AstroWise Workshop

1
Astrometry in AW

• Overview of
• Astrometric processing

2
Astrometry in AW

• Contents
• Ingest
• Diagnostics
• Single frame astrometry
• Diagnostics, Quality Control
• Global astrometry
• Diagnostics, Quality Control
• Super global astrometry
• Potential

3
Astrometry in AW
Ingest
Single
RawScienceFrame
BiasFrame
FringeFrame
SaturatedPixelMap
MasterFlatFrame
SatelliteMap
CosmicMap
IlluminationCorrection
HotPixelMap
WeightFrame
ColdPixelMap
Global
ReducedScienceFrame
GainLinearity
AstrometricParameters
PhotometricParameters
RegriddedFrame
CoaddedRegriddedFrame
4
Ingest Astrometry

• Why
• Pointing problems
• Large pointing offsets
• Often small offsets
• Unpredictable
• 0.5 1 image size
• Principally no limit

5
Ingest Astrometry

• What
• WFI data
• How
• Frame based x-y grid
• Map all CCD x-y positions on one x-y grid
• A-priori knowledge of CCD chips on frame
• No rotation lt few degrees
• Good knowledge of pixel scale (few percent)
• opipe.astro.instrument.HeaderTranslatorWFI
• Astrometric properties of the instrument.
• CRPIX values for the chips in CRPIX1, CRPIX2
  format
• crpix_map 'ccd50' 4061., -223.,
  'ccd51' 1918., -222.,
• 'ccd52' -226.,
  -223., 'ccd53' -2366., -222.,
• 'ccd54' -2364.,
  3904., 'ccd55' -215., 3899.,
• 'ccd56' 1919.,
  3901., 'ccd57' 4061., 3898.

6
Ingest Astrometry

• Large offset determination
• (dx, dy) domain
• with large errorbars 100 pixels
• Application of offset
• Refinement using triangulation method
• Offset
• Rotation
• Scale

7
Ingest Astrometry

• Where
• Example
• www.astro-wise.org/portal
• -gt dbview
• -gt index of tables
• -gtAstrometricCorrection
• -gt select all

8
Ingest Astrometry

• CD matrix
• CD1_1 xx
• CD1_2 xy
• CD2_1 yx
• CD2_2 yy
• Update
• Astrom object
• Product
• RawScienceFrame

9
Single frame astrometry

• Standard pipeline reduction
• Reduction per CCD
• Overscan/Flat/Bias
• Astrometry

10
Single frame astrometry

• Pipeline processing single CCDs
• Input
• RawScienceFrame
• Preastrom
• Pointing offset correction per CCD
• Small rotation/scaling correction
• Allow tight association extracted/reference
  objects
• Astrom
• Single CCD astrometric solution

11
Single frame astrometry
ASTROM_KWLIST ('VERBOSE', 'DEBUG'),
('NITER', 5), ('XMIN',
0.0), ('XMAX', 32767.0),
('YMIN', 0.0), ('YMAX',
32767.0), ('PDEG', 2),
('FDEG', 1, 0, 0),
('XPIXSIZE', 1.000000),
('YPIXSIZE', 1.000000), ('
DEFAULT USED RA', None), ('
DEFAULT USED DEC', None), ('
DEFAULT USED ERR', None), ('
DEFAULT USED XPOS', None), ('
DEFAULT USED YPOS', None), ('
DEFAULT USED FIELD', None), ('
DEFAULT USED CAMERA', None),
(' DEFAULT USED ERRPOS', None),
(' DEFAULT USED XM2', None),
(' DEFAULT USED YM2', None),
(' DEFAULT USED CORR', None),
(' DEFAULT USED CRVAL1', None),
(' DEFAULT USED CRVAL2', None),
(' DEFAULT USED CRPIX1', None),
(' DEFAULT USED CRPIX2', None),
(' DEFAULT USED CDELT1', None),
(' DEFAULT USED CDELT2', None),
(' DEFAULT USED XWID', None),
(' DEFAULT USED YWID', None),
(' DEFAULT USED EPOCH', None),
(' DEFAULT USED DATA_TYPE', None)

• Preastrom
• Pointing offset correction
• Small rotation/scaling correction
• Allow tight association
• extracted/reference objects
• Astrom
• PDEG3
• opipe.astro.external.LDAC
• opipe.astro.main.Astrom
• conf LDAC.astromconf.get_kw_dict()
• confPDEG' 3
• LDAC.astrom(incats, outcats, 'dither.pairs',
  'dither.residuals', conf)

12
Single frame astrometry

• Diagnostisc
• Log
• Throught the iteration sequence the Rms and max
  values should decrease to smaller values to end
  up Rmslt 2.5 and maxlt 10.0. If these values are
  not reached, definitely something is wrong.

