DOCSLIB.ORG

Journal of the Association of Lunar & Planetary Observers

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Journal of the Association of Lunar & Planetary Observers ISSN-0039-2502 Journal of the Association of Lunar & Planetary Observers The Strolling Astronomer Volume 60, Number 3, Summer 2018 Now in Portable Document Format (PDF) for Macintosh and PC-compatible computers Online and in COLOR at http://www.alpo-astronomy.org Soft, wispy Venus . (see page 2 for details) The Strolling Astronomer Journal of the Inside the ALPO Association of Lunar & Point of View The Future of Lunar Observing ...........2 News of General Interest ..........................................3 Planetary Observers Our Cover: Beautiful, Soft and Wispy Venus .......3 Another ALPO Member Honored by the IAU .......3 The Strolling Astronomer ALPO Annual Conference ...................................3 Jupiter Section Staff Changes .............................3 Volume 60, No.3, Summer 2018 Call for JALPO Papers .........................................4 This issue published in June 2018 for distribution in both portable ALPO Interest Section Reports .................................4 document format (pdf) and hardcopy format. ALPO Observing Section Reports ............................6 Letter to the Editor ..................................................22 This publication is the official journal of the Association of Lunar & Notable Deaths .......................................................22 Planetary Observers (ALPO). ALPO Member, Staffer Fr. Ken Delvano ............22 Comet Discover Tom Bopp ................................23 The purpose of this journal is to share observation reports, opinions, and other news from ALPO members with other members and the Papers & Presentations professional astronomical community. Index to Volume 56 (2014) of © 2018, Association of Lunar and Planetary Observers (ALPO). The The Strolling Astronomer ......................................25 ALPO hereby grants permission to educators, academic libraries and Terms and Abbreviations Used In This Report .......29 the professional astronomical community to photocopy material for A Report on Carrington Rotations 2199 educational or research purposes as required. There is no charge for through 2201 (2017 12 30.9382 to these uses provided that credit is given to The Strolling Astronomer, 2018 03 22.9368) .................................................29 the “JALPO” or the ALPO itself. All others must request permission ALPO Observations of Venus During the from the ALPO. 2014 Western (Morning) Apparition .....................41 ALPO Observations of Jupiter For membership or general information about the ALPO, contact: During the 2014-2015 Apparition .........................53 Galilean Satellite Eclipse Timings: Matthew Will The 2010-2011 Apparition ....................................75 ALPO Membership Secretary/Treasurer ALPO Observations of the Remote Planets P.O. Box 13456 in 2016-2017 ........................................................79 Springfield, Illinois 62791-3456 ALPO Resources E-mail to: [email protected] Board of Directors ...................................................85 Publications Section ...............................................85 Visit the ALPO online at: Interest Sections .....................................................85 http://www.alpo-astronomy.org Observing Sections .................................................85 ALPO Publications ..................................................86 The Monograph Series ...........................................86 ALPO Observing Section Publications ...................87 Back Issues of The Strolling Astronomer ................88 Volume 60, No. 3, Summer 2018 Page 1 The Strolling Astronomer Inside the ALPO Member, section and activity news Association of Lunar & Planetary Observers (ALPO) Point of View The Future of Lunar Observing Board of Directors By Wayne Bailey, ALPO Lunar Topographical Studies Program Executive Director (Chair); Richard W. Schmude, Jr. coordinator Associate Director; Julius L. Benton, Jr. Member of the Board; Sanjay Limaye Why observe the Moon? It's the only Member of the Board; Michael D. Reynolds celestial object that humans have Member of the Board; Ken Poshedly actually visited. It has no rapidly Member of the Board; John E. Westfall changing atmospheric phenomena to Member of the Board & Secretary/Treasurer; watch. There are no