DOCSLIB.ORG

High Precision Astrometry of Occultation Asteroids

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
High Precision Astrometry of Occultation Asteroids High Precision Astrometry of Occultation Asteroids Allan Alonzo-Ault Stephanie Toole Dr. William M. Owen, Jr. - Mentor Jet Propulsion Laboratory Table Mountain Observatory Purpose ● Image Main Belt and Trojan Asteroids ● Update Ephemeris ● Predict Occultations ● Characterize Asteroids Ephemeris A table or data file giving the calculated positions of a celestial object at regular intervals throughout a period. Source: Oxford Dictionaries Occultation The interruption of the light from a celestial body or of the signals from a spacecraft by the intervention of a celestial body; especially : an eclipse of a star or planet by the moon. (Asteroids in our case) Source: Merriam-Webster Dictionary Occultation Event ● Antiope, a binary asteroid in the outer main belt! ● Each colored line is a separate observation. ● Image consists of approximately 50 different observations of event. ● Helps determine shape and size of asteroid. On Location: Table Mountain Observatory ● Wrightwood, CA ● Elevation 7500 ft. ● Est. 1925 by Smithsonian Inst. ● JPL arrived 1961 ● Atmospheric Monitoring ● Optical Communication ● Asteroid Tracking Every Telescope Needs A Home ● TM-12 ● Temperature Controlled ● Remote Access is Possible from JPL Eyes on the Prize ● Astro ● f/16 Mechanics ● German ● 0.6 m Equatorial ● Ritchey - Mount Chrétien ● 9500mm reflector Focal Length ● Installed in 1966 Your Humble Observers A Picture Is Worth 16.8 Million Pixels ● ProLine PL16803 ● 4096 x 4096 Pixels ● 9µm Pixel Size ● 36.8 x 36.8 mm Sensor ● Monochrome ● Thermo-Electric Cooling to 55℃ below ambient Predicting our Targets ● ● Prior to arrival at TMO ● Trajectory Geometry Program (TGP) ● GhostView ● Three updates per night to pinpoint target location near local meridian. ● Criteria: ○ Declination angle > -30° ○ The more stars the better! Our Workspace ● Programs to control the dome, telescope and camera. Focus On The Task Ahead ● Use the Position Client to choose a star. ● Astrometric Catalog lists stars near the Zenith to minimize atmospheric distortion. ● Choose the faintest star on the list. FOCUS! ● 10 second exposures of the star. ● Goal is to obtain the sharpest light profile of the star. ● Once satisfied with focus, center the star and calibrate telescope. Controlling The Telescope ● Position Client ● Telescope Control Program ● Paddle Client ● RA / Dec of ● Moves Telescope to the ● Manually Target Desired Position Adjust for Calibration Imaging ● 2 to 3 images of each target, depending on star field. ● Offset in different directions to capture different background stars. ● 3 minute exposures. Calibration Field ● M11: The Wild Duck Cluster. ● Done each night of imaging. ● 5 different offsets, one centered, one towards each corner. ● Used in data reduction to calibrate position of images. Captain’s Log ● Point file keeps track of RA and Dec of every image taken. ● Temp file keeps track of Temperature, Pressure and Humidity at the time each target is imaged. ● TMO Weather Station Data. Challenges to Making Good Observations ● Clouds ● Turbulent Atmosphere ● High Humidity ● Telescope Out of Focus ● Smoke!!! Mistakes Were Made ● Telescope cover closed. ● Targets observed on the wrong night. ● Pointing errors. Data Reduction We image ~50 targets per night, but only publish one line of data per target. Least Squares Method We solve directly for changes in RA and Dec of the telescope and the stars. We also solve for a rotation angle, the focal length and the aspect ratio of the pixels. Then we add in the 2nd through 5th order terms using products of Legendre polynomials. Why Legendre? They have the nice property that if the stars are uniformly distributed, the solution for each one will not be statistically correlated with the others. Put another way, they're orthonormal: if you integrate the product of two of them over [-1, +1] you get zero if they're of different order. Why Reduce? ● it turns the pixels into RA and declination in the sky ● Gives us more information about the image ● Catches errors Mostly Autonomous Data Reduction ● The linux based command scripts that Dr. Owen wrote for the data reduction are extremely powerful ● They can almost autonomously reduce the data ● We step in to fix our own errors, help with centroiding for faint targets, and delete the “bad stuff” Two (or Three) is Better Than One For our data reduction technique to work, we need at least two different images of the target. Why? ● By taking two or three images of our target with different pointing, you get information about the telescope distortions by seeing how star patterns change in each image Calibration Field We used the A calibration M11, Wild field tells us Duck Cluster, how the as our telescope and calibration field camera are because it behaving that contains about night. 