172619 - LDAC End of equation solution
0.000000 s iteration 0 172619 - LDAC Rms
and max ref stars residuals for camera 0
13.206169 and 57.039865 172619 - LDAC End
of equation solution 0.000000 s iteration 1
172619 - LDAC Rms and max ref stars residuals
for camera 0 9.251933 and 38.200649 172619
- LDAC End of equation construction 0.001999 s
iteration 2 172619 - LDAC Rms and max ref
stars residuals for camera 0 6.055043 and
27.733644 172619 - LDAC End of equation
construction 0.002000 s iteration 3 172619 -
LDAC Rms and max ref stars residuals for camera
0 2.916056 and 17.896422 172619 - LDAC End
of equation construction 0.001999 s iteration 4
172619 - LDAC Rms and max ref stars residuals
for camera 0 1.695296 and 8.931968
13
Single frame astrometry

• Diagnostisc
• Log
• First column contains X related solution, second
  column Y related solution. So here the WCS is a
  rotated one
• Third column gives solution errors

172619 - LDAC Distortion coefficients for
camera 0 172619 - LDAC (arcseconds)
(radians) 172619 - LDAC
-0.0007247 0.35 /- 0.000173 -3.689e-06
0.001781 /- 8.82e-07 X1Cheb0(F) 172619 -
LDAC -0.3461 -0.0001404 /- 4.24e-05
-0.001762 -7.149e-07 /- 2.16e-07 1YCheb0(F)
172619 - LDAC -0.0004552 0.001882 /-
6.17e-05 -2.317e-06 9.581e-06 /- 3.14e-07
X21Cheb0(F) 172619 - LDAC -4.725e-05
0.0002249 /- 2.84e-05 -2.405e-07 1.145e-06 /-
1.44e-07 XYCheb0(F) 172619 - LDAC
-0.0007643 0.0004423 /- 1.56e-05 -3.891e-06
2.252e-06 /- 7.92e-08 1Y2Cheb0(F)
X -0.0007247 x 0.35 y
-0.0004552 x2 -4.725e-05 xy -0.0007643
y2 and Y -0.3461 x -0.0001404
y 0.001882 x2 0.0002249 xy
0.0004423 y2
14
Single frame astrometry

• Diagnostisc
• Correlation matrix
• The number of reference stars large for a good
  solution. 6 Free parameters, -gt 12 pairs for
  statistical accuracy. In general lt 50 is not so
  good.
• The correlation matrix highest values on diagonal
  and all 0 on the other positions. X related and Y
  related parameters are correlated, but there
  should not be any cross dependencies between X
  and Y.
• Matrix is ordered (X, Y, X2, XY, Y2).
  Offset with the columns direction X related
  solutions and rows direction Y related solutions.

172619 - LDAC Number of reference stars
386 172619 - LDAC Number of overlap stars
0 172619 - LDAC Min and Max of covariance
matrix 172619 - LDAC (radians)2
(")2 172619 - LDAC -0.000000 0.000000
-0.000096 0.033090 172619 - LDAC 1000
0 992 0 0 991 172619 - LDAC
0 1000 0 913 0 0 172619 -
LDAC 992 0 1000 0 0 969
172619 - LDAC 0 913 0 0 0
0 172619 - LDAC 0 0 0 0
0 0 172619 - LDAC 991 0 969
0 0 1000
15
Single frame astrometry

• Diagnostics
• Residuals catalog
• Original astrom call
• Extract to ascii catalog
• The ascii catalog contains the residuals in
  Ra,Dec, the Ra and Dec of the extracted object
  and the X,Y coordinates of the reference and
  extracted objects (Note only true in case of
  pipeline astrom, not so for Global Astrom)

astrom -i tmp1118762778.2.cat1 -o
tmp1118762778.2.cat7 -p tmp1118762778.2.cat6 -c
astrom.conf -r ldac.ast.cat.residuals
ldactoasc -i ldac.ast.cat.residuals -t RESIDUALS
-k DRa DDec Ra Dec Xpos1 Ypos1 Xpos2 Ypos2 gt
res.asc
16
Single frame astrometry