seasonally Matthew Will changing surface features. Lunar Founder/Director Emeritus; the late Walter H. Haas orbiting spacecraft have mapped the surface in exquisite detail. What is left Publications for the amateur to do? Isn't the Moon just a nice, bright, easy-to-find object Editor & Publisher: Ken Poshedly that's fine for beginners to start with before moving on to more difficult and Primary Observing Section & Interest Section worthy objects? These are all comments that I've heard at various Staff times, and all are correct, but not the complete story. (See full listing in ALPO Resources) The Moon is an excellent object to develop observing Lunar& Planetary Training Section: techniques. Because the Moon is so close, even the poorest first Timothy J. Robertson observation typically will reveal some features, and Solar Section: Rik Hill improvements in observing skill produce obvious results. The Mercury Section: Frank Melillo best results, however, require just as much skill as for any other Venus Section: Julius L. Benton, Jr. object, and continuously changing lighting conditions provide Mercury/Venus Transit Section: John E. Westfall ever-changing views. Lunar Section: Lunar Topographical Studies & While even the best observations can't match the resolution of spacecraft images, one of the amateur's advantages is the Selected Areas Program; Wayne Bailey flexibility to observe a feature any time it is sunlit. In orbit, the Lunar Meteoritic Impact Search; Brian Cudnik observing schedule and lighting are determined by orbital Lunar Transient Phenomena; Anthony Cook dynamics. The existence of details worth examining in the Mars Section: Roger Venable spacecraft data may only become apparent under very specific Minor Planets Section: Frederick Pilcher lighting conditions. The online spacecraft data is currently under- Jupiter Section: Richard Schmude utilized by amateurs in this regard. Albedo features, such as Saturn Section: Julius L. Benton, Jr. rays, and their changes with phase are still best studied from Remote Planets Section: Richard W. Schmude, Jr. Earth rather than lunar orbit because of the constraints of orbital Eclipse Section: Michael D. Reynolds dynamics. Comets Section: Carl Hergenrother Meteors Section: Robert D. Lunsford Amateur observations are primarily wide-band digital images, with a small number of visual observations. Few observers use Meteorites Section: Dolores Hill filters other than to improve seeing. But photometric imaging ALPO Online Section: Larry Owens with the use of standard filters offers prospects for new Computing Section: Larry Owens observing projects. And lunar spectroscopy is an unexplored Youth Section: Timothy J. Robertson field for amateurs. However, solid state spectral features are typically broad, and mostly in the infrared, so spectroscopy may not offer any advantage over photometry. Finally, polarimetry is (Go to “The Future of Lunar Observing” on page 23) Page 2 Volume 60, No. 3, Summer 2018 The Strolling Astronomer Inside the ALPO Member, section and activity news News of General Interest Our Cover: Beautiful, Soft and Wispy Venus Our cover this time features an image of a planet that’s known for showing very little of itself. Yet, it is rather beautiful with what it does show. Taken by William Schrantz of Nicholasville, KY, on June 23, 2009 Robert Garfinkle and IAU certificate for Minor Planet at 10:50 UT, employing a 25.4 cm “(31862) Garfinkle”. (10.0 in.) Newtonian reflector, this representative UV image of Venus shows the characteristic roughly horizontal V, Y, or ψ (psi)-shaped major axis equal to 2.3765297 AU Robertson and conference dusky cloud features in the and an eccentricity of 0.1379013, coordinator Robert K. Buchheim. atmosphere of Venus typically inclined by 8.64812° with respect to More information here: https:// depicted in good quality images at the ecliptic. soundcloud.com/observersnotebook/ UV wavelengths in good seeing the-observers-notebook-the-2018-joint- conditions. ALPO Annual Conference conference-with-the-sas-and-the-alpo Other bright regions and amorphous We received late confirmation that dusky features are also captured in this year’s ALPO annual conference Jupiter Section Staff Changes this image. will be a joint meeting with the Effective immediately, Richard Society for Astronomical Sciences Venus is 58.4% illuminated at visual Schmude is once more coordinator Thursday through Saturday, June 14 magnitude -4.2 with an apparent of the