2900 stars. The point file records where the telescope is pointed for each image. The temp file records the temperature, barometric pressure, and humidity. doit This script calls on four other scripts: Prepare Amptemp Centroid Reduce reduce TGP (trajectory geometry program): provides coordinates for predicted stars or the target asteroid AMP: list of the observations with identified targets and with positions for all the targets, catalogued and uncatalogued stars found AOPG and ADAP: calculates expected (x,y) coordinates of images which are subtracted from observed (x,y) coordinates, which lead to the residuals. Calculates partial derivatives of the coordinates using the variables for determining (x,y). ADAP processes this and makes summary files, doing mathematical calculations. Check ● Checks to see if the number of targets and pictures equals the number of targets located in the images Xrover ● If a target is not found we use a program called Xrover to manually locate the target findbad ● Supplies a list of images with “bad residuals” ● A bad residual is anything bigger than one pixel ADAP ● We delete the stars with bad residuals by commenting them out in their input file ● The input file is read by ADAP (Astrometric Data Analysis Program) Reduce, rinse, repeat We continue with the same steps until arriving here. deliver This script condenses the summary files as produced by the adap script. A file is created in emacs that we edit to credit observers and measurers. This file gets sent to the Minor Planet Center, to a few people in the occultation community and to a few people at JPL whose job is to update the orbits of the planets and their satellites. cleanup Problems and Issues ● Xrover does not like number lock, and we do not know why ● Adap files do not like being wider than 80 characters, because that is how many characters can fit on an IBM punch card ● You must be in the correct directory ● Emacs is the text editor we use, if you search for a file in the wrong directory it will not tell you that you are wrong Our Results ● 678 images taken. ● 145 unique objects imaged. ● 519 positions obtained. ● 7 successful deliveries to the Minor Planets Center. Not Just Asteroids ● Updated the positions of 6 of Saturn’s satellites. ● Titan, Rhea, Tethys, Hyperion, Dione and Iapetus. ● Failed to do the same for Mars’ satellites, Phobos and Deimos. ● Attempted on 3 different nights near opposition. Failed Occultation Event ● Asteroid 1015 Christa ● 60% probability of TMO being in the occultation path. ● No success this night. ● Friday July 13, 2018! Acknowledgements This project was completed at NASA’s Jet Propulsion Laboratory in Pasadena, CA and Table Mountain Observatory in Wrightwood, CA. This work was supported by NSF grant #AST-1460538 to Los Angeles City College. We would like to thank our mentor at JPL, Dr. William M. Owen Jr., CURE Coordinators Paul McCudden and Derrick Kiley at Los Angeles City College, JPL Program Coordinator Roslyn Soto, Heath Rhoades and the entire support staff at Table Mountain Observatory..
Load more

Recommended publications
  • Surface Characteristics of Transneptunian Objects and Centaurs from Photometry and Spectroscopy
    Barucci et al.: Surface Characteristics of TNOs and Centaurs 647 Surface Characteristics of Transneptunian Objects and Centaurs from Photometry and Spectroscopy M. A. Barucci and A. Doressoundiram Observatoire de Paris D. P. Cruikshank NASA Ames Research Center The external region of the solar system contains a vast population of small icy bodies, be- lieved to be remnants from the accretion of the planets. The transneptunian objects (TNOs) and Centaurs (located between Jupiter and Neptune) are probably made of the most primitive and thermally unprocessed materials of the known solar system. Although the study of these objects has rapidly evolved in the past few years, especially from dynamical and theoretical points of view, studies of the physical and chemical properties of the TNO population are still limited by the faintness of these objects. The basic properties of these objects, including infor- mation on their dimensions and rotation periods, are presented, with emphasis on their diver- sity and the possible characteristics of their surfaces. 1. INTRODUCTION cally with even the largest telescopes. The physical char- acteristics of Centaurs and TNOs are still in a rather early Transneptunian objects (TNOs), also known as Kuiper stage of investigation. Advances in instrumentation on tele- belt objects (KBOs) and Edgeworth-Kuiper belt objects scopes of 6- to 10-m aperture have enabled spectroscopic (EKBOs), are presumed to be remnants of the solar nebula studies of an increasing number of these objects, and signifi- that have survived over the age of the solar system. The cant progress is slowly being made. connection of the short-period comets (P < 200 yr) of low We describe here photometric and spectroscopic studies orbital inclination and the transneptunian population of pri- of TNOs and the emerging results.