• Diagnostics
• -Plots

17
Single frame astrometry
18
Single frame astrometry

• Quality Control
• Positional accuracy
• Reference catalog (USNO)
• 0.3 arcsec on large scales
• 0.15 arcsec on small scales (relative)
• Extracted object lt-gt Reference stars
• RMS extracted objects 0.1 arcsec at 5 s
• RMS residuals at 5 s lt 0.5 arcsec
• Max residuals lt 1.5 arcsec
• Solution accuracy
• Errors on astrometric parameters
• All stderr from solution
• Number of reference stars

MEAN_DRA MEAN_DDEC SIG_DRA SIG_DDEC NREF x_err y_
err xx_err xy_err yy_err field_err
19
Single frame astrometry
20
Single frame astrometry

• Product
• RegriddedFrame
• AstrometricParameters
• Full astrometric solution

21
Global astrometry

• What
• Set of overlapping pointings
• -d date (in yyyy-mm-dd format)
• -c chip name
• -f filter name
• -i instrument name
• -o object name (full name or regular
  expression)
• -g AssociationListName
• Equal camera/CCDs
• Irrelavant filters, number of pointings
• GAstrom
• GAstrometric
• Set of sourcelists lists
• One associate list

22
Global astrometry
23
Global astrometry

• Input
• ReducedScienceFrame
• Product
• RegriddedFrame
• Astrometric Parameters
• Full astrometric solution

