Maintenance and Densification:

Maintenance and Densification: An Overview of Current Proper-Motion Catalogs - T. M. Girard (Yale University) Proper-Motion Catalogs

Importance of proper-motion surveys • Maintain the positional accuracy of an astrometric catalog with time • Provide a means of distance/luminosity estimation and thus discrimination between various classes of objects, (e.g., reduced proper motions) • Provide transverse velocity components, enabling study of the kinematics and equilibrium structure of various Galactic components, (i.e., thin disk, thick disk, halo) Proper-Motion Catalogs

Maintenance: Current astrometric catalogs... Proper-Motion Catalogs

Primary reference catalogs... Hipparcos (ESA 1997): defines ICRS in the optical ► 120,000 objects → ~3 /deg2, V < 7.5 ► @1991 typical epos = 1 mas; @2007 epos = 15 mas Tycho-2 (Høg et al. 2000): Hipparcos satellite starmapper & 1st-epoch ground-based positions ► 2.5x106 objects → 25 to 150 /deg2, V < 11.5 ► @2007 typical epos = 25 to 100 mas, depending on magnitude UCAC2 (Zacharias et al. 2004): USNO CCD Astrograph Catalog & 1st-epoch astrograph data/catalogs ► 48x106 objects, -90°< d <+40° to +52°; (soon to be all-sky, UCAC3) ►RUCAC< 16, ~85% complete; (to be improved, UCAC3) ►epos = 30 to 70 mas Proper-Motion Catalogs

< Some Currently Available Proper-Motion Catalogs “The Big Three” Proper-Motion Catalogs

< Some Currently Available Proper-Motion Catalogs (cont) Schmidt survey-based †from the CDS Description of Catalog I/305: “The GSC2.3 has no magnitude limit.” Proper-Motion Catalogs

< Some Currently Available Proper-Motion Catalogs (cont) Proper-motion threshold Rank merged Proper-Motion Catalogs

< Some Currently Available Proper-Motion Catalogs (cont) Other useful surveys Proper-Motion Catalogs

Detecting WD candidates in SDSS-USNOB1 (Kilic et al. 2005) Reduced Proper Motion Hg = g + 5logm + 5 Proper-Motion Catalogs

Detecting WD candidates in SDSS-USNOB1 (Harris et al. 2005) Proper-Motion Catalogs

Detecting WD candidates in SuperCOSMOS-RECONS (Finch et al. 2007) Proper-Motion Catalogs

Make certain your m’s are appropriate to the task at hand The central 2°x2° region of a sample southern-sky SPM field. The vector point diagram (VPD) constructed using proper motions from the USNO-B1 (left panel) is compared to that of the SPM3 (right panel) for stars in common. Note: The majority of the USNO-B1 proper motion values in this field are 0. Proper-Motion Catalogs

Magnitude Equation – the astrometrist’s bane A comparison of proper motions derived from uncorrected SPM blue-plate pairs and yellow-plate pairs indicates a significant magnitude equation is present. Using the grating images to correct each plate’s individual magnitude equation, the resulting proper motions are largely free of bias. SPM (and NPM) plates use objective gratings, producing diffraction image pairs which can be compared to the central-order image to deduce the form of the magnitude equation. Proper-Motion Catalogs

Velocity shear of the thick disk using SPM3 (Girard et al. 2006) ◄ SPM3 stars within 15° of SGP m’s measure transverse motion ► 2MASS photometry to select preferentially thick-disk giants ► Ngiants ~ 1200 Proper-Motion Catalogs

Velocity shear of the thick disk using SPM3 (cont.) Proper-motion data: Thick-disk component shows up well, distinct from the faint, nearby dwarfs that show a much larger m dispersion. ↓ Transverse Velocities Assume an absolute magnitude distribution as a function of J-K color to convert J,K,m to U,V,d. (Integrate under the assumed magnitude distributions.) Proper-Motion Catalogs

Velocity shear of the thick disk using SPM3 (cont.) ◄ Trim conservatively in U,V to eliminate nearby dwarfs. (Somewhat equivalent to separation using reduced proper motion.) Proper-Motion Catalogs

Velocity shear of the thick disk using SPM3 (cont.) Density and Velocity profiles: Over the range 1 < z < 4 kpc the observed sample shows an exponential form in number density and roughly linear forms of mean velocity and velocity dispersion as a function of z. BUT we must correct for systematic biases; (Malmquist and “Lutz-Kelker”-type). ►Use knowledge of our m uncertainties and selection criteria to construct Monte-Carlo simulations and derive the intrinsic Thick-disk parameters: hz = 783 ±48 pc dV/dz = -30 ±3 km/s/kpc dsV,U/dz = 9 ±3 km/s/kpc (and 8 ±6 % halo contamination). [ Figure Key: U-profiles in black, V in gray ] Proper-Motion Catalogs

Velocity shear of the thick disk using SPM3 (cont.) • Equilibrium analysis: • Assume a relaxed population of thick-disk stars in equilibrium within the gravitational potential of the Galaxy → • Jeans equation: • Test five model parameters: • Halo potential form; Plummer vs isothermal • Velocity-dispersion cross-term (<vRvz>) • Thick-disk radial scale-length (hR=3.5 – 5.0 kpc) • Form of the pressure term (self-gravitating or not) • Thin-disk mass surface density (36 – 48 M/pc2) Proper-Motion Catalogs

Velocity shear of the thick disk using SPM3 (cont.) Figure. The best-fit model’s intrinsic dispersion profile (dashed curve) is convolved with the sampling statistics and proper-motion errors to produce the ±1σ predicted “observed” profile (gray area). Heavy black curve is the actual observed profile for the SGP sample. Proper-Motion Catalogs

Velocity shear from low-mass dwarfs and SDSS-USNOB1 (Bochanski et al. 2007, astro-ph) ► Spectroscopic & proper-motion data for ~7400 K and M dwarfs, (l =105°, b = -62°) ► Well-sampled out to 1 kpc Bochanski et al. Figure 8. Velocity-dispersion profiles for thick-disk stars (squares) compared to the Besançon model prediction (crosses). Proper-Motion Catalogs

A cautionary word of advice... Dimitri Pourbaix (2007-10-15) “Someone’s garbage can be science for others.” The inverse can also be true! Proper-Motion Catalogs

Your catalog will be misused... Proper-Motion Catalogs

Maintenance and Densification: