IMPROVING GALACTIC CENTER ASTROMETRY BY REDUCING THE EFFECTS OF GEOMETRIC DISTORTION
By S. Yelda, Jessica R. Lu, A. Ghez, Will Clarkson, Jay Anderson, Tuan Do, K. Matthews. 2010
189 citations recorded by the source corpus.
We present significantly improved proper motion measurements of the Milky Way's central stellar cluster. These improvements are made possible by refining our astrometric reference frame with a new geometric optical distortion model for the W. M. Keck II 10 m telescope's adaptive optics camera (NIRC2) in its narrow field mode. For the first time, this distortion model is constructed from on-sky measurements and is made available to the public in the form of FITS files. When applied to widely dithered images, it produces residuals in the separations of stars that are a factor of ∼3 smaller compared with the outcome using previous models. By applying this new model, along with corrections for differential atmospheric refraction, to widely dithered images of SiO masers at the Galactic center (GC), we improve our ability to tie into the precisely measured radio Sgr A*-rest frame. The resulting infrared reference frame is ∼2–3 times more accurate and stable than earlier published efforts. In this reference frame, Sgr A* is localized to within a position of 0.6 mas and a velocity of 0.09 mas yr−1, or ∼3.4 km s−1 at 8 kpc (1σ). Also, proper motions for members of the central stellar cluster are more accurate, although less precise, due to the limited number of these wide field measurements. These proper motion measurements show that, with respect to Sgr A*, the central stellar cluster has no rotation in the plane of the sky to within 0.3 mas yr−1 arcsec−1, has no net translational motion with respect to Sgr A* to within 0.1 mas yr−1, and has net rotation perpendicular to the plane of the sky along the Galactic plane, as has previously been observed. While earlier proper motion studies defined a reference frame by assuming no net motion of the stellar cluster, this approach is fundamentally limited by the cluster's intrinsic dispersion and therefore will not improve with time. We define a reference frame with SiO masers and this reference frame's stability should improve steadily with future measurements of the SiO masers in this region (∝t−3/2). This is essential for achieving the necessary reference frame stability required to detect the effects of general relativity and extended mass on short-period stars at the GC.
Subfields: Astronomy and Astrophysics, Atomic and Molecular Physics, and Optics
View Paper: https://www.semanticscholar.org/paper/6c5b6cd5b8c4ccaa80afcbabbd9212f5b4870a64
How researchers see this paper
The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.
In Astronomy and Astrophysics
In Atomic and Molecular Physics, and Optics
Citations in the corpus
- A New Distortion Solution for NIRC2 on the Keck II Telescope (2016, methodology): “More than 90% of the pixels agree within 1σ; therefore, we measure no statistically significant differences between the Yelda et al. (2010) solution using imaging data from 2007 to 2009 and our pre-realignment solution.”
- Planet Hunters IX. KIC 8462852-where's the flux? (2015, methodology): “To correct for optical distortions in NIRC2, we used the calibration of Yelda et al. (2010).”
- ZODIACAL EXOPLANETS IN TIME (ZEIT). III. A SHORT-PERIOD PLANET ORBITING A PRE-MAIN-SEQUENCE STAR IN THE UPPER SCORPIUS OB ASSOCIATION (2016, methodology): “Each frame was linearized and corrected for geometric distortion using the NIRC2 solution from Yelda et al. (2010).”
- Adaptive Optics for Astronomy (2012, background): “…Davies & Kasper Ghez et al. 2008), shows that while the vast majority of stars in the central parsec are old and have randomly oriented orbits (Yelda et al. 2010), about half of the young stars in the central 10–15′′ are confined to a warped clockwise disk, while many of the remainder may…”
- THE IMPACT OF STELLAR MULTIPLICITY ON PLANETARY SYSTEMS. I. THE RUINOUS INFLUENCE OF CLOSE BINARY COMPANIONS (2016, methodology): “All observations used the smallest pixel scale (9.952± 0.002 mas pix−1; Yelda et al. 2010) and we corrected for geometric distortion using their NIRC2 distortion solution.”
- They are small worlds after all: revised properties of Kepler M dwarf stars and their planets (2015, methodology): “For each AO image we corrected for geometric distortion using the NIRC2 distortion solution from Yelda et al. (2010), flagged dead and hot pixels, and removed cosmic rays.”
- Individual Dynamical Masses of Ultracool Dwarfs (2017, methodology): “For NIRC2 narrow camera images obtained before 2015 April 13 UT, we use the astrometric solution of Yelda et al. (2010) to correct our measured (x, y) image coordinates for nonlinear optical distortion, using their derived pixel scale of 9.952 ± 0.002 mas pixel−1 and +0.”
- AN IMPROVED DISTANCE AND MASS ESTIMATE FOR SGR A* FROM A MULTISTAR ORBIT ANALYSIS (2016, methodology): “We tie the NIR measurements of these masers to astrometric and velocity measurements made in the radio to construct an absolute reference frame with Sgr A* at rest at the origin (see Reid et al. 2007; Ghez et al. 2008; Gillessen et al. 2009b; Yelda et al. 2010; Yelda et al. 2014).”
- PLANETS AROUND LOW-MASS STARS (PALMS). IV. THE OUTER ARCHITECTURE OF M DWARF PLANETARY SYSTEMS (2014, unknown): “Most of our imaging was carried out with the narrow camera, which has a plate scale of 9.952 ± 0.002 mas pix−1 (Yelda et al. 2010) and provides Nyquist sampling at the diffraction limit beyond ∼1.2 µm.”
- CHARACTERIZING K2 PLANET DISCOVERIES: A SUPER-EARTH TRANSITING THE BRIGHT K DWARF HIP 116454 (2014, methodology): “We corrected the data for optical aberrations using the distortion solution from B. Cameron (2007, priv. communication) and North-aligned the images using the detector orientation measured by Yelda et al. (2010).”