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 XSHOOTER: Optical and spectroscopic distortion
Format check | Order definition | 2D map

 
HC PLOTS
UVB number of lines/orders found
VIS
NIR
UVB gaps between lines (fmtck/2D mapping)
VIS
NIR
QC1 database (advanced users): browse | plot
UVB residuals for format check
VIS
NIR
UVB residuals for order definition
VIS
NIR
QC1 database (advanced users): browse | plot
UVB residuals for 2D mapping
VIS
NIR
UVB stability of line positions
VIS
NIR
QC1 database (advanced users): browse | plot

The determination of the distortion correction is done with three types of calibrations: format check (aka 1-pinhole arc), order definition (aka 1-pinhole flat) and 9-pinhole arc.

In xsh_predict the lines from a catalog are searched in the format check frame. Their positions are guessed from a prediction by the physical model, which uses a default configuration. By default xsh_predict varies only the parameters affecting 1-pinhole positions (except the distortion parameters) and the allowed ranges of variations are small. Experience showed that for temperature changes above about 2K this approach does not produce good results for UVB. For this arm therefore we allow larger variations, but vary the same parameters.

xsh_orderpos uses the updated model configuration to predict the position of the 1-pinhole flat and then fits polynomial relations to the x/y position detected.

Finally with xsh_2dmap a 9-pinhole arc is used to also update the distortion coefficients from detected line position. The nine pinhole runs along the direction of the slit length and therefore allow to determine distortions along the slit. Again only small variations are allowed, which works for all 3 arms so far. All three recipes use sigma clipping to improve the stability of the results.

The xshooter pipeline can be operated in polynomial mode and in physical model mode. The latter mode is used within ESO QC. Therefore the QC parameters are in most cases RMS values of the physical model fit and maximum deviations of individual arc lines from the model fit.

Format of the XSHOOTER raw frames. The UVB-arm frame is rotated by 180 deg to match the spectroscopic orientation of the VIS-arm frame. The NIR-arm frame is rotated by 90 deg to match the spectroscopic orientation of the VIS-arm frame. The VIS-arm frame is not modified, its fromat is the reference. Letters 'X' and 'Y' in the physical model QC parameters refer the the VIS-arm

TABKE_CAP1 and mean X = spatial, or cross-dispersed direction and Y = negative dispersion direction. TABLE_END

Format check
Format check | Order definition | 2D map

QC1_parameters

FITS key QC1 database: table, name definition class* HC_plot** more docu
QC.NLINE.FOUND.CLEAN xshooter_format..nline_found_clean y-position of lower right reference line [pixel] [docuSys coming]
QC.LINE.DIFMAX xshooter_format..line_difmax maximum distance in pixel between 2 identified arc lines CAL [docuSys coming]
QC.LINE.DIFMAX.ORD xshooter_format..line_difmax_ord order in which the maximum distance occurs CAL [docuSys coming]
QC.MODEL.ANNEAL.RESX_MIN xshooter_format..fit_resx_min minimum residual of fit along x-axis ENG [docuSys coming]
QC.MODEL.ANNEAL.RESX_MAX xshooter_format..fit_resx_max maximum residual of fit along x-axis ENG [docuSys coming]
QC.MODEL.ANNEAL.RESX_RMS xshooter_format..fit_resx_rms rms of residuals of fit along x-axis ENG [docuSys coming]
QC.MODEL.ANNEAL.RESY_MIN xshooter_format..fit_resy_min minimum residual of fit along y-axis ENG [docuSys coming]
QC.MODEL.ANNEAL.RESY_MAX xshooter_format..fit_resy_max maximum residual of fit along y-axis ENG [docuSys coming]
QC.MODEL.ANNEAL.RESY_RMS xshooter_format..fit_resy_max maximum residual of fit along y-axis ENG [docuSys coming]
[calculated by QC procedure] xshooter_format..x_ul x-position of upper left reference line [pixel] CAL [docuSys coming]
[calculated by QC procedure] xshooter_format..x_ur x-position of upper right reference line [pixel] CAL [docuSys coming]
[calculated by QC procedure] xshooter_format..x_ll x-position of lower left reference line [pixel] CAL [docuSys coming]
[calculated by QC procedure] xshooter_format..x_lr x-position of lower right reference line [pixel] CAL [docuSys coming]
[calculated by QC procedure] xshooter_format..y_ul y-position of upper left reference line [pixel] CAL [docuSys coming]
[calculated by QC procedure] xshooter_format..y_ur y-position of upper right reference line [pixel] CAL [docuSys coming]
[calculated by QC procedure] xshooter_format..y_ll y-position of lower left reference line [pixel] CAL [docuSys coming]
[calculated by QC procedure] xshooter_format..y_lr y-position of lower right reference line [pixel] CAL [docuSys coming]
*Class: KPI - instrument performance; HC - instrument health; CAL - calibration quality; ENG - engineering parameter
**There might be more than one.

The temperature variations of individual arc line positions is monitored via the x|y _ u|l l|r parameters. Some arc line show up twice, in different orders.

In the UVB arm the following arc lines are used:

  • UL: 325.737, the order=23 instance is used
  • LL: 303.350
  • UR: 586.031
  • LR: 550.999, the order=13 instance is used

In the VIS arm the following arc lines are used:

  • UL: 567.383, the order=29 instance is used
  • LL: 561.206, the order=29 instance is used
  • UR: 1033.27
  • LR: 933.476, the order=17 instance is used

Trending

The number of identified arc lines in the format check (1 pinhole arc) is monitored in the upper left box of UVB together with the 1/9 number of identified arc lines in the 2dmap (9 pinhole arc) and the number of identified orders in the oderdef (1 pinhole flat). All three calibrations are acquired in all three arms, in one and the same readmode and binning.

