Absolute Proper motions Out side the Plane(APOP)

A step towards the GSC2.4

Zhaoxiang Qi, Yong Yu, Richard L. Smart, Mario G. Lattanzi, Zhenghong Tang, Beatrice Bucciarelli, Alberto Vecchiato,

Alessandro Spagna, Brian J. McLean

29 August, 2012

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Outline

Backgrounds

Overview on the principle and the reduction procedure

Verifications of the results

Conclusion and future works

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BackgroundsAPMs of adequate objects without P.d.E., M.d.E. and C.d.E are very important(indispensable) for Milky Way studies(e.g. rotation curves, structure...).

Most of the faint (R~20mag) catalogues are not really in the ICRS and did not deal with P.d.E., M.d.E. and C.d.E, especially their proper motions system. (e.g. USNOB1.0, PPMXL?, GSC2.3 did not publish PMs...)

Some of the faint APMs catalogues are now in the ICRS(e.g. SDSS-USNOB1, SDSS-GSC2.3...), but the sky cover is not well-distributed (limited in SDSS regions) and M.d.E. and C.d.E are still there.

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Backgrounds

APOP is a faint (R~20.8) positionally well-characterized(|b|>27deg.) and pure APMs catalogue in the ICRS. (pure=reducing the P.d.E., M.d.E., C.d.E. and using only GSC plates data)

Reduction of APOP was finished at the end of 2011.

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BackgroundsSky distribution of Schmidt plates used in APOP4239 plates-->22,525 sq.deg.

Equatorial coordinate systemGalactic coordinate system

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BackgroundsAverage accuracy of the measured coordinates on GSC plates: star 0.2-0.3 arcsec, nonstar 0.2-0.5 arcsec, A few plates data errors increased by 1.7.

Average accuracy of the photometry: 0.13-0.22 mag.

Number of observations for one object: 6-15.

Number of galaxies on one plate: 8000-20,000.

Epoch span: 25-45 years.

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Backgrounds

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Principle

Objects (stars and galaxies) with close positions, magnitudes and colors on the plate have similar systematic errors.

APMs of extragalactic-objects are always zero and not dependent on their positions, magnitudes and colors on plate.

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Principle

Do the M.d.E. and/or C.d.E. exist in plates data?

Are the M.d.E. and/or C.d.E. of stars the same as galaxies?

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Stars

Non-stars

Plate Epoch Zenith RA Dec l bXE003 1954.9 51.2 44.9 84.5 126.1 22.4XP003 1996.8 52.1 38.6 85.2 125.3 22.6

Principle

Stars

Non-stars

Distributions of stars and nonstars as a function of mag. and color

Bin=0.3mag10,000 objects/binAmplitudeX~110masY~220masNonlinear

Blue - Infrared

Principle

XJ003 - XI003(epoch span=1996.717-1996.719)

M.d.E. of all the objects

all objectsBin=0.2magAmplitude X~110masY~220masNonlinear

Blue - Infrared

PrincipleC.d.E. of all the objects

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Principle

Do the M.d.E. and/or C.d.E. exist in plates data?

Are the M.d.E. and/or C.d.E. of stars the same as nonstar?

YES and very common.

PrincipleC.d.E. of stars and nonstars

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Principle

Do the M.d.E. and/or C.d.E. exist in plates data?

Are the M.d.E. and/or C.d.E. of stars the with nonstar?

Yes and very common.

Yes, very similar.

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Reduction procedure

P.d.E. of stars after using

MovingSub-Plate method

pseudo-proper motions of real galaxies as a function of position. ( after picking out from nonstars)

P.d.E. of stars as a function of plate position after the cubic polynomials fitting.

XP715 epoch=1996.3XE494 epoch=1955.3(l=266.9, b=69.2)

M.d.E. of galaxies本C.d.E. of galaxies本

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VerificationsInternal verification: formal errors of the calibrated unknowns

Bin=0.3mag1000,000 objects/bin

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VerificationsInternal verification: APMs differences of common stars in overlap regions

Typical overlap region:1.5*6.5 sqr.deg.

Grid=0.25*0.25 sqr.deg.300 objects/grid

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Verifications External verification: Dispersion of “APMs”

of the QSOs(should be around zero) is an independent and direct determination of the qualities of stellar APMs.

108,521 QSOs found in the APOP (via cross-matching with the LQRF catalogue)

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APMs of QSOs as a function of magnitude

No significant M.d.E.

APOP

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APMs of QSOs as a function of color

No significant C.d.E.

APOP

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APMs of QSOs as a function of RA, Dec.

No significant P.d.E.

APOP

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Verifications External verification: APMs comparisons between the APOP, PPMXL and PMGS.

PPMXL: USNOB1.0+2MASS+PPMX+UCAC3 PMGS: GSC2+SDSS APOP: GSCII-database

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APOP-PPMXL

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APMs differences of stars from APOP-PPMXL

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APMs differences of QSOs from PPMXL-APOP

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APMs of QSOs inPPMXLand APOP

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