ALPO Jupiter Section and is through 16, in Ontario, California. diameter of 20.0". South is at the top also coordinator of the Jupiter of the image. Details and contact information can Section Galilean Satellites Eclipse be found on the inside front cover of Observing program. Another ALPO Member this Journal. Please note that the These changes come following Honored by the IAU deadline for submitting abstracts for decisions by Ed Grafton to step down papers to be presented will have Our collective congratulations go to as section coordinator for health passed by the time you see this ALPO Book Review Editor Robert reasons and by John Westfall to turn notice. If you are interested in Garfinkle as planet 2000 EY70 has the Galilean satellite program over to presenting a paper,
Load more

Recommended publications
  • Small Bodies of the Solar System Don Yeomans
    news and views teakre Small bodies of the Solar System Don Yeomans ,-.......-..-.- "_.."..._..".."....".._..I........... ".........._ "_.""".." ".......... " "............_..._.." ....".."-..- ..-.... "....""... Discoveries of comets that behave like asteroids and asteroids that behave like comets are making us reassess our view of Earth's smallest neighbours. cientists have a strong urge to place Mother Nature's objects into neat Sboxes. For most of the past halfcentury, the comets and asteroids of the Solar System did seem to belong in two separate popula- tions -each within their own box. The rules werethatcomets,withawiderangeoforbits, were solid, dirty iceballs originating in the so-called Oort cloud at theedge of the Solar System. Asteroids were definedas bitsofrock anfimed mostly to a region between Mars and Jupiter and travelling roughly in the same plane and inthe same direction as the planets about theSun (Fig. 1).Fromtjme to Lime over the past 50 years, objects were bund that did not really belong in either )OX, but they were onlyconsidered as occa- iional exceptions to the rules. Within the Figure 1 The usual view of corneta and utcroida. The inna Soh System cuntlinr the Sun and the ,ast few years, however,Mother Nature has four terreatrid planar:Mercury, Venu%Euth and Ma.fie lump of mdc that make up thenuin ticked over the boxes entirely, spilling the asteroid bdt between him and Jupiterorbit the Sun in the meplane andthe medirection PJ the :ontents and demanding thatscientists rec- planets. Most tometa have highly dlipticnl orbits, whichmeans they spend most of their timein the )gnizE crossover objects - asteroids that outer reache of the Solar System with only briefpasages dose to the Sun.
    [Show full text]
  • The Comet's Tale
    THE COMET’S TALE Journal of the Comet Section of the British Astronomical Association Number 33, 2014 January Not the Comet of the Century 2013 R1 (Lovejoy) imaged by Damian Peach on 2013 December 24 using 106mm F5. STL-11k. LRGB. L: 7x2mins. RGB: 1x2mins. Today’s images of bright binocular comets rival drawings of Great Comets of the nineteenth century. Rather predictably the expected comet of the century Contents failed to materialise, however several of the other comets mentioned in the last issue, together with the Comet Section contacts 2 additional surprise shown above, put on good From the Director 2 appearances. 2011 L4 (PanSTARRS), 2012 F6 From the Secretary 3 (Lemmon), 2012 S1 (ISON) and 2013 R1 (Lovejoy) all Tales from the past 5 th became brighter than 6 magnitude and 2P/Encke, 2012 RAS meeting report 6 K5 (LINEAR), 2012 L2 (LINEAR), 2012 T5 (Bressi), Comet Section meeting report 9 2012 V2 (LINEAR), 2012 X1 (LINEAR), and 2013 V3 SPA meeting - Rob McNaught 13 (Nevski) were all binocular objects. Whether 2014 will Professional tales 14 bring such riches remains to be seen, but three comets The Legacy of Comet Hunters 16 are predicted to come within binocular range and we Project Alcock update 21 can hope for some new discoveries. We should get Review of observations 23 some spectacular close-up images of 67P/Churyumov- Prospects for 2014 44 Gerasimenko from the Rosetta spacecraft. BAA COMET SECTION NEWSLETTER 2 THE COMET’S TALE Comet Section contacts Director: Jonathan Shanklin, 11 City Road, CAMBRIDGE. CB1 1DP England. Phone: (+44) (0)1223 571250 (H) or (+44) (0)1223 221482 (W) Fax: (+44) (0)1223 221279 (W) E-Mail: [email protected] or [email protected] WWW page : http://www.ast.cam.ac.uk/~jds/ Assistant Director (Observations): Guy Hurst, 16 Westminster Close, Kempshott Rise, BASINGSTOKE, Hampshire.