    [Show full text]
  • Exploration of the Kuiper Belt by High-Precision Photometric Stellar Occultations: First Results F
    Exploration of the Kuiper Belt by High-Precision Photometric Stellar Occultations: First Results F. Roques, A. Doressoundiram, V. Dhillon, T. Marsh, S. Bickerton, J. J. Kavelaars, M. Moncuquet, M. Auvergne, I. Belskaya, M. Chevreton, et al. To cite this version: F. Roques, A. Doressoundiram, V. Dhillon, T. Marsh, S. Bickerton, et al.. Exploration of the Kuiper Belt by High-Precision Photometric Stellar Occultations: First Results. Astronomical Journal, Amer- ican Astronomical Society, 2006, 132, pp.819-822. 10.1086/505623. hal-00640050 HAL Id: hal-00640050 https://hal.archives-ouvertes.fr/hal-00640050 Submitted on 10 Nov 2011 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. The Astronomical Journal, 132:819Y822, 2006 August # 2006. The American Astronomical Society. All rights reserved. Printed in U.S.A. EXPLORATION OF THE KUIPER BELT BY HIGH-PRECISION PHOTOMETRIC STELLAR OCCULTATIONS: FIRST RESULTS F. Roques,1,2 A. Doressoundiram,1 V. Dhillon,3 T. Marsh,4 S. Bickerton,5,6 J. J. Kavelaars,5 M. Moncuquet,1 M. Auvergne,1 I. Belskaya,7 M. Chevreton,1 F. Colas,1 A. Fernandez,1 A. Fitzsimmons,8 J. Lecacheux,1 O. Mousis,9 S.
    [Show full text]
  • March 21–25, 2016
    FORTY-SEVENTH LUNAR AND PLANETARY SCIENCE CONFERENCE PROGRAM OF TECHNICAL SESSIONS MARCH 21–25, 2016 The Woodlands Waterway Marriott Hotel and Convention Center The Woodlands, Texas INSTITUTIONAL SUPPORT Universities Space Research Association Lunar and Planetary Institute National Aeronautics and Space Administration CONFERENCE CO-CHAIRS Stephen Mackwell, Lunar and Planetary Institute Eileen Stansbery, NASA Johnson Space Center PROGRAM COMMITTEE CHAIRS David Draper, NASA Johnson Space Center Walter Kiefer, Lunar and Planetary Institute PROGRAM COMMITTEE P. Doug Archer, NASA Johnson Space Center Nicolas LeCorvec, Lunar and Planetary Institute Katherine Bermingham, University of Maryland Yo Matsubara, Smithsonian Institute Janice Bishop, SETI and NASA Ames Research Center Francis McCubbin, NASA Johnson Space Center Jeremy Boyce, University of California, Los Angeles Andrew Needham, Carnegie Institution of Washington Lisa Danielson, NASA Johnson Space Center Lan-Anh Nguyen, NASA Johnson Space Center Deepak Dhingra, University of Idaho Paul Niles, NASA Johnson Space Center Stephen Elardo, Carnegie Institution of Washington Dorothy Oehler, NASA Johnson Space Center Marc Fries, NASA Johnson Space Center D. Alex Patthoff, Jet Propulsion Laboratory Cyrena Goodrich, Lunar and Planetary Institute Elizabeth Rampe, Aerodyne Industries, Jacobs JETS at John Gruener, NASA Johnson Space Center NASA Johnson Space Center Justin Hagerty, U.S. Geological Survey Carol Raymond, Jet Propulsion Laboratory Lindsay Hays, Jet Propulsion Laboratory Paul Schenk,
    [Show full text]
  • Abstracts of the 50Th DDA Meeting (Boulder, CO)
    Abstracts of the 50th DDA Meeting (Boulder, CO) American Astronomical Society June, 2019 100 — Dynamics on Asteroids break-up event around a Lagrange point. 100.01 — Simulations of a Synthetic Eurybates 100.02 — High-Fidelity Testing of Binary Asteroid Collisional Family Formation with Applications to 1999 KW4 Timothy Holt1; David Nesvorny2; Jonathan Horner1; Alex B. Davis1; Daniel Scheeres1 Rachel King1; Brad Carter1; Leigh Brookshaw1 1 Aerospace Engineering Sciences, University of Colorado Boulder 1 Centre for Astrophysics, University of Southern Queensland (Boulder, Colorado, United States) (Longmont, Colorado, United States) 2 Southwest Research Institute (Boulder, Connecticut, United The commonly accepted formation process for asym- States) metric binary asteroids is the spin up and eventual fission of rubble pile asteroids as proposed by Walsh, Of the six recognized collisional families in the Jo- Richardson and Michel (Walsh et al., Nature 2008) vian Trojan swarms, the Eurybates family is the and Scheeres (Scheeres, Icarus 2007). In this theory largest, with over 200 recognized members. Located a rubble pile asteroid is spun up by YORP until it around the Jovian L4 Lagrange point, librations of reaches a critical spin rate and experiences a mass the members make this family an interesting study shedding event forming a close, low-eccentricity in orbital dynamics. The Jovian Trojans are thought satellite. Further work by Jacobson and Scheeres to have been captured during an early period of in- used a planar, two-ellipsoid model to analyze the stability in the Solar system. The parent body of the evolutionary pathways of such a formation event family, 3548 Eurybates is one of the targets for the from the moment the bodies initially fission (Jacob- LUCY spacecraft, and our work will provide a dy- son and Scheeres, Icarus 2011).
    [Show full text]
  • Appulses of Jupiter and Saturn
    IN ORIGINAL FORM PUBLISHED IN: arXiv:(side label) [physics.pop-ph] Sternzeit 46, No. 1+2 / 2021 (ISSN: 0721-8168) Date: 6th May 2021 Appulses of Jupiter and Saturn Joachim Gripp, Emil Khalisi Sternzeit e.V., Kiel and Heidelberg, Germany e-mail: gripp or khalisi ...[at]sternzeit-online[dot]de Abstract. The latest conjunction of Jupiter and Saturn occurred at an optical distance of 6 arc minutes on 21 December 2020. We re-analysed all encounters of these two planets between -1000 and +3000 CE, as the extraordinary ones (< 10′) take place near the line of nodes every 400 years. An occultation of their discs did not and will not happen within the historical time span of ±5,000 years around now. When viewed from Neptune though, there will be an occultation in 2046. Keywords: Jupiter-Saturn conjunction, Appulse, Trigon, Occultation. Introduction reason is due to Earth’s orbit: while Jupiter and Saturn are locked in a 5:2-mean motion resonance, the Earth does not The slowest naked-eye planets Jupiter and Saturn made an join in. For very long periods there could be some period- impressive encounter in December 2020. Their approaches icity, however, secular effects destroy a cycle, e.g. rotation have been termed “Great Conjunctions” in former times of the apsides and changes in eccentricity such that we are and they happen regularly every ≈20 years. Before the left with some kind of “semi-periodicity”. discovery of the outer ice giants these classical planets rendered the longest known cycle. The separation at the instant of conjunction varies up to 1 degree of arc, but the Close Encounters latest meeting was particularly tight since the planets stood Most pass-bys of Jupiter and Saturn are not very spectac- closer than at any other occasion for as long as 400 years.
