POSSII IMAGES ASTROMÉTRIC REDUCTION Reduction methods and their influence on Theta and Rho measures Ignacio Novalbos O.A.N.L. Barcelona

O.A.N.L. Barcelona 2010 ORIGIN AND OBJECTIVE

O.A.N.L. Barcelona 2010 Relative astrometry of new pairs discovered on POSSII plates OAG Common Proper Motion Wide Pairs Survey ORIGIN

O.A.N.L. Barcelona 2010 OBJECTIVE Knowing which astrometric reduction method / software get the most accurate, when we measured on images from the POSSII-J, which usually present saturation for stars with magnitude <12.

O.A.N.L. Barcelona 2010 METHODOLOGY

METHODOLOGY - - Selection of pairs from the Catalog of Rectilinear Elements - - Getting POSS II images of each pair - - Get the time of each plate from the FITS header - - From the linear elements and using a linear regression we calculate the values for "x" and "y" - - From the rectangular coordinates we calculate polar coordinates (theta and rho), correcting the theta value for the quadrant - - We evaluate the accuracy of calculations by plotting “x / y “ vs epoch and " theta / rho” vs epoch, adjusting the values to a linear fit and analyzing the R-squared value - We confirm the accuracy of the estimates for theta and rho with the residuals obtained from the ephemerids calculated and those of the CRE - -We calculate the calibration constants for each of the plates from Astrométrica +USNO A2. - -Relative astrometry is obtained for each pair with different astrometric reduction methods - -We evaluate and compare the results

O.A.N.L. Barcelona 2010 PAIRS SELECTION

O.A.N.L. Barcelona 2010 CATALOG CATALOG Catalog Rectilinear Elements v (1176 pairs)

O.A.N.L. Barcelona 2010 SELECTION CRITERIA - Pairs with Mag V>11 for both components. (61 Pairs = 5,2%) - Pairs with DEC between -20º y +20º. (15 Pairs = 1,3%) - Pairs with residuals <1º PA and < 0,5” Sep. (7 Pairs = 0,6%) - Pairs with rho >10”. (6 Pairs) - Pairs with historical measurements N >5. (6 Pairs)

O.A.N.L. Barcelona 2010 OBJECT PAIRS WDSIDR.A.DEC.NV1V2 CATALOG RECTILINEAR ELEMENTS EPHEMÉRIDS Épochtheta +/- rho +/ BAL , ,81311,1011, ,60,318,9730, BAL , ,6512,1512, ,80,711,8590, H N 1AC , ,4811,3611, ,10,230,3770, BAL , ,71011,3911, ,20,222,2850, HJ , ,1911,0911, ,30,614,6280, HJ , ,41211,3511, ,10,536,3710,277

O.A.N.L. Barcelona 2010 IMAGES

POSS II-J

O.A.N.L. Barcelona 2010 OBSERVATORY Anglo-Australian Observatory

O.A.N.L. Barcelona 2010 TELESCOPE UK Schmidt Telescope

O.A.N.L. Barcelona 2010 PLATES PLATES BAL 947STScI_POSS2UKSTU_Red_ _ BAL 781STScI_POSS2UKSTU_Red_ _ H N 1ACSTScI_POSS2UKSTU_Red_ _ BAL2891STScI_POSS2UKSTU_Red_ _ HJ 3102STScI_POSS2UKSTU_Red_ _ HJ 3220STScI_POSS2UKSTU_Red_ _

O.A.N.L. Barcelona 2010 STScI IMAGES BAL 781

O.A.N.L. Barcelona 2010 IMAGES ÉPOCH

O.A.N.L. Barcelona 2010 EPHEMERIDS CALCULATION EPHEMERIDS CALCULATION

O.A.N.L. Barcelona 2010 LINEAR ELEMENTS DDX0,,,,,,,,,XA,,,,,,,Y0,,,,,,,,,YA,,,,,,,T0,,,,,,RHO0,,,THETA0 +/-,,,,,,,,+/-,,,,,,+/-,,,,,,,,+/-,,,,,,+/-,,,,,+/-,,,,+/-,,, BAL BAL H N 1AC BAL HJ HJ

O.A.N.L. Barcelona 2010 COORD. TRANSFORMATION We calculate the rectangular coordinates replacing in: x = xa * (t-t0) + x0 y = ya * (t-t0) + y0 From “x y” we obtain the polar coordinates replacing in: rho = Raiz(x^2 + y^2) theta = arctg (-y/x) Starting from the linear elements: (x0,y0,t0) (rho0,theta0,t0)

O.A.N.L. Barcelona 2010 LINEAR REGRESSION BAL 947 Correction 270º Catalog Ephemerids thetarho Époch (T) xy theta rhothetarho O-C

O.A.N.L. Barcelona 2010 LINEAR FIT “x”

O.A.N.L. Barcelona 2010 LINEAR FIT “y”

O.A.N.L. Barcelona 2010 LINEAR FIT “theta”

O.A.N.L. Barcelona 2010 LINEAR FIT “rho”

O.A.N.L. Barcelona 2010 ESTIMATED EPHEMERIDS Époch (T) Ephemerids PlatesxythetaCorrection ºthetarho BAL BAL HN 1AC BAL HJ HJ