    [Show full text]
  • King David's Altar in Jerusalem Dated by the Bright Appearance of Comet
    Annals of Archaeology Volume 1, Issue 1, 2018, PP 30-37 King David’s Altar in Jerusalem Dated by the Bright Appearance of Comet Encke in 964 BC Göran Henriksson Department of Physics and Astronomy, Uppsala University, Box 516, SE 751 20 Uppsala, Sweden *Corresponding Author: Göran Henriksson, Department of Physics and Astronomy, Uppsala University, Box 516, SE 751 20 Uppsala, [email protected] ABSTRACT At the time corresponding to our end of May and beginning of June in 964 BC a bright comet with a very long tail dominated the night sky of the northern hemisphere. It was Comet Encke that was very bright during the Bronze Age, but today it is scarcely visible to the naked eye. It first appeared as a small comet close to the zenith, but for every night it became greater and brighter and moved slowly to the north with its tail pointing southwards. In the first week of June the tail was stretched out across the whole sky and at midnight it was visible close to the meridian. In this paper the author wishes to test the hypothesis that this appearance of Comet Encke corresponds to the motion in the sky above Jerusalem of “the sword of the Angel of the Lord”, mentioned in 1 Chronicles, in the Old Testament. Encke was first circumpolar and finally set at the northern horizon on 8 June in 964 BC at 22. This happened according to the historical chronology between 965 and 960 BC. The calculations of the orbit of Comet Encke have been performed by a computer program developed by the author.
    [Show full text]
  • Ice & Stone 2020
    Ice & Stone 2020 WEEK 17: APRIL 19-25, 2020 Presented by The Earthrise Institute # 17 Authored by Alan Hale This week in history APRIL 19 20 21 22 23 24 25 APRIL 20, 1910: Comet 1P/Halley passes through perihelion at a heliocentric distance of 0.587 AU. Halley’s 1910 return, which is described in a previous “Special Topics” presentation, was quite favorable, with a close approach to Earth (0.15 AU) and the exhibiting of the longest cometary tail ever recorded. APRIL 20, 2025: NASA’s Lucy mission is scheduled to pass by the main belt asteroid (52246) Donaldjohanson. Lucy is discussed in a previous “Special Topics” presentation. APRIL 19 20 21 22 23 24 25 APRIL 21, 2024: Comet 12P/Pons-Brooks is predicted to pass through perihelion at a heliocentric distance of 0.781 AU. This comet, with a discussion of its viewing prospects for 2024, is a previous “Comet of the Week.” APRIL 19 20 21 22 23 24 25 APRIL 22, 2020: The annual Lyrid meteor shower should be at its peak. Normally this shower is fairly weak, with a peak rate of not much more than 10 meteors per hour, but has been known to exhibit significantly stronger activity on occasion. The moon is at its “new” phase on April 23 this year and thus the viewing circumstances are very good. COVER IMAGE CREDIT: Front and back cover: This artist’s conception shows how families of asteroids are created. Over the history of our solar system, catastrophic collisions between asteroids located in the belt between Mars and Jupiter have formed families of objects on similar orbits around the sun.
