8-12-2015AstroWise Workshop 14 – 18 november 2005 Astrometry in AW Overview of Astrometric...

21-04-23 AstroWise Workshop14 – 18 november 2005

Astrometry in AWAstrometry in AW

Overview of

Astrometric processing


Astrometry in AWAstrometry in AW

Contents• Ingest

– Diagnostics

• Single frame astrometry– Diagnostics, Quality Control

• Global astrometry– Diagnostics, Quality Control

• Super global astrometry– Potential


Single

Global

Ingest

Astrometry in AWAstrometry in AWRawScienceFrameBiasFrame

FringeFrame

MasterFlatFrame

IlluminationCorrection

HotPixelMap

ColdPixelMap

GainLinearity

PhotometricParameters

ReducedScienceFrame

CoaddedRegriddedFrame

SatelliteMapCosmicMap

RegriddedFrame

SaturatedPixelMap

WeightFrame

AstrometricParameters


Ingest AstrometryIngest Astrometry

• Why– Pointing problems– Large pointing offsets– Often small offsets– Unpredictable

• 0.5 – 1 image size• Principally no limit



• 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 < 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.]}



– Large offset determination

• (dx, dy) domain• with large errorbars

~100 pixels

– Application of offset– Refinement using

triangulation method • Offset• Rotation• Scale



• Where– Example

www.astro-wise.org/portal -> dbview

-> index of tables

->AstrometricCorrection

-> select all

http://www.astro-wise.org/portal



– CD matrix• CD1_1 = xx

• CD1_2 = xy

• CD2_1 = yx

• CD2_2 = yy

– Update • Astrom object

– Product• RawScienceFrame


Single frame astrometrySingle frame astrometry

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



• Pipeline processing single CCD’s– Input

• RawScienceFrame

– Preastrom• Pointing offset correction per CCD• Small rotation/scaling correction• Allow tight association extracted/reference objects

– Astrom• Single CCD astrometric solution



• Preastrom– Pointing offset correction– Small rotation/scaling correction– Allow tight association

extracted/reference objects

• Astrom– PDEG=3– opipe.astro.external.LDAC– opipe.astro.main.Astrom

conf = LDAC.astromconf.get_kw_dict()

conf[‘PDEG'] = 3

LDAC.astrom(incats, outcats, 'dither.pairs', 'dither.residuals', **conf)

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)]



• Diagnostisc– Log

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

17:26:19 - LDAC: End of equation solution 0.000000 s iteration 0 17:26:19 - LDAC: Rms and max ref stars residuals for camera 0: 13.206169 and 57.039865 17:26:19 - LDAC: End of equation solution 0.000000 s iteration 1 17:26:19 - LDAC: Rms and max ref stars residuals for camera 0: 9.251933 and 38.200649 17:26:19 - LDAC: End of equation construction 0.001999 s iteration 2 17:26:19 - LDAC: Rms and max ref stars residuals for camera 0: 6.055043 and 27.733644 17:26:19 - LDAC: End of equation construction 0.002000 s iteration 3 17:26:19 - LDAC: Rms and max ref stars residuals for camera 0: 2.916056 and 17.896422 17:26:19 - LDAC: End of equation construction 0.001999 s iteration 4 17:26:19 - LDAC: Rms and max ref stars residuals for camera 0: 1.695296 and 8.931968



• 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

X = -0.0007247 * x + 0.35 * y + -0.0004552 * x^2 + -4.725e-05 * x*y + -0.0007643 * y^2 and Y = -0.3461 * x + -0.0001404 * y + 0.001882 * x^2 + 0.0002249 * x*y + 0.0004423 * y^2

17:26:19 - LDAC: Distortion coefficients for camera 0 17:26:19 - LDAC: (arcseconds) (radians) 17:26:19 - LDAC: -0.0007247 0.35 +/- 0.000173 -3.689e-06 0.001781 +/- 8.82e-07 X*1*Cheb0(F) 17:26:19 - LDAC: -0.3461 -0.0001404 +/- 4.24e-05 -0.001762 -7.149e-07 +/- 2.16e-07 1*Y*Cheb0(F) 17:26:19 - LDAC: -0.0004552 0.001882 +/- 6.17e-05 -2.317e-06 9.581e-06 +/- 3.14e-07 X**2*1*Cheb0(F) 17:26:19 - LDAC: -4.725e-05 0.0002249 +/- 2.84e-05 -2.405e-07 1.145e-06 +/- 1.44e-07 X*Y*Cheb0(F) 17:26:19 - LDAC: -0.0007643 0.0004423 +/- 1.56e-05 -3.891e-06 2.252e-06 +/- 7.92e-08 1*Y**2*Cheb0(F)



• Diagnostisc– Correlation matrix

• The number of reference stars large for a good solution. 6 Free parameters, -> 12 pairs for statistical accuracy. In general < 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, X**2, X*Y, Y**2). Offset with the columns direction X related solutions and rows direction Y related solutions.

