X-SHOOTER Exposure Time Calculator

Redshift
z =

Target Magnitude and Mag.System:

=		Vega
		AB

Magnitudes are given per arcsec² for extended sources

MARCS Stellar Model

Upload Spectrum

Blackbody

Temperature: K

Power Law

Index: F(λ) ∝ λ^index

Emission Line

Lambda:	nm
Flux:	10-16 ergs/s/cm2 (per arcsec2 for extended sources)
FWHM:	nm

Spatial Distribution:

Point Source

Extended Source

	Moon FLI:	Airmass:
	Almanac

Almanac

Time
	UT	Time step forward/back
	MJD

Target
	Target coordinates Name or ID:
	α ^° δ ^°

	UT rise culm. set	Hour Angle	azimuth	altitude	zenith distance	airmass	FLI	moon/sun phase angle	moon/target separation
Target
Moon
Sun

An advanced almanac is available in the ESO SkyCalc sky model calculator

PWV: mm Probability % of realising the PWV ≤ 10.00 mm

Seeing/Image Quality:


	Turbulence Category: (FWHM of the atmospheric PSF outside the telescope at zenith at 500 nm)

	IQ: arcsec FWHM at λ= nm (of long-exposure of stellar images at airmass of observations)
Image Quality is not a parameter in AO modes
		The corresponding seeing and turbulence category will be indicated in the output page
Image Quality is not a parameter in AO modes

The output will always include the IQ at λ=600nm and the IQ at the central λ of each arm

Arm selection, Exposure Times and Detector modes:

Arm	Slit Width	Exp.Time	NDIT	NEXP or NINT	Detector Mode (gain) (spatial×spectral binning) (readmode)
UVB:		Texp: s		NEXP:
VIS:		Texp:s		NEXP:
NIR:		DIT:s	NDIT:	NINT:

Note! The current version of the ETC includes the 0.6" and 0.9" NIR slits without the K band blocking filter. For the preliminary performances of the new 0.6" and 0.9" slits with the K band blocking filter please refer to the X-shooter User Manual.

In UVB and VIS, the total exposure time T is the product of Texp (Exposure Time) and NEXP (Number of EXPosures): T = Texp × NEXP.

In NIR, the total exposure time T is the product of DIT (Detector Integration Time), NDIT (Number of DITs) and NINT (Number of INTegrations): T = DIT × NDIT × NINT.

Note! Stray-light contribution in the NIR arm is not accounted for. This effect is increased for wide slits (increased background) and faint, K>14 targets (higher percentage of total flux due to stray light), and could result in a factor 3-5 higher noise than predicted.

Include exposure times for S/N: (currently not enabled for NIR)

X-SHOOTER Exposure Time Calculator

Target Input Flux Distribution

Sky Conditions

Instrument Setup

Results