    [Show full text]
  • Symposium on Telescope Science
    Proceedings for the 26th Annual Conference of the Society for Astronomical Sciences Symposium on Telescope Science Editors: Brian D. Warner Jerry Foote David A. Kenyon Dale Mais May 22-24, 2007 Northwoods Resort, Big Bear Lake, CA Reprints of Papers Distribution of reprints of papers by any author of a given paper, either before or after the publication of the proceedings is allowed under the following guidelines. 1. The copyright remains with the author(s). 2. Under no circumstances may anyone other than the author(s) of a paper distribute a reprint without the express written permission of all author(s) of the paper. 3. Limited excerpts may be used in a review of the reprint as long as the inclusion of the excerpts is NOT used to make or imply an endorsement by the Society for Astronomical Sciences of any product or service. Notice The preceding “Reprint of Papers” supersedes the one that appeared in the original print version Disclaimer The acceptance of a paper for the SAS proceedings can not be used to imply or infer an endorsement by the Society for Astronomical Sciences of any product, service, or method mentioned in the paper. Published by the Society for Astronomical Sciences, Inc. First printed: May 2007 ISBN: 0-9714693-6-9 Table of Contents Table of Contents PREFACE 7 CONFERENCE SPONSORS 9 Submitted Papers THE OLIN EGGEN PROJECT ARNE HENDEN 13 AMATEUR AND PROFESSIONAL ASTRONOMER COLLABORATION EXOPLANET RESEARCH PROGRAMS AND TECHNIQUES RON BISSINGER 17 EXOPLANET OBSERVING TIPS BRUCE L. GARY 23 STUDY OF CEPHEID VARIABLES AS A JOINT SPECTROSCOPY PROJECT THOMAS C.
    [Show full text]
  • Aqueous Alteration on Main Belt Primitive Asteroids: Results from Visible Spectroscopy1
    Aqueous alteration on main belt primitive asteroids: results from visible spectroscopy1 S. Fornasier1,2, C. Lantz1,2, M.A. Barucci1, M. Lazzarin3 1 LESIA, Observatoire de Paris, CNRS, UPMC Univ Paris 06, Univ. Paris Diderot, 5 Place J. Janssen, 92195 Meudon Pricipal Cedex, France 2 Univ. Paris Diderot, Sorbonne Paris Cit´e, 4 rue Elsa Morante, 75205 Paris Cedex 13 3 Department of Physics and Astronomy of the University of Padova, Via Marzolo 8 35131 Padova, Italy Submitted to Icarus: November 2013, accepted on 28 January 2014 e-mail: [email protected]; fax: +33145077144; phone: +33145077746 Manuscript pages: 38; Figures: 13 ; Tables: 5 Running head: Aqueous alteration on primitive asteroids Send correspondence to: Sonia Fornasier LESIA-Observatoire de Paris arXiv:1402.0175v1 [astro-ph.EP] 2 Feb 2014 Batiment 17 5, Place Jules Janssen 92195 Meudon Cedex France e-mail: [email protected] 1Based on observations carried out at the European Southern Observatory (ESO), La Silla, Chile, ESO proposals 062.S-0173 and 064.S-0205 (PI M. Lazzarin) Preprint submitted to Elsevier September 27, 2018 fax: +33145077144 phone: +33145077746 2 Aqueous alteration on main belt primitive asteroids: results from visible spectroscopy1 S. Fornasier1,2, C. Lantz1,2, M.A. Barucci1, M. Lazzarin3 Abstract This work focuses on the study of the aqueous alteration process which acted in the main belt and produced hydrated minerals on the altered asteroids. Hydrated minerals have been found mainly on Mars surface, on main belt primitive asteroids and possibly also on few TNOs. These materials have been produced by hydration of pristine anhydrous silicates during the aqueous alteration process, that, to be active, needed the presence of liquid water under low temperature conditions (below 320 K) to chemically alter the minerals.