17:26:19 - LDAC: Number of reference stars: 386 17:26:19 - LDAC: Number of overlap stars: 0 17:26:19 - LDAC: Min and Max of covariance matrix: 17:26:19 - LDAC: (radians)**2 (")**2 17:26:19 - LDAC: -0.000000 0.000000 -0.000096 0.033090 17:26:19 - LDAC: 1000 0 992 0 0 991 17:26:19 - LDAC: 0 1000 0 913 0 0 17:26:19 - LDAC: 992 0 1000 0 0 969 17:26:19 - LDAC: 0 913 0 0 0 0 17:26:19 - LDAC: 0 0 0 0 0 0 17:26:19 - LDAC: 991 0 969 0 0 1000



• 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 > res.asc



• Diagnostics-Plots



• Quality Control– Positional accuracy

• Reference catalog (USNO)– 0.3 arcsec on large scales– 0.15 arcsec on small scales (relative)

• Extracted object <-> Reference stars – RMS extracted objects 0.1 arcsec at 5 σ – RMS residuals at 5 σ < 0.5 arcsec– Max residuals < 1.5 arcsec

– Solution accuracy• Errors on astrometric parameters• All stderr from solution• Number of reference stars

MEAN_DRAMEAN_DDECSIG_DRASIG_DDEC

NREFx_erry_errxx_errxy_erryy_errfield_err



• Product– RegriddedFrame

• AstrometricParameters– Full astrometric solution


Global astrometryGlobal 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/CCD’s– Irrelavant: filters, number of pointings

• GAstrom– GAstrometric

• Set of sourcelists lists• One associate list



• Input– ReducedScienceFrame


• Astrometric Parameters– Full astrometric solution


Global scaling parameter 4200Distortion coefficients for camera 0 (arcseconds) (radians) -0.2404 0.003929 +/- 7.55e+09 -0.002448 4e-05 +/- 7.69e+07 X*1*Cheb0(F) 0.001794 0.236 +/- 6.65e+09 1.826e-05 0.002403 +/- 6.77e+07 1*Y*Cheb0(F)-0.0007422 0.0009733 +/- 1.16e+10 -7.557e-06 9.91e-06 +/- 1.18e+08 X**2*1*Cheb0(F) 0.0005092 -0.0005431 +/- 9.65e+09 5.185e-06 -5.529e-06 +/- 9.83e+07 X*Y*Cheb0(F)-0.0001865 0.0003967 +/- 1.05e+10 -1.899e-06 4.039e-06 +/- 1.07e+08 1*Y**2*Cheb0(F)Distortion coefficients for camera 1 (arcseconds) (radians) 0.003618 -0.003991 +/- 4.85e+09 3.683e-05 -4.063e-05 +/- 4.94e+07 1*1*Cheb0(F)-6.696e-05 6.302e-05 +/- 4.18e+09 -6.817e-07 6.416e-07 +/- 4.26e+07 1*1*Cheb1(F) -0.2349 2.26e-05 +/- 2.36e+09 -0.002391 2.301e-07 +/- 2.4e+07 X*1*Cheb0(F) 0.0005175 0.2376 +/- 5.88e+09 5.269e-06 0.002419 +/- 5.98e+07 1*Y*Cheb0(F) 0.001524 0.0001078 +/- 1.62e+09 1.551e-05 1.097e-06 +/- 1.65e+07 X**2*1*Cheb0(F)-0.0007697 -0.0001038 +/- 2.7e+09 -7.836e-06 -1.057e-06 +/- 2.75e+07 X*Y*Cheb0(F)-0.0004294 7.504e-05 +/- 9.44e+09 -4.372e-06 7.64e-07 +/- 9.61e+07 1*Y**2*Cheb0(F)Distortion coefficients for camera 2 (arcseconds) (radians) 0.002797 -0.004364 +/- 4.8e+09 2.847e-05 -4.443e-05 +/- 4.89e+07 1*1*Cheb0(F)-2.639e-05 2.842e-05 +/- 4.16e+09 -2.687e-07 2.894e-07 +/- 4.24e+07 1*1*Cheb1(F) -0.2375 1.304e-05 +/- 3.28e+09 -0.002418 1.328e-07 +/- 3.34e+07 X*1*Cheb0(F) 0.0007458 0.2382 +/- 6e+09 7.593e-06 0.002425 +/- 6.11e+07 1*Y*Cheb0(F) -0.001114 -0.001529 +/- 2.87e+09 -1.134e-05 -1.557e-05 +/- 2.92e+07 X**2*1*Cheb0(F) 0.0007405 0.001372 +/- 3.86e+09 7.54e-06 1.397e-05 +/- 3.93e+07 X*Y*Cheb0(F)-0.0004668 -0.0004421 +/- 9.86e+09 -4.753e-06 -4.501e-06 +/- 1e+08 1*Y**2*Cheb0(F)Distortion coefficients for camera 3 (arcseconds) (radians) -0.001454 -0.0007506 +/- 5.72e+09 -1.48e-05 -7.642e-06 +/- 5.82e+07 1*1*Cheb0(F) 1.491e-05 9.983e-06 +/- 4.97e+09 1.518e-07 1.016e-07 +/- 5.06e+07 1*1*Cheb1(F) -0.233 -0.003578 +/- 9.5e+09 -0.002372 -3.642e-05 +/- 9.67e+07 X*1*Cheb0(F) 0.001226 0.237 +/- 6.27e+09 1.248e-05 0.002413 +/- 6.38e+07 1*Y*Cheb0(F) -0.001313 0.0007651 +/- 1.65e+10 -1.337e-05 7.789e-06 +/- 1.68e+08 X**2*1*Cheb0(F)-0.0005989 0.001047 +/- 1.02e+10 -6.097e-06 1.066e-05 +/- 1.04e+08 X*Y*Cheb0(F)-0.0001621 -0.0003144 +/- 9.05e+09 -1.65e-06 -3.201e-06 +/- 9.21e+07 1*Y**2*Cheb0(F)Distortion coefficients for camera 4 (arcseconds) (radians) 0.01132 -0.003225 +/- 5.33e+09 0.0001153 -3.284e-05 +/- 5.42e+07 1*1*Cheb0(F) 7.777e-05 8.901e-05 +/- 4.76e+09 7.918e-07 9.062e-07 +/- 4.85e+07 1*1*Cheb1(F) -0.247 -5.187e-05 +/- 9.14e+09 -0.002515 -5.281e-07 +/- 9.3e+07 X*1*Cheb0(F) 0.001994 0.2382 +/- 5.03e+09 2.03e-05 0.002425 +/- 5.12e+07 1*Y*Cheb0(F) 0.002485 -0.0001676 +/- 1.64e+10 2.53e-05 -1.707e-06 +/- 1.67e+08 X**2*1*Cheb0(F) -0.00076 -0.0004328 +/- 8.58e+09 -7.738e-06 -4.406e-06 +/- 8.74e+07 X*Y*Cheb0(F) 0.0001683 -0.0001669 +/- 7.05e+09 1.714e-06 -1.699e-06 +/- 7.18e+07 1*Y**2*Cheb0(F)

