James N. Heasley

Efficient intra-and inter-night linking of asteroid detections using kd-trees

Abstract The Panoramic Survey Telescope and Rapid Response System (Pan-STARRS) under development at the University of Hawaiis Institute for Astronomy is creating the first fully automated end-to-end Moving Object Processing System (MOPS) in the world. It will be capable of identifying detections of moving objects in our solar system and linking those detections within and between nights, attributing those detections to known objects, calculating initial and differentially corrected orbits for linked detections, precovering detections when they exist, and orbit identification. Here we describe new kd-tree and variable-tree algorithms that allow fast, efficient, scalable linking of intra and inter-night detections. Using a pseudo-realistic simulation of the Pan-STARRS survey strategy incorporating weather, astrometric accuracy and false detections we have achieved nearly 100% efficiency and accuracy for intra-night linking and nearly 100% efficiency for inter-night linking within a lunation. At realistic sky-plane densities for both real and false detections the intra-night linking of detections into ‘tracks’ currently has an accuracy of 0.3%. Successful tests of the MOPS on real source detections from the Spacewatch asteroid survey indicate that the MOPS is capable of identifying asteroids in real data.

Restored methane band images of Uranus and Neptune

Abstract Charge-coupled device images of Uranus and Neptune taken in the 8900-A absorption band of methane are presented. The images have been digitally processed by means of nonlinear deconvolution techniques to partially remove the effects of atmospheric seeing. The restored Uranus images show strong limb brightening consistent with previous observations and theoretical models of the planets atmosphere. The computer-processed images of Neptune show discreted cloud features similar to those reported previously by B. A. Smith, H. J. Reitsema and S. M. Larson (1979 Bull. Amer. Astron. Soc. 11 , 570). A time series of the restored Neptune images shows a continuous variation which may be due to the planets rotation.

Fourier Analysis of Hubble Space Telescope Fine Guidance Sensor Data of Binary Stars and Application to the Multiple System HD 157948

A Fourier-based method is presented for the analysis of binary and multiple star data taken with the Hubble Space Telescope Fine Guidance Sensors (FGSs). Relative astrometry and magnitude differences are obtained as with standard FGS analysis techniques, and although the FGS system is essentially unfiltered, this method also permits the characterization of color differences between components of binary or multiple star systems based on the wavelength dependence of the interference fringes produced by the instrument. Using the multiple system HD 157948, we show that the method produces astrometric and photometric measurements that are consistent with previous FGS analysis for the three components that lie within the field of view of FGS and gives color differences relative to the primary for two of the three known companions. Speckle observations of the system with the WIYN 3.5 m telescope at Kitt Peak National Observatory are also presented, which, in combination with the FGS results and other data available in the literature, permit B - V colors and absolute V magnitudes to be obtained of all four components in the system. Their colors and magnitudes are plotted on the H-R diagram, and a comparison with theoretical isochrones indicates that the results are consistent with theory for a relatively young, somewhat metal-poor system.

The distribution of dust in the inner coma of comet IRAS-Araki-Alcock (1983d)

Abstract High-resolution images of comet IRAS-Araki-Alcock taken on five separate through its closest approach to the Earth are presented. The images were taken in the red and near-infrared, and so consist primarily of continuum scattering from dust grains. The distribution of dust in the inner coma varied widely from day to day, although the dust was emitted primarily in the sunward direction on all days. The main emission exhibited a lag angle consistent with a nuclear rotational vector that was oriented approximately along the line of sight on May 11.3 1983 UT. A curved filament, extending in the sunward direction, was seen in the deepest images obtained on this day as well, and the azimuthal distribution of dust was strongly of dust was strongly peakeed in the sunward direction. The presence of the curved filament is indicative of dust outflow from an active region, on a mantled nucleus. On all days, the brightness falls off slower than the r − expected for uniform outflow, which is interpreted as resulting from fragmentation of the dust grains as they traveled through the coma. The nuclear region appeared stellar on all days. The seeing-limited spatial resolutions was 19 km on May 11.3, but deconvolution of the images with the instrumental profile enables an upper limit of 17 km to be placed on the diameter of the nucleus.

Pan-STARRS: A Large Synoptic Survey Telescope Array

The IFA and collaborators are embarking on a project to develop a 4-telescope synoptic survey instrument. While somewhat smaller than the 6.5m class telescope envisaged by the decadal review in their proposal for a LSST, this facility will nonetheless be able to accomplish many of the LSST science goals. In this paper we will describe the motivation for a distributed aperture approach for the LSST, the current concept for Pan-STARRS -- a pilot project for the LSST proper -- and its performance goals and science reach. We will also discuss how the facility may be expanded.