O.A.N.L. Barcelona 2010 CALIBRATION CONSTANTS CALIBRATION CONSTANTS

O.A.N.L. Barcelona :43:33 - USNO-A2.0: 154 Records read (22.8' x 22.8') Center Coordinates: RA = 00h 38m 24.00s, De = +01° 30' 00.0" Center Coordinates: RA = 00h 38m 24.00s, De = +01° 30' 00.0" 18:43:34 - Object List for Image 1 (BAL 947 STScI_POSS2UKSTU_Red_ _ ~1.fits): 753 Detections (75 Stars, 75 Ref. Stars, 0 Movers) 753 Detections (75 Stars, 75 Ref. Stars, 0 Movers) 18:43:34 - Astrometry of Image 1 (BAL 947 STScI_POSS2UKSTU_Red_ _ ~1.fits): 75 of 75 Reference Stars used: dRA = 0.36", dDe = 0.41" 75 of 75 Reference Stars used: dRA = 0.36", dDe = 0.41" X = E E-6*x' E-8*y' X = E E-6*x' E-8*y' Y = E E-8*x' E-6*y' Y = E E-8*x' E-6*y' Origin: x0 = 441.0, y0 = Origin: x0 = 441.0, y0 = Center Coordinates: RA = 00h 38m 23.96s, De = +01° 29' 59.2" Center Coordinates: RA = 00h 38m 23.96s, De = +01° 29' 59.2" Focal Length = mm, Rotation = 0.17° Focal Length = mm, Rotation = 0.17° Pixel Size: 1.02" x 1.02", Field of View: 15.0' x 15.0' Pixel Size: 1.02" x 1.02", Field of View: 15.0' x 15.0' 18:43:34 - Photometry of Image 1 (BAL 947 STScI_POSS2UKSTU_Red_ _ ~1.fits): 70 of 75 Reference Stars used: dmag = 0.41mag 70 of 75 Reference Stars used: dmag = 0.41mag CALIBRATION CONSTANTS

O.A.N.L. Barcelona 2010 CALIBRATION CONSTANTS Astrométrica + USNO-A2 AB A.Rotatión"/pixel R.A.DEC.R.A.DEC. BAL , BAL HN 1AC BAL HJ HJ ,

O.A.N.L. Barcelona 2010 ASTROMETRY ASTROMETRY

O.A.N.L. Barcelona 2010 ABSOLUTE ASTROMETRY Astrométrica + USNO A-2

O.A.N.L. Barcelona 2010 RecToPol

RecToPol EfeméridesRecToPolO-C thetarhothetarhothetarho BAL BAL HN 1AC BAL HJ HJ Desv. Estándar

O.A.N.L. Barcelona 2010 fv FITS VIEWER v 4.1.4

O.A.N.L. Barcelona 2010 fv FITS VIEWER v EfeméridesfvO-C thetarhothetarhothetarho BAL BAL HN 1AC BAL HJ HJ Desv Estándar

O.A.N.L. Barcelona 2010 ALADíN + “Dist”

O.A.N.L. Barcelona 2010 ALADíN + “Dist” EfeméridesAladínO-C thetarhothetarhothetarho BAL BAL HN 1AC BAL HJ HJ Desv Estándar

O.A.N.L. Barcelona 2010 REDUC & SURFACE

O.A.N.L. Barcelona 2010 REDUC EfeméridesReducO-C thetarhothetarhothetarho BAL BAL HN 1AC BAL HJ HJ Desv Estándar

O.A.N.L. Barcelona 2010 SURFACE EfeméridesSurfaceO-C thetarhothetarhothetarho BAL BAL HN 1AC BAL HJ HJ Desv Estándar

O.A.N.L. Barcelona 2010 RESULTS RESULTS

O.A.N.L. Barcelona 2010 O-C THETA RecToPolfvAladínReducSurface BAL BAL HN 1AC BAL HJ HJ

O.A.N.L. Barcelona 2010 O-C THETA

O.A.N.L. Barcelona 2010 O-C THETA (2)

O.A.N.L. Barcelona 2010 O-C RHO RecToPolfvAladínReducSurface BAL BAL HN 1AC BAL HJ HJ

O.A.N.L. Barcelona 2010 O-C RHO

O.A.N.L. Barcelona 2010 O-C RHO (2)

O.A.N.L. Barcelona 2010 STANDARD DEVIATION O-C THETA/RHO

O.A.N.L. Barcelona 2010 CONCLUSIONS The largest deviations correspond to the results obtained with "RecToPol" which almost certainly is due to the low precision of Astrometrica in estimating the centroid for star-saturated images. The largest deviations correspond to the results obtained with "RecToPol" which almost certainly is due to the low precision of Astrometrica in estimating the centroid for star-saturated images. Residuals derived from measurements made with the software "fv" are 10 times better than those obtained from the absolute astrometry and we can accept them within the error margins normally allowed. Residuals derived from measurements made with the software "fv" are 10 times better than those obtained from the absolute astrometry and we can accept them within the error margins normally allowed. The measurements made with "Surface" improve even those obtained with "fv" and show theta and rho residuals in the order of tenths. The measurements made with "Surface" improve even those obtained with "fv" and show theta and rho residuals in the order of tenths. The two softwares / methods that presents the lowest residuals between observed and calculated ephemerids (and therefore the greatest accuracy available) are “Reduc" and the tool "Dist" from Aladin. The two softwares / methods that presents the lowest residuals between observed and calculated ephemerids (and therefore the greatest accuracy available) are “Reduc" and the tool "Dist" from Aladin.

O.A.N.L. Barcelona 2010 THE REASON? THE REASON? We conclude that eye and brain working in concert, we always give more accurate results than any other synthetic method based on mathematical calculations. The high precision of “Reduc", similar to that achieved manually with "Dist", we are pretty sure that is due to the "human component " that we put into the software when we mark the photocentric star manually. We conclude that eye and brain working in concert, we always give more accurate results than any other synthetic method based on mathematical calculations. The high precision of “Reduc", similar to that achieved manually with "Dist", we are pretty sure that is due to the "human component " that we put into the software when we mark the photocentric star manually.

O.A.N.L. Barcelona 2010