A New Distortion Solution for NIRC2 on the Keck II Telescope

We present a new geometric distortion model for the narrow-field mode of the near-infrared camera (NIRC2) fed by the adaptive optics system on the W. M. Keck II telescope. The adaptive optics system and NIRC2 camera were realigned on 2015 April 13. Observations of the crowded globular cluster, M53, were obtained before and after the realignment to characterize the geometric field distortion. The distorted NIRC2 positions of M53 stars were compared with precise astrometry of this cluster from Hubble Space Telescope observations. The resulting distortion map constructed just before the realignment is consistent with the previous solution derived using data from 2007 to 2009, indicating that the distortion has been stable to ∼0.5 mas. The distortion map changed significantly after a realignment of 4.5 mas (75%) rms, and the new distortion model for post-realignment observations have a total accuracy of ∼1.1 mas.

[1]  Gautam Vasisht,et al.  ASTROMETRIC CONFIRMATION AND PRELIMINARY ORBITAL PARAMETERS OF THE YOUNG EXOPLANET 51 ERIDANI b WITH THE GEMINI PLANET IMAGER , 2015, 1509.07514.

[2]  A. Thirouin,et al.  The mutual orbit, mass, and density of the large transneptunian binary system Varda and Ilmarë , 2015, 1505.00510.

[3]  R. Romani,et al.  CHARACTERIZATION OF THE INNER KNOT OF THE CRAB: THE SITE OF THE GAMMA-RAY FLARES? , 2015, 1504.04613.

[4]  C. Baranec,et al.  RECONNAISSANCE OF THE HR 8799 EXOSOLAR SYSTEM. II. ASTROMETRY AND ORBITAL MOTION , 2014, 1409.6388.

[5]  I. Ivans,et al.  MEASURING CONSISTENT MASSES FOR 25 MILKY WAY GLOBULAR CLUSTERS , 2014, 1411.1763.

[6]  Michael C. Liu,et al.  NEW EVIDENCE FOR A SUBSTELLAR LUMINOSITY PROBLEM: DYNAMICAL MASS FOR THE BROWN DWARF BINARY Gl 417BC , 2014, 1406.1184.

[7]  Jessica R. Lu,et al.  PROPERTIES OF THE REMNANT CLOCKWISE DISK OF YOUNG STARS IN THE GALACTIC CENTER , 2014, 1401.7354.

[8]  N. V. Kharchenko,et al.  Global survey of star clusters in the Milky Way II. The catalogue of basic parameters , 2013, 1308.5822.

[9]  Jessica R. Lu,et al.  The Shortest-Known–Period Star Orbiting Our Galaxy’s Supermassive Black Hole , 2012, Science.

[10]  Jessica R. Lu,et al.  PROPER MOTIONS OF THE ARCHES CLUSTER WITH KECK LASER GUIDE STAR ADAPTIVE OPTICS: THE FIRST KINEMATIC MASS MEASUREMENT OF THE ARCHES , 2011, 1112.5458.

[11]  J. Anderson,et al.  IMPROVING GALACTIC CENTER ASTROMETRY BY REDUCING THE EFFECTS OF GEOMETRIC DISTORTION , 2010, 1010.0064.

[12]  S. Trippe,et al.  EVIDENCE FOR WARPED DISKS OF YOUNG STARS IN THE GALACTIC CENTER , 2008, 0811.3903.

[13]  Jessica R. Lu,et al.  A DISK OF YOUNG STARS AT THE GALACTIC CENTER AS DETERMINED BY INDIVIDUAL STELLAR ORBITS , 2008, 0808.3818.

[14]  Michael J. Ireland,et al.  Keck Laser Guide Star Adaptive Optics Monitoring of 2MASS J15344984–2952274AB: First Dynamical Mass Determination of a Binary T Dwarf , 2008, 0807.0238.

[15]  Giampaolo Piotto,et al.  THE ACS SURVEY OF GLOBULAR CLUSTERS. V. GENERATING A COMPREHENSIVE STAR CATALOG FOR EACH CLUSTER , 2008 .

[16]  Jessica R. Lu,et al.  The Proper Motion of the Arches Cluster with Keck Laser-Guide Star Adaptive Optics , 2007, 0706.4133.

[17]  Calibration of ACS/WFC Absolute Scale and Rotation for Use in Creation of a JWST Astrometric Reference Field , 2007 .

[18]  P. B. Cameron,et al.  Near-Infrared and X-Ray Observations of the Enigmatic G70.7+1.2 , 2007, 0704.2415.

[19]  Jay Anderson.  Variation of the Distortion Solution of the WFC , 2007 .

[20]  Jay Anderson,et al.  PSFs, Photometry, and Astronomy for the ACS/WFC , 2006 .

[21]  T. Paumard,et al.  The Two Young Star Disks in the Central Parsec of the Galaxy: Properties, Dynamics, and Formation , 2006, astro-ph/0601268.

[22]  B. Macintosh,et al.  Measuring the Mass of a Pre-Main-Sequence Binary Star through the Orbit of TWA 5A , 2005, astro-ph/0701551.

[23]  Jessica R. Lu,et al.  Stellar Orbits around the Galactic Center Black Hole , 2003, astro-ph/0306130.

[24]  D. Rouan,et al.  The Stellar Cusp around the Supermassive Black Hole in the Galactic Center , 2003, astro-ph/0305423.

[25]  Laird M. Close,et al.  Analysis of isoplanatic high resolution stellar fields by the StarFinder code , 2000 .

[26]  R. Hook,et al.  Drizzle: A Method for the Linear Reconstruction of Undersampled Images , 1998, astro-ph/9808087.

[27]  E. Becklin,et al.  High Proper-Motion Stars in the Vicinity of Sagittarius A*: Evidence for a Supermassive Black Hole at the Center of Our Galaxy , 1998, astro-ph/9807210.

[28]  D. Tytler,et al.  Differential Atmospheric Refraction and Limitations on the Relative Astrometric Accuracy of Large Telescopes , 1998 .

[29]  Andrea M. Ghez,et al.  High Proper Motion Stars in the Vicinity of SGR A*: Evidence for a Supermassive Black Hole at the Center of Our Galaxy , 1998 .

[30]  Reinhard Genzel,et al.  Stellar proper motions in the central 0.1 PC of the galaxy , 1997 .