Distortion coefficients for camera 5 (arcseconds) (radians) 0.002081 -0.004482 +/- 5.48e+09 2.118e-05 -4.563e-05 +/- 5.58e+07 1*1*Cheb0(F)-3.707e-05 3.514e-05 +/- 4.81e+09 -3.775e-07 3.578e-07 +/- 4.9e+07 1*1*Cheb1(F) -0.2374 0.0002325 +/- 3.73e+09 -0.002417 2.368e-06 +/- 3.79e+07 X*1*Cheb0(F) 0.000211 0.2377 +/- 4.98e+09 2.148e-06 0.00242 +/- 5.07e+07 1*Y*Cheb0(F)-0.0002855 -0.0001358 +/- 3.15e+09 -2.907e-06 -1.383e-06 +/- 3.2e+07 X**2*1*Cheb0(F) 5.123e-05 9.773e-06 +/- 3.46e+09 5.216e-07 9.95e-08 +/- 3.52e+07 X*Y*Cheb0(F) 1.248e-06 -8.585e-06 +/- 6.84e+09 1.271e-08 -8.741e-08 +/- 6.97e+07 1*Y**2*Cheb0(F)Distortion coefficients for camera 6 (arcseconds) (radians) 0.002933 -0.004273 +/- 5.5e+09 2.986e-05 -4.35e-05 +/- 5.6e+07 1*1*Cheb0(F)-1.596e-05 9.679e-05 +/- 4.8e+09 -1.625e-07 9.855e-07 +/- 4.88e+07 1*1*Cheb1(F) -0.2372 3.946e-05 +/- 2.51e+09 -0.002415 4.017e-07 +/- 2.55e+07 X*1*Cheb0(F)-2.528e-05 0.2375 +/- 5.19e+09 -2.574e-07 0.002418 +/- 5.28e+07 1*Y*Cheb0(F) 0.000543 7.79e-05 +/- 1.63e+09 5.528e-06 7.931e-07 +/- 1.66e+07 X**2*1*Cheb0(F)-0.0001597 -5.25e-05 +/- 2.21e+09 -1.626e-06 -5.345e-07 +/- 2.25e+07 X*Y*Cheb0(F) -8.57e-05 -0.0001331 +/- 7.21e+09 -8.725e-07 -1.355e-06 +/- 7.34e+07 1*Y**2*Cheb0(F)Distortion coefficients for camera 7 (arcseconds) (radians) 0.003896 -0.002021 +/- 5.31e+09 3.967e-05 -2.058e-05 +/- 5.41e+07 1*1*Cheb0(F)-2.548e-05 6.096e-05 +/- 4.61e+09 -2.595e-07 6.206e-07 +/- 4.69e+07 1*1*Cheb1(F) -0.2361 0.002694 +/- 7.57e+09 -0.002404 2.743e-05 +/- 7.7e+07 X*1*Cheb0(F) 2.115e-05 0.2376 +/- 5.49e+09 2.154e-07 0.002419 +/- 5.59e+07 1*Y*Cheb0(F) 0.0007247 0.0007687 +/- 1.15e+10 7.378e-06 7.826e-06 +/- 1.17e+08 X**2*1*Cheb0(F) -0.000292 5.78e-06 +/- 7.81e+09 -2.973e-06 5.885e-08 +/- 7.95e+07 X*Y*Cheb0(F) 6.572e-05 -0.0001192 +/- 7.85e+09 6.691e-07 -1.214e-06 +/- 8e+07 1*Y**2*Cheb0(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-07Number of reference stars: 3597Number of overlap stars: 7935




• AstrometricParameters



• Final product– CoaddRegiddedFrame

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



• Quality Control– Positional accuracy

• Reference catalog (USNO)– 0.3 arcsec on large scales– 0.15 arcsec on small scales (relative)

• Extracted object <-> Reference stars – RMS extracted objects 0.1 arcsec at 5 σ – RMS residuals < 0.5 arcsec– Max residuals < 1.5 arcsec

• Extracted object <-> Extracted objects – RMS extracted objects 0.1 arcsec at 5 σ – RMS residuals < 0.2 arcsec– Max residuals < 0.6 arcsec

MEAN_DRAMEAN_DDECSIG_DRASIG_DDEC



• Quality Control– Solution accuracy

• Reference objects– Errors on astrometric parameters– All stderr from solution– Number of reference stars

< 0.3 arcsec /sqrt(Nref/PDEG)

• Overlap pairs– Errors on astrometric parameters– All stderr from solution– Number of pairs– Offset among dither pointings

< 0.1 arcsec /sqrt(Nover/PDEG)

NREFx_erry_errxx_errxy_erryy_err(xxx_errxxy_errxyy_erryyy_err)field_err



• Quality Control– Pre- and Post coadd PSF

• Dithering cases sub-sampling -> sharper images

• PSFregridded > PSFcoadded

• No anisotropy


Super global astrometrySuper 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



• 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



• 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 <0.001 arcs, Tycho <0.03 arcsec

8-12-2015AstroWise Workshop 14 – 18 november 2005 Astrometry in AW Overview of Astrometric...

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