    [Show full text]
  • The Minor Planet Bulletin
    THE MINOR PLANET BULLETIN OF THE MINOR PLANETS SECTION OF THE BULLETIN ASSOCIATION OF LUNAR AND PLANETARY OBSERVERS VOLUME 38, NUMBER 2, A.D. 2011 APRIL-JUNE 71. LIGHTCURVES OF 10452 ZUEV, (14657) 1998 YU27, AND (15700) 1987 QD Gary A. Vander Haagen Stonegate Observatory, 825 Stonegate Road Ann Arbor, MI 48103 [email protected] (Received: 28 October) Lightcurve observations and analysis revealed the following periods and amplitudes for three asteroids: 10452 Zuev, 9.724 ± 0.002 h, 0.38 ± 0.03 mag; (14657) 1998 YU27, 15.43 ± 0.03 h, 0.21 ± 0.05 mag; and (15700) 1987 QD, 9.71 ± 0.02 h, 0.16 ± 0.05 mag. Photometric data of three asteroids were collected using a 0.43- meter PlaneWave f/6.8 corrected Dall-Kirkham astrograph, a SBIG ST-10XME camera, and V-filter at Stonegate Observatory. The camera was binned 2x2 with a resulting image scale of 0.95 arc- seconds per pixel. Image exposures were 120 seconds at –15C. Candidates for analysis were selected using the MPO2011 Asteroid Viewing Guide and all photometric data were obtained and analyzed using MPO Canopus (Bdw Publishing, 2010). Published asteroid lightcurve data were reviewed in the Asteroid Lightcurve Database (LCDB; Warner et al., 2009). The magnitudes in the plots (Y-axis) are not sky (catalog) values but differentials from the average sky magnitude of the set of comparisons. The value in the Y-axis label, “alpha”, is the solar phase angle at the time of the first set of observations. All data were corrected to this phase angle using G = 0.15, unless otherwise stated.
    [Show full text]
  • Southwest Florida Astronomical Society SWFAS the Eyepiece
    Southwest Florida Astronomical Society SWFAS The Eyepiece February 2017 Contents: Message from the President .............................................................................. Page 1 Program this Month ......................................................................................... Page 2 Photos by Chuck and Matthew ........................................................................... Page 2 In the Sky this Month ...................................................................................... Page 3 Future Events ................................................................................................. Page 4 Bright Comet Prospects for 2017 ........................................................................ Page 6 Comet Campaign: Amateurs Wanted? ................................................................ Page 14 Club Officers & Positions .................................................................................. Page 16 A MESSAGE FROM THE PRESIDENT I hope everyone is having a good new year. We are now into our heaviest period for public events. On the 11th we have STEMtastic/Edison Day of Discovery downtown. On the 25th we will be at Rotary Park in Cape Coral for the Burrowing Owl Festival. Both of these events are solar observing and displays/handouts. We can use help with these events. You don’t need to bring a scope or even be familiar with solar observing. There is a lot of public interaction and we need people for that. As a followup to the BOF, we will have a public star
    [Show full text]
  • Organic Matter in Cometary Environments
    life Review Organic Matter in Cometary Environments Adam J. McKay 1,2,* and Nathan X. Roth 3,4 1 Department of Physics, American University, Washington, DC 20016, USA 2 Planetary Systems Laboratory Code 693, Solar System Exploration Division, NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA 3 Astrochemistry Laboratory Code 691, Solar System Exploration Division, NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA; [email protected] 4 Universities Space Research Association, Columbia, MD 21046, USA * Correspondence: [email protected] Abstract: Comets contain primitive material leftover from the formation of the Solar System, making studies of their composition important for understanding the formation of volatile material in the early Solar System. This includes organic molecules, which, for the purpose of this review, we define as compounds with C–H and/or C–C bonds. In this review, we discuss the history and recent breakthroughs of the study of organic matter in comets, from simple organic molecules and photodissociation fragments to large macromolecular structures. We summarize results both from Earth-based studies as well as spacecraft missions to comets, highlighted by the Rosetta mission, which orbited comet 67P/Churyumov–Gerasimenko for two years, providing unprecedented insights into the nature of comets. We conclude with future prospects for the study of organic matter in comets. Keywords: comet; organics; volatiles; astrobiology 1. Introduction Comets are primitive leftovers from the formation of the Solar System. As such, their composition provides clues to physics and chemistry operating during the protoplane- Citation: McKay, A.J.; Roth, N.X. tary disk phase (Figure1), as well as the preceding phases of star formation (e.g., [ 1,2]).
    [Show full text]
  • Photometry and Polarimetry of the Nucleus of Comet 2P/Encke
    A&A 489, 1337–1343 (2008) Astronomy DOI: 10.1051/0004-6361:200809922 & c ESO 2