3.76um) M' (4.77um) N (10.5um) Q (20.1um) band or at a wavelength micron (latter option disabled)
Spectral distribution: (more info) Choose one SED, the redshift and extinction
	Library spectrum of a non-stellar object Planetary nebula (NGC7027) starburst galaxy (M82) Pre-main sequence star (HD100546) Galactic center AFGL230 (M10II star with Silicate absorption) AFGL3068 (Late N-type star, optically thick carbon based dust) Alpha Boo (K1.5III star) Alpha Car (F0II star) Beta And (M0IIIa star) Beta Gru (M5III star) Gamma Cas (B0IVe star) Gamma Dra (K5III star) l1551irs (young stellar object) NGC 1068 (Dusty active galaxy) NGC2023 (Reflection Nebula) NGC2440 (line dominated PN) O Cet (M7IIIa Star with silicate emission) Orion Bar (Dusty HII region) rscl (N-type Dusty Carbon Star, SiC emission) txpsc (N-type Visible Carbon Star) WR 104 (Wolf-Rayet Star + dust) WR 34 (Wolf-Rayet Star)
	Library spectrum of a star with spectral type O5V O8III B0V B5-7V B5III B5I A0V A0III A0I A5V A5III F0V F0III F0I F5V F5V-w F6V-r F5III F5I G0V G0V-w G0V-r G0III G0I G2V G5V G5V-w G5V-r G5III G5III-w G5III-r G5I K0V K0V-r K0III K0III-w K0III-r K0-1II K4V K4III K4III-w K4III-r K4I M0V M0III M3V M3III M6V M6III M9III
	Single emission line at wavelength micron with line flux W/m^2 ergs/s/cm^2 and line width km/s on a flat (in wavelength) continuum of flux density W/m^2/um ergs/s/cm^2/A
	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
...and subject to dust reddening by a foreground screen (see more info on the extinction law) having a visual extinction of Av = mag (disabled)

Instrument (Michelle) and telescope configuration

Instrument optical properties:
Filter:	N' (10.1um - 12.5um) Qa (18.1um) Si-1 (7.9um) Si-2 (8.7um) Si-3 (9.7um) Si-4 (10.4um) Si-5 (11.7um) Si-6 (12.3um) No Filter(LowN LowQ Spectroscopy)	Focal plane unit:	none 0.19 arcsec slit 0.38 arcsec slit 0.57 arcsec slit 0.76 arcsec slit 1.52 arcsec slit
Grating:	none (imaging) LowN MedN1 MedN2 LowQ EchelleN EchelleQ	Spectrum central wavelength:	um
Polarimetry:	disabled  enabled
Detector properties:
Read noise and dark current have not yet been measured for the new Michelle science array but should not be significant for background-limited observations. Following are the values assumed by the ITC:
Read noise of 4,000 e- per pixel
Dark current of 270,000 e-/s per pixel
Telescope configuration:(more info)
Mirror coating: aluminium  silver
Instrument port: up-looking (2 reflections)  side-looking (3 reflections)
Wavefront sensor for tip-tilt compensation: PWFS   (no OIWFS)

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:	best 20%-ile	70%-ile	85%-ile	any
Sky transparency (cloud cover):	best 20%-ile	50%-ile	70%-ile	90%-ile	any
Sky transparency (water vapour):	best 20%-ile	50%-ile	80%-ile	any
Sky background: Any (see explanatory notes)
Typical air mass during observation:	<1.2	1.5	2.0

Details of observation

Calculation method:(more info) Select imaging or spectroscopy and the calculation method (note: second method is not available for spectroscopy)
Imaging or  spectroscopy ...
		Total S/N ratio resulting from a total time of secs and with a fraction of exposures that observe the source (number of individual exposures will be calculated from assumed frame time)
		Total integration time to achieve a S/N ratio of and with a fraction of exposures that observe the source
Analysis method: (more info)
Software aperture that gives 'optimum' S/N ratio and with a sky aperture times the target aperture
Software aperture of diameter (or slit length) arcsec and with a sky aperture times the target aperture
Output:
For spectroscopy, autoscale or specify limits for plotted spectra (lower wavelength um and upper wavelength um)

Last update May 24, 2007; Brian Walls