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Table 2

Calibration parameters for UVB and VIS arm of X-shooter.

Order Spectral Min. Slit loss Max. Avg. Fitting No. of rms
order wavelength model wavelength wavelength dispersion function/ bandpasses [10-2] Remarks
[Å] [Å] [Å] [Å/px] polynomial
order

UVB

1 24 2989 3125 3134 0.097 Spline3/4 8 0.44 atmospheric absorption, low S/N
2 23 3115 3260 3273 0.103 Spline3/4 10 0.50 atmospheric absorption
3 22 3253 3400 3425 0.109 Spline3/4 10 0.03 atmospheric absorption
4 21 3403 3550 3592 0.115 Chebyshev/8 9 0.02
5 20 3568 3680 3777 0.122 Chebyshev/8 21 0.17
6 19 3750 3920 3981 0.129 Spline3/4 9 0.07 Hϵ,Hζ,Hη
7 18 3951 4150 4208 0.137 Chebyshev/6 17 0.10 Hδ
8 17 4175 4370 4463 0.146 Chebyshev/8 28 0.18 Hγ
9 16 4427 4666 4751 0.155 Chebyshev/10 51 0.21
10 15 4721 4970 5079 0.166 Chebyshev/12 44 0.14 Hβ
11 14 5058 5300 5456 0.178 Chebyshev/15 80 0.19
12_1 13 5446 5560 5693 0.196 Spline3/15 49 0.20 bluewards of dichroic dip
12_2 13 5693 5770 5893 0.184 Spline3/15 40 0.25 redwards of dichroic dip

VIS

1 30 5337 5480 5543 0.103 Spline3/8 36 1.85 dichroic variability, low S/N
2 29 5516 5640 5737 0.106 Spline3/8 40 0.15 dichroic variability
3 28 5709 5840 5945 0.111 Spline3/8 46 0.20 dichroic variability
4 27 5915 6050 6169 0.115 Spline3/8 46 0.15
5 26 6136 6250 6411 0.120 Spline3/9 40 0.16
6 25 6375 6525 6672 0.126 Spline3/6 32 0.12 Hα
7 24 6633 6800 6955 0.132 Chebyshev/9 48 0.22 atmospheric absorption window
8 23 6913 7100 7263 0.138 Chebyshev/9 53 0.30 atmospheric absorption window
9 22 7218 7420 7600 0.145 Spline3/6 53 0.18 atmospheric absorption window
10 21 7550 7770 7970 0.152 Spline3/8 60 0.28 atmospheric absorption window
11 20 7915 8150 8378 0.160 Spline3/6 50 0.27 atmospheric absorption window
12 19 8317 8600 8830 0.169 Spline3/6 61 0.26
13 18 8762 9050 9329 0.179 Chebyshev/6 47 0.51 atmospheric absorption window
14 17 9258 9550 9810 0.193 Chebyshev/6 24 0.92 atmospheric absorption
15 16 9790 9980 10200 0.215 Spline3/10 53 1.22 low S/N

Notes. The indices of the spectral orders as used in this paper are given in Col. 1, whereas the corresponding true spectral numbers of the dispersive element are given in Col. 2. Column 3 shows the minimum wavelength of each order, Col. 4 the wavelength at which the slit losses are estimated (close to the blaze wavelengths) and Col. 5 shows the maximum wavelength per order. The average dispersion is given in Col. 6, although the dispersion is a function of both slit and wavelength coordinate in each order. Column 7 lists the fitting functions and polynomial orders used in the sensitivity function computation. The number of underlying integration bandpasses is presented in Col. 8. The resulting rms are shown in Col. 9; however, we note that values <0.1 and bandpass numbers 10 are to be handled with care, as the fit is typically only weakly constrained in these cases. Finally, Col. 10 gives an overview of order-dependent features that might compromise the flux calibration accuracy.

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