24
Global scaling parameter 4200 Distortion
coefficients for camera 0 (arcseconds)
(radians) -0.2404 0.003929
/- 7.55e09 -0.002448 4e-05 /- 7.69e07
X1Cheb0(F) 0.001794 0.236 /- 6.65e09
1.826e-05 0.002403 /- 6.77e07
1YCheb0(F) -0.0007422 0.0009733 /- 1.16e10
-7.557e-06 9.91e-06 /- 1.18e08
X21Cheb0(F) 0.0005092 -0.0005431 /-
9.65e09 5.185e-06 -5.529e-06 /- 9.83e07
XYCheb0(F) -0.0001865 0.0003967 /- 1.05e10
-1.899e-06 4.039e-06 /- 1.07e08
1Y2Cheb0(F) Distortion coefficients for
camera 1 (arcseconds)
(radians) 0.003618 -0.003991 /- 4.85e09
3.683e-05 -4.063e-05 /- 4.94e07
11Cheb0(F) -6.696e-05 6.302e-05 /- 4.18e09
-6.817e-07 6.416e-07 /- 4.26e07 11Cheb1(F)
-0.2349 2.26e-05 /- 2.36e09 -0.002391
2.301e-07 /- 2.4e07 X1Cheb0(F) 0.0005175
0.2376 /- 5.88e09 5.269e-06 0.002419 /-
5.98e07 1YCheb0(F) 0.001524 0.0001078 /-
1.62e09 1.551e-05 1.097e-06 /- 1.65e07
X21Cheb0(F) -0.0007697 -0.0001038 /-
2.7e09 -7.836e-06 -1.057e-06 /- 2.75e07
XYCheb0(F) -0.0004294 7.504e-05 /- 9.44e09
-4.372e-06 7.64e-07 /- 9.61e07
1Y2Cheb0(F) Distortion coefficients for
camera 2 (arcseconds)
(radians) 0.002797 -0.004364 /- 4.8e09
2.847e-05 -4.443e-05 /- 4.89e07
11Cheb0(F) -2.639e-05 2.842e-05 /- 4.16e09
-2.687e-07 2.894e-07 /- 4.24e07 11Cheb1(F)
-0.2375 1.304e-05 /- 3.28e09 -0.002418
1.328e-07 /- 3.34e07 X1Cheb0(F) 0.0007458
0.2382 /- 6e09 7.593e-06 0.002425 /-
6.11e07 1YCheb0(F) -0.001114 -0.001529 /-
2.87e09 -1.134e-05 -1.557e-05 /- 2.92e07
X21Cheb0(F) 0.0007405 0.001372 /-
3.86e09 7.54e-06 1.397e-05 /- 3.93e07
XYCheb0(F) -0.0004668 -0.0004421 /- 9.86e09
-4.753e-06 -4.501e-06 /- 1e08
1Y2Cheb0(F) Distortion coefficients for
camera 3 (arcseconds)
(radians) -0.001454 -0.0007506 /- 5.72e09
-1.48e-05 -7.642e-06 /- 5.82e07 11Cheb0(F)
1.491e-05 9.983e-06 /- 4.97e09 1.518e-07
1.016e-07 /- 5.06e07 11Cheb1(F) -0.233
-0.003578 /- 9.5e09 -0.002372 -3.642e-05 /-
9.67e07 X1Cheb0(F) 0.001226 0.237 /-
6.27e09 1.248e-05 0.002413 /- 6.38e07
1YCheb0(F) -0.001313 0.0007651 /- 1.65e10
-1.337e-05 7.789e-06 /- 1.68e08
X21Cheb0(F) -0.0005989 0.001047 /-
1.02e10 -6.097e-06 1.066e-05 /- 1.04e08
XYCheb0(F) -0.0001621 -0.0003144 /- 9.05e09
-1.65e-06 -3.201e-06 /- 9.21e07
1Y2Cheb0(F) Distortion coefficients for
camera 4 (arcseconds)
(radians) 0.01132 -0.003225 /- 5.33e09
0.0001153 -3.284e-05 /- 5.42e07 11Cheb0(F)
7.777e-05 8.901e-05 /- 4.76e09 7.918e-07
9.062e-07 /- 4.85e07 11Cheb1(F) -0.247
-5.187e-05 /- 9.14e09 -0.002515 -5.281e-07 /-
9.3e07 X1Cheb0(F) 0.001994 0.2382 /-
5.03e09 2.03e-05 0.002425 /- 5.12e07
1YCheb0(F) 0.002485 -0.0001676 /- 1.64e10
2.53e-05 -1.707e-06 /- 1.67e08 X21Cheb0(F)
-0.00076 -0.0004328 /- 8.58e09 -7.738e-06
-4.406e-06 /- 8.74e07 XYCheb0(F) 0.0001683
-0.0001669 /- 7.05e09 1.714e-06 -1.699e-06 /-
7.18e07 1Y2Cheb0(F)
Distortion coefficients for camera 5
(arcseconds) (radians)
0.002081 -0.004482 /- 5.48e09 2.118e-05
-4.563e-05 /- 5.58e07 11Cheb0(F) -3.707e-05
3.514e-05 /- 4.81e09 -3.775e-07 3.578e-07 /-
4.9e07 11Cheb1(F) -0.2374 0.0002325 /-
3.73e09 -0.002417 2.368e-06 /- 3.79e07
X1Cheb0(F) 0.000211 0.2377 /- 4.98e09
2.148e-06 0.00242 /- 5.07e07
1YCheb0(F) -0.0002855 -0.0001358 /- 3.15e09
-2.907e-06 -1.383e-06 /- 3.2e07
X21Cheb0(F) 5.123e-05 9.773e-06 /-
3.46e09 5.216e-07 9.95e-08 /- 3.52e07
XYCheb0(F) 1.248e-06 -8.585e-06 /- 6.84e09
1.271e-08 -8.741e-08 /- 6.97e07
1Y2Cheb0(F) Distortion coefficients for
camera 6 (arcseconds)
(radians) 0.002933 -0.004273 /- 5.5e09
2.986e-05 -4.35e-05 /- 5.6e07
11Cheb0(F) -1.596e-05 9.679e-05 /- 4.8e09
-1.625e-07 9.855e-07 /- 4.88e07 11Cheb1(F)
-0.2372 3.946e-05 /- 2.51e09 -0.002415
4.017e-07 /- 2.55e07 X1Cheb0(F) -2.528e-05
0.2375 /- 5.19e09 -2.574e-07 0.002418 /-
5.28e07 1YCheb0(F) 0.000543 7.79e-05 /-
1.63e09 5.528e-06 7.931e-07 /- 1.66e07
X21Cheb0(F) -0.0001597 -5.25e-05 /-
2.21e09 -1.626e-06 -5.345e-07 /- 2.25e07
XYCheb0(F) -8.57e-05 -0.0001331 /- 7.21e09
-8.725e-07 -1.355e-06 /- 7.34e07
1Y2Cheb0(F) Distortion coefficients for
camera 7 (arcseconds)
(radians) 0.003896 -0.002021 /- 5.31e09
3.967e-05 -2.058e-05 /- 5.41e07
11Cheb0(F) -2.548e-05 6.096e-05 /- 4.61e09
-2.595e-07 6.206e-07 /- 4.69e07 11Cheb1(F)
-0.2361 0.002694 /- 7.57e09 -0.002404
2.743e-05 /- 7.7e07 X1Cheb0(F) 2.115e-05
0.2376 /- 5.49e09 2.154e-07 0.002419 /-
5.59e07 1YCheb0(F) 0.0007247 0.0007687 /-
1.15e10 7.378e-06 7.826e-06 /- 1.17e08
X21Cheb0(F) -0.000292 5.78e-06 /-
7.81e09 -2.973e-06 5.885e-08 /- 7.95e07
XYCheb0(F) 6.572e-05 -0.0001192 /- 7.85e09
6.691e-07 -1.214e-06 /- 8e07
1Y2Cheb0(F) !Corrections to plate center
coordinates (arcseconds) (radians)
and plate center coordinates (radians) 1
-1.51 4.38 0.12 -7.3e-06 2.1e-05 6e-07
0.2076207 -0.5087055 6e-07 2 -1.71 4.42
0.12 -8.3e-06 2.1e-05 6e-07 0.2077600
-0.5086316 6e-07 3 -1.66 4.46 0.12
-8e-06 2.2e-05 6e-07 0.2080368 -0.5084848
6e-07 4 -1.83 4.23 0.12 -8.9e-06
2.1e-05 6e-07 0.2081750 -0.5084107 6e-07 5
-1.90 4.29 0.12 -9.2e-06 2.1e-05 6e-07
0.2078973 -0.5085568 6e-07 Number of reference
stars 3597 Number of overlap stars 7935
25
Global astrometry
26
Global astrometry
27
Global astrometry
28
Global astrometry
29
Global astrometry
30
Global astrometry

