Plot 1 scores: 1|
data source:	vimos_astrometry (QC1 database)
dataset: (numbers below apply to this dataset)	delta_xsky_xccd_512_1830	▲
median:	0.884	pix
fixed thresholds:	-3...3	pix
N_data plotted:	3
[click plot for closeup]

Plot 3 scores: 1|
data source:	vimos_astrometry (QC1 database)
dataset: (numbers below apply to this dataset)	delta_xsky_xccd_1536_1830	▲
median:	-5.59	pix
fixed thresholds:	-9...-3	pix
N_data plotted:	3
[click plot for closeup]

Plot 5 scores: 1|
data source:	vimos_astrometry (QC1 database)
dataset: (numbers below apply to this dataset)	ref_xsky_xccd_1024_1220	▲
median:	-2.69	pix
fixed thresholds:	-20...20	pix
N_data plotted:	3
[click plot for closeup]

Plot 7 scores: 1|
data source:	vimos_astrometry (QC1 database)
dataset: (numbers below apply to this dataset)	delta_xsky_xccd_512_610	▲
median:	4.67	pix
fixed thresholds:	2...8	pix
N_data plotted:	3
[click plot for closeup]

Plot 9 scores: 1|
data source:	vimos_astrometry (QC1 database)
dataset: (numbers below apply to this dataset)	delta_xsky_xccd_1536_610	▲
median:	-3.64	pix
fixed thresholds:	-6...0	pix
N_data plotted:	3
[click plot for closeup]

Trending plots for monitoring VIMOS astrometry.

The CCD-to-sky transformation converts pixel coordinates onto a virtual plane which is free of instrument distortion. Coordinates of the virtual plane can be transformed into celestial coordinates using the WCS. For QC purposes, the inverse transformation is monitored by converting nine virtual data points (Xsky, Ysky) = (512, 610), (1024, 610), (1536, 610), (512, 1220), (1024, 1220), (1536, 1220), (512, 1830), (1024, 1830), (1536, 1830) into CCD coordinates (Xccd, Yccd). Plot number 5 monitors the difference between both, i.e. DeltaX0 = Xccd-Xsky or DeltaY0 = Yccd-Ysky, respectively, for the central data point. For the other eight plots, the Delta X0 (or Delta Y0) values have been subtracted: they show Xccd-Xsky-DeltaX0 or Yccd-Ysky-DeltaY0. Therefore, the central plot shows the overall shift of the transformation wherease the others show changes in the distortion.

Three astrometric fields are currently used: Region E, Region M, and Region N.

Pipeline recipe: vmskyccd.