DOCSLIB.ORG

Exploration of the Kuiper Belt by High-Precision Photometric Stellar Occultations: First Results F

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read 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. Pau,1 N. Peixinho,1,10 and G. P. Tozzi11 Received 2005 November 11; accepted 2006 May 4 ABSTRACT We report here the first detection of hectometer-size objects by the method of serendipitous stellar occultation. This method consists of recording the diffraction shadow created when an object crosses the observer’s line of sight and occults the disk of a background star. One of our detections is most consistent with an object between Saturn and Uranus. The two other diffraction patterns detected are caused by Kuiper Belt objects beyond 100 AU from the Sun and hence are the farthest known objects in the solar system. These detections show that the Kuiper Belt is much more extended than previously believed and that the outer part of the disk could be composed of smaller objects than the inner part. This gives critical clues to understanding the problem of the formation of the outer planets of the solar system. Key words: Kuiper Belt — occultations — solar system: formation 1. INTRODUCTION exhibit an almost continuous size distribution from kilometer- to 5 m scale objects. Extrapolating the size distribution of the known The Kuiper Belt is the remnant of the circumsolar disk where KBOs down to objects of 1 km radius leads to 1011 KBOs with a the giant planets of the solar system formed 4.6 billion years ago. total mass of only 0.1 Mo (Gladman et al. 2001). In contrast, a Since 1992 more than 1000 Kuiper Belt objects (KBOs) have been simple extrapolation of the surface mass density of the solar sys- detected, mostly outside Neptune’s orbit. Three classes of objects tem outside 35 AU yields several Earth masses. Moreover, KBO are observed: the Plutinos are, like Pluto, in resonant orbit with accretion models require an initial Kuiper Belt 100 times more Neptune, the classical objects have moderately inclined and eccen- massive than the currently observed belt and predict that smaller tric orbits, and the scattered disk objects, like the recently discov- ered 2003 UB , have large eccentricities and large inclinations. objects of the primitive Kuiper Belt could have been collisionally 313 depleted over the age of the solar system (Malhotra et al. 2000). This structure is explained by perturbations by the planets and The outer limit of the belt is also unknown, but beyond 48 AU in particular by resonances with Neptune (Levison & Morbidelli there does appear to be a sharp decline in the number of objects 2003). However, the distance of the belt currently limits the di- exceeding 40 km (Allen et al. 2002). rect detection of KBOs to those with sizes greater than a few tens Stellar occultations are a common technique used to study un- of kilometers and closer than 100 AU. seen bodies in the solar system, planetary atmospheres, and rings Several facts lead to the idea that the known KBOs (>10 km (Sicardy et al. 1991; Millis et al. 1987). The method consists of diameter) represent only a small fraction of the Kuiper Belt pop- recording the luminous flux of a star with a fast photometer or a ulation. Triton’s crater distribution suggests that small impactors rapid CCD camera. A dip in the stellar light is detected when an (kilometer and subkilometer) have recently riddled this moon (Stern & McKinnon 2000), and so the Kuiper Belt must contain many occulting object passes between the observer and the star. This method is able to detect small objects inaccessible to direct obser- such bodies. Various collisional simulations reported (Farinella vation. For example, a star with 1 as of angular size has a projected et al. 2000) argue in favor of a significant population of small KBOs. The near-Earth asteroids (NEAs; Rabinowitz et al. 2000) size comparable to a 30 m object at 40 AU. Detailed computations (Roques et al. 1987; Roques & Moncuquet 2000), which include diffraction effects, have shown the potential of occultation to de- 1 Laboratoire d’Etudes Spatiales et d’Instrumentation en Astrophysique, tect small objects orbiting in the outer solar system, and in par- Observatoire de