• Product
• RegriddedFrame
• AstrometricParameters

31
Global astrometry

• Final product
• CoaddRegiddedFrame
• Selection list for Coadd must/may be equal to
  GAstrom

32
Global astrometry

• Quality Control
• Positional accuracy
• Reference catalog (USNO)
• 0.3 arcsec on large scales
• 0.15 arcsec on small scales (relative)
• Extracted object lt-gt Reference stars
• RMS extracted objects 0.1 arcsec at 5 s
• RMS residuals lt 0.5 arcsec
• Max residuals lt 1.5 arcsec
• Extracted object lt-gt Extracted objects
• RMS extracted objects 0.1 arcsec at 5 s
• RMS residuals lt 0.2 arcsec
• Max residuals lt 0.6 arcsec

MEAN_DRA MEAN_DDEC SIG_DRA SIG_DDEC
33
Global astrometry

• Quality Control
• Solution accuracy
• Reference objects
• Errors on astrometric parameters
• All stderr from solution
• Number of reference stars
• lt 0.3 arcsec /sqrt(Nref/PDEG)
• Overlap pairs
• Errors on astrometric parameters
• All stderr from solution
• Number of pairs
• Offset among dither pointings
• lt 0.1 arcsec /sqrt(Nover/PDEG)

NREF x_err y_err xx_err xy_err yy_err (xxx_err xxy
_err xyy_err yyy_err) field_err
34
Global astrometry
35
Global astrometry

• Quality Control
• Pre- and Post coadd PSF
• Dithering cases sub-sampling -gt sharper images
• PSFregridded gt PSFcoadded
• No anisotropy

36
Super global astrometry

• Potential solution sky-wise
• Database stores
• Sourcelists
• Relations, creation history
• Separate into distinct, independent effects
• Instrument
• Chips on baseplate
• Litho masks
• Camera
• Mounting, filters, ADC
• Telescope
• Pointing, remount/resurface, reconstruct

37
Super global astrometry

• Potential solution sky-wise
• Variability of effects
• Constant elements
• Chips mounted on base
• Time evolution
• Discontinuities
• (un)mounting parts of instrument/camera/telescope
• Relations with ambient
• Temperature
• Humidity

38
Super global astrometry

• Potential solution sky-wise
• Error budget
• RMS position extracted sources 0.1 pixelsize
  0.02 arcsec
• Overlap statistics sources x overlaps
• Fixed frame (whole sky) of overlapped pointings
• Connect to astrometric reference catalog
• Characteristics
• Large scale and small scale high precision
• Use more precise less dense astrometric catalogs
  Hipparcos lt0.001 arcs, Tycho lt0.03 arcsec