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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