The largest gap between two arc lines derived from the format check and the 2map as well as the number of orders derived from the order definition and the 2map is monitored UVB.

Scoring&thresholds Format check

fmt_lines is scored with thresholds set to ~+-10%
fmt_gap is not scored
the format check residuals and the and arc positions are not scored

History

Date event
2010-09-19 new pipeline finds more lines in VIS data
2010-01-26 new NIR lamp provides brighter lines
2012-02-01 isolated lines position monitoring no longer supported for all detector areas
2019-04-01 static calibration has been updated, a new arc line list. Several format check residuals have new mean values.

Algorithm Format check

The physical model is fit to the 1-pinhole arc line Echelle spectrum image.

Order definition
Format check | Order definition | 2D map

QC1_parameters

FITS key QC1 database: table, name definition class* HC_plot** more docu
QC.ORD.ORDERPOS.NDET xshooter_order..n_order_det number of detected ordersHC [docuSys coming]
QC.ORD.ORDERPOS.RESIDMIN xshooter_order..resid_min minimum residual of fit ENG [docuSys coming]
QC.ORD.ORDERPOS.RESIDMAX xshooter_order..resid_max maximum residual of fit ENG [docuSys coming]
QC.ORD.ORDERPOS.RESIDRMS xshooter_order..resid_rms rms of residuals of fit ENG [docuSys coming]
QC.ORD.ORDERPOS.RESELMIN xshooter_order..resel_min minimum residual of fit after sigma clipping ENG [docuSys coming]
QC.ORD.ORDERPOS.RESELMAX xshooter_order..resel_max maximum residual of fit after sigma clipping ENG [docuSys coming]
QC.ORD.ORDERPOS.RESELRMS xshooter_order..resel_rms rms of residuals of fit after sigma clipping ENG [docuSys coming]
*Class: KPI - instrument performance; HC - instrument health; CAL - calibration quality; ENG - engineering parameter
**There might be more than one.

Trending

The number of orders identified in the 1-pinhole flat calibrations and the residuals of the physical model fit are monitored.

Scoring&thresholds Order definition

The number of orders is scored. It must be 12 for UVB, 12 for VIS and 15 for NIR.
The order residua parameters are scored with very relaxed thresholds.

History

Date event
2010-09-19 new pipeline finds more lines in VIS data
2010-01-26 new NIR lamp provides brighter lines
2012-02-01 isolated lines position monitoring no longer supported for all detector areas

Algorithm Order definition

The XSHOOTER physical model is fit to the 1-pinhole Echelle flat field spectrum

2D map
Format check | Order definition | 2D map

QC1_parameters

FITS key QC1 database: table, name definition class* HC_plot** more docu
QC.NLINE.FOUND.CLEAN xshooter_2dmap..nline_found_clean number of clean arc lines foundHC [docuSys coming]
QC.LINE.DIFMAX xshooter_2dmap..line_difmax maximum distance in pixel between 2 identified arc lines CAL [docuSys coming]
QC.LINE.DIFMAX.ORD xshooter_2dmap..line_difmax_ord order in which the maximum distance occurs CAL [docuSys coming]
QC.MODEL.ANNEAL.RESX_MIN xshooter_2dmap..fit_resx_min minimum residual of fit along x-axis ENG [docuSys coming]
QC.MODEL.ANNEAL.RESX_MAX xshooter_2dmap..fit_resx_max maximum residual of fit along x-axis ENG [docuSys coming]
QC.MODEL.ANNEAL.RESX_RMS xshooter_2dmap..fit_resx_rms rms of residuals of fit along x-axis ENG [docuSys coming]
QC.MODEL.ANNEAL.RESY_MIN xshooter_2dmap..fit_resy_min minimum residual of fit along y-axis ENG [docuSys coming]
QC.MODEL.ANNEAL.RESY_MAX xshooter_2dmap..fit_resy_max maximum residual of fit along y-axis ENG [docuSys coming]
QC.MODEL.ANNEAL.RESY_RMS xshooter_2dmap..fit_resy_max maximum residual of fit along y-axis ENG [docuSys coming]
*Class: KPI - instrument performance; HC - instrument health; CAL - calibration quality; ENG - engineering parameter
**There might be more than one.

Trending

The number of identified arc lines in the 9 pinhole arc is monitored in the upper right box of UVB. All three calibrations are acquired in all three arms, in one and the same readmode and binning.

Scoring&thresholds 2D map

2dmap_lines is scored with thresholds set to ~+-10%
The scatter in the residual parameters is dominated be arc lines in the order overlapping region, which can be identified in either one or two orders. So far the thresholds for the residual parameters are kept tolerant.

History

Date event
2010-09-19 new pipeline finds more lines in VIS data
2010-01-26 new NIR lamp provides brighter lines
2012-02-01 isolated lines position monitoring no longer supported for all detector areas
2019-04-01 The arc line lists have been updated, physical model residuals have changed

Algorithm 2D map

The xshooter physical model is fit to the 9-pinhole calibrations. The fit quality is expressed in term of parameters describing the residuals.

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