Paris, F-92195 Meudon Principal Cedex, France; francoise ticular beyond the orbit of Neptune. The use of occultations to [email protected]. understand the KBO population has already been suggested in 2 Corresponding author. Bailey (1976), Brown & Websters (1997), and Cooray & Farmer 3 Department of Physics and Astronomy, University of Sheffield, Sheffield S10 2TN, UK. (2003), and the Taiwan-American Occultation Survey (Chen 2002) 4 Department of Physics, University of Warwick, Coventry CV4 7AL, UK. experiment will automatically monitor thousands of stars to search 5 National Research Council of Canada, Victoria, BC V9E 2E9, Canada. for occultations by intervening KBOs. 6 Department of Physics and Astronomy, McMaster University, Hamilton, ON L8S 4M1, Canada. 2. PRINCIPLE OF THE OCCULTATION TECHNIQUE 7 Astronomical Observatory of Kharkiv National University, 61022 Kharkiv, Ukraine. The principle of stellar occultation is to record the stellar flux 8 School of Mathematics and Physics, Queens University Belfast, Belfast during the transit of an occulting object. Occultation by a KBO is BT7 1NN, Northern Ireland, UK. a rapid phenomenon involving Fresnel diffraction. The detection 9 Observatoire de Besanc¸on, BP 1615, 25010 Besanc¸on Cedex, France. of KBOs by occultation depends on various parameters. 10 Grupo de Astrofı´sicada, Universidade de Coimbra and Observato´rio de Coimbra, Largo D. Dinis, 3001-454 Coimbra, Portugal. The direction of observation modifies the transverse velocity v À1/2 11 Istituto Nazionale di Astrofisica, Osservatorio Astrofisico di Arcetri, Largo of the KBO with respect to the star: v ¼ vE½cos (!) À R , Enrico Fermi 5, I-50125 Florence, Italy. where vE is the Earth’s velocity, ! is the angle from opposition to 819 820 ROQUES ET AL. Vol. 132 TABLE 1 Characteristics of the Occulted Stars V Apparent Radius at 40 AU Ecliptic Longitude Ecliptic Latitude Field Star (mag) B À V (m) (deg) (deg) Field 1 ................................ TYC 281-906 12.10 À0.28 <100 183.5 +2.9 TYC 281-864 12.15 À0.16 <250 183.5 +2.9 Field 2 ................................ TYC 6172-1103 11.81 À0.04 <270 227.0 À0.4 TYC 6172-1154 12.70 À0.27 <90 227.0 À0.4 Field 3 ................................ TYC 6821-1317 12.25 À0.41 <100 254.8 À7.1 TYC 6821 1425 12.40 À0.32 <100 254.8 À7.1 Notes.—The apparent radius is deduced from the visual magnitude and the spectral class (B À V ). This is a maximum value since the reddening has not been taken into account. the line of sight, and R is the radius of the KBO’s orbit in AU. ing two main-sequence O stars of approximately equal brightness, The probability of occultation is proportional to v, but the occul- selected from the Tycho catalogue (Hog et al. 2000; Table 1). tation’s duration is inversely proportional to this velocity. At oppo- The stars were chosen to ensure a small angular diameter, which sition, the velocity and the occultation rate are maximum, but the is a prerequisite to obtain diffraction fringes. A total of 1.9 mil- occultation duration is minimum. At quadrature, defined by cos lion frames were obtained on the nights of 2004 April 29 and (!) ¼ RÀ1/2, the velocity of the KBO is minimum. May 2, simultaneously in the g0 (0.48 m) and i0 (0.77 m) Sloan The angular size of the star is a critical parameter because the Digital Sky Survey filters (Fukugita et al. 1996). occultation profile is smoothed over the stellar disk. A stellar radius of 1 mas corresponds to a projected radius at 40 AU of 30 km. 3.2. Data Reduction Occultation of such stars by a subkilometer KBO does not gen- Data reduction was carried out using the ULTRACAM pipe- erate a detectable decrease of the stellar flux. Consequently, the line data reduction software. After debiasing and flat-fielding the search for small objects needs carefully chosen target stars. They images, source fluxes were extracted by summing the counts in a must have a small angular diameter but be bright enough to give circular aperture centered on each target star and subtracting a a good signal-to-noise (S/N) ratio.
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]
  • 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]
  • 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.
    [Show full text]