    [Show full text]
  • ASTEROID OCCULTATIONOCCULTATION OBSERVINGOBSERVING (And Recording) ~ a Basic Introduction ~
    ASTEROIDASTEROID OCCULTATIONOCCULTATION OBSERVINGOBSERVING (and recording) ~ A basic introduction ~ Most amateur astronomers look forward to observing eclipses – a nice lunar eclipse, and the all-too- rare solar variety. Some travel for hundreds of miles to “catch the shadow”. ...But did you know there are potential eclipses to observe nearly every clear night? There are ---- Asteroid Occultations. What's an asteroid occultation? Assuming you know what an asteroid is.... There are now just over 1 MILLION asteroids that have published orbits. Over 500,000 of them have orbits that are established well enough that they have been “numbered” (in general, the lower the number, the more refined the orbit). There are also billions of stars visible thru a telescope in the night sky. It's only inevitable that at times the alignment will be just right for these chunks of rock in space to pass in front of the absolute pinpoint light from stars. If you are in just the right place on Earth, the asteroid will “eclipse” the star, blocking out its light for anywhere from a fraction of a second, to up to 10's of seconds. As the star is essentially infinitely far away – as compared to the distance to the asteroid – the “shadow” the asteroid casts on Earth is basically the size of the asteroid. This shadow moves across the surface of the Earth in a narrow band (the width of which is the diameter of the asteroid), often crossing thousands of miles of the Earth's surface. If you are located somewhere in this narrow band, and it's clear out, you can see the star “blink out”, and then back - an asteroid occultation.
    [Show full text]
  • Near-Infrared Mapping and Physical Properties of the Dwarf-Planet Ceres
    A&A 478, 235–244 (2008) Astronomy DOI: 10.1051/0004-6361:20078166 & c ESO 2008 Astrophysics Near-infrared mapping and physical properties of the dwarf-planet Ceres B. Carry1,2,C.Dumas1,3,, M. Fulchignoni2, W. J. Merline4, J. Berthier5, D. Hestroffer5,T.Fusco6,andP.Tamblyn4 1 ESO, Alonso de Córdova 3107, Vitacura, Santiago de Chile, Chile e-mail: [email protected] 2 LESIA, Observatoire de Paris-Meudon, 5 place Jules Janssen, 92190 Meudon Cedex, France 3 NASA/JPL, MS 183-501, 4800 Oak Grove Drive, Pasadena, CA 91109-8099, USA 4 SwRI, 1050 Walnut St. # 300, Boulder, CO 80302, USA 5 IMCCE, Observatoire de Paris, CNRS, 77 Av. Denfert Rochereau, 75014 Paris, France 6 ONERA, BP 72, 923222 Châtillon Cedex, France Received 26 June 2007 / Accepted 6 November 2007 ABSTRACT Aims. We study the physical characteristics (shape, dimensions, spin axis direction, albedo maps, mineralogy) of the dwarf-planet Ceres based on high angular-resolution near-infrared observations. Methods. We analyze adaptive optics J/H/K imaging observations of Ceres performed at Keck II Observatory in September 2002 with an equivalent spatial resolution of ∼50 km. The spectral behavior of the main geological features present on Ceres is compared with laboratory samples. Results. Ceres’ shape can be described by an oblate spheroid (a = b = 479.7 ± 2.3km,c = 444.4 ± 2.1 km) with EQJ2000.0 spin α = ◦ ± ◦ δ =+ ◦ ± ◦ . +0.000 10 vector coordinates 0 288 5 and 0 66 5 . Ceres sidereal period is measured to be 9 074 10−0.000 14 h. We image surface features with diameters in the 50–180 km range and an albedo contrast of ∼6% with respect to the average Ceres albedo.
    [Show full text]
  • Precise Astrometry and Diameters of Asteroids from Occultations – a Data-Set of Observations and Their Interpretation
    MNRAS 000,1–22 (2020) Preprint 14 October 2020 Compiled using MNRAS LATEX style file v3.0 Precise astrometry and diameters of asteroids from occultations – a data-set of observations and their interpretation David Herald 1¢, David Gault2, Robert Anderson3, David Dunham4, Eric Frappa5, Tsutomu Hayamizu6, Steve Kerr7, Kazuhisa Miyashita8, John Moore9, Hristo Pavlov10, Steve Preston11, John Talbot12, Brad Timerson (deceased)13 1Trans Tasman Occultation Alliance, [email protected] 2Trans Tasman Occultation Alliance, [email protected] 3International Occultation Timing Association, [email protected] 4International Occultation Timing Association, [email protected] 5Euraster, [email protected] 6Japanese Occultation Information Network, [email protected] 7Trans Tasman Occultation Alliance, [email protected] 8Japanese Occultation Information Network, [email protected] 9International Occultation Timing Association, [email protected] 10International Occultation Timing Association – European Section, [email protected] 11International Occultation Timing Association, [email protected] 12Trans Tasman Occultation Alliance, [email protected] 13International Occultation Timing Association, deceased Accepted XXX. Received YYY; in original form ZZZ ABSTRACT Occultations of stars by asteroids have been observed since 1961, increasing from a very small number to now over 500 annually. We have created and regularly maintain a growing data-set of more than 5,000 observed asteroidal occultations. The data-set includes: the raw observations; astrometry at the 1 mas level based on centre of mass or figure (not illumination); where possible the asteroid’s diameter to 5 km or better, and fits to shape models; the separation and diameters of asteroidal satellites; and double star discoveries with typical separations being in the tens of mas or less.
    [Show full text]
  • Dwarf Planet Ceres: Ellipsoid Dimensions and Rotational Pole from Keck and VLT Adaptive Optics Images Q ⇑ J.D
    Icarus 236 (2014) 28–37 Contents lists available at ScienceDirect Icarus journal homepage: www.elsevier.com/locate/icarus Dwarf planet Ceres: Ellipsoid dimensions and rotational pole from Keck and VLT adaptive optics images q ⇑ J.D. Drummond a, , B. Carry b, W.J. Merline c, C. Dumas d, H. Hammel e, S. Erard f, A. Conrad g, P. Tamblyn c, C.R. Chapman c a Starfire Optical Range, Directed Energy Directorate, Air Force Research Laboratory, Kirtland AFB, NM 87117-577, USA b IMCCE, Observatoire de Paris, CNRS, 77 av. Denfert Rochereau, 75014 Paris, France c Southwest Research Institute, 1050 Walnut St. # 300, Boulder, CO 80302, USA d ESO, Alonso de Córdova 3107, Vitacura, Casilla 19001, Santiago de Chile, Chile e AURA, 1200 New York Ave. NW, Suite 350, Washington, DC 20005, USA f LESIA, Observatoire de Paris, CNRS, UPMC, Université Paris-Diderot, 5 place Jules Janssen, 92195 Meudon, France g Max-Planck-Institut fuer Astronomie, Koenigstuhl 17, D-69117 Heidelberg, Germany article info abstract Article history: The dwarf planet (1) Ceres, the largest object between Mars and Jupiter, is the target of the NASA Dawn Received 7 December 2013 mission, and we seek a comprehensive description of the spin-axis orientation and dimensions of Ceres in Revised 13 March 2014 order to support the early science operations at the rendezvous in 2015. We have obtained high-angular Accepted 14 March 2014 resolution images using adaptive optics cameras at the W.M. Keck Observatory and the ESO VLT over ten Available online 5 April 2014 dates between 2001 and 2010, confirming that the shape of Ceres is well described by an oblate spheroid.
    [Show full text]
  • The Taiwan-America Occultation Survey for Kuiper Belt Objects Sun
    Small-Telescope Astronomy on Global Scales ASP Conference Series, Vol. 246, 2001 W.P. Chen, C. Lemme, B. Paczyriski The Taiwan-America Occultation Survey for Kuiper Belt Objects Sun-Kun King1 Institute of Astronomy and Astrophysics, Academia Sinica, P.O. Box 1-87, Nankang, Taipei, Taiwan 115, R.O.C. Abstract. The purpose of the TAOS project is to directly measure the number of Kuiper Belt Objects (KBOs) down to the typical size of come- tary nuclei (a few km). In contrast to the direct detection of reflected light from a KBO by a large telescope where its brightness falls off roughly as the fourth power of its distance to the sun, an occultation survey relies on the light from the background stars thus is much less sensitive to that distance. The probability of such occultation events is so low that we will need to conduct 100 billion measurements per year in order to detect the ten to four thousand occultation events expected. Three small (20 inch), fast (f/1.9), wide-field (3 square degrees) robotic telescopes, equipped with a 2,048 x 2,048 CCD camera, are being deployed in central Taiwan. They will automatically monitor 3,000 stars every clear night for several years and operate in a coincidence mode so that the sequence and timing of a possible occultation event can be distinguished from false alarms. More telescopes on a north-south baseline so as to measure the size of an occultating KBO may be later added into the telescope array. We also anticipate a lot of byproducts on stellar astronomy based on the large amount (10,000 giga-bytes/year) of photometry data to be generated by TAOS.
    [Show full text]
  • Shallow Ultraviolet Transits of WD 1145+017
    Shallow Ultraviolet Transits of WD 1145+017 Item Type Article Authors Xu, Siyi; Hallakoun, Na’ama; Gary, Bruce; Dalba, Paul A.; Debes, John; Dufour, Patrick; Fortin-Archambault, Maude; Fukui, Akihiko; Jura, Michael A.; Klein, Beth; Kusakabe, Nobuhiko; Muirhead, Philip S.; Narita, Norio; Steele, Amy; Su, Kate Y. L.; Vanderburg, Andrew; Watanabe, Noriharu; Zhan, Zhuchang; Zuckerman, Ben Citation Siyi Xu et al 2019 AJ 157 255 DOI 10.3847/1538-3881/ab1b36 Publisher IOP PUBLISHING LTD Journal ASTRONOMICAL JOURNAL Rights Copyright © 2019. The American Astronomical Society. All rights reserved. Download date 09/10/2021 04:17:12 Item License http://rightsstatements.org/vocab/InC/1.0/ Version Final published version Link to Item http://hdl.handle.net/10150/634682 The Astronomical Journal, 157:255 (12pp), 2019 June https://doi.org/10.3847/1538-3881/ab1b36 © 2019. The American Astronomical Society. All rights reserved. Shallow Ultraviolet Transits of WD 1145+017 Siyi Xu (许偲艺)1 ,Na’ama Hallakoun2 , Bruce Gary3 , Paul A. Dalba4 , John Debes5 , Patrick Dufour6, Maude Fortin-Archambault6, Akihiko Fukui7,8 , Michael A. Jura9,21, Beth Klein9 , Nobuhiko Kusakabe10, Philip S. Muirhead11 , Norio Narita (成田憲保)8,10,12,13,14 , Amy Steele15, Kate Y. L. Su16 , Andrew Vanderburg17 , Noriharu Watanabe18,19, Zhuchang Zhan (詹筑畅)20 , and Ben Zuckerman9 1 Gemini Observatory, 670 N. A’ohoku Place, Hilo, HI 96720, USA; [email protected] 2 School of Physics and Astronomy, Tel-Aviv University, Tel-Aviv 6997801, Israel 3 Hereford Arizona Observatory, Hereford, AZ 85615, USA
    [Show full text]
  • STAR OCCULTATION MEASUREMENTS \, Lrd
    ') STAR OCCULTATION MEASUREMENTS \, Lrd. AS AN AID TO NAVIGATION IN ~ *·~J C IS-LUNAR SPACE by ROY VINCENT KEENAN S.B., University of Nebraska (1957) JOHN DONALD REGENHARDT S.B., United States Naval Academy (1957) SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE at the MASSACHUSETTS INSTITUTE OF TECHNOLOGY June, 1962 Signature of Authors iptlrtment of eronautics and Astronautics, June 1961 Certified by_ Thesis Supei- e. Accepted by Chairman, Departmental Graduate Committee dTisd- f - a-proed , or iru- • c ... " '. .. : .. '' " S c ,.. ;i*f,· 7, r- " ' '" II G i ii STAR OCCULTATION MEASUREMENTS AS AN AID TO NAVIGATION IN CIS-LUNAR SPACE by Roy V. Keenan John D. Regenhardt Submitted to the Department of Aeronautics and Astronautics on May 19, 1962 in partial fulfillment of the requirements for the degree of Master of Science. ABSTRACT The time measurement of star occultations is one of several modes of obtaining navigation data in cis-lunar space. Using statistical methods of optimization of data, the feasibility of navigation using the measurement of star occultations as a method in itself and in combination with angle measure- ments is investigated using digital computation techniques. The real star field is approximated by a statistical star back- ground for the purpose of this study. An "average occultation frequency" is calculated based on a reference trajectory and the statistical star background. The occurrence or non- occurrence of occultations along the trajectory is determined by a random number operation which utilizes the "average occultation frequency". The measurements obtained are introduced into a navigation routine which simulates the circumlunar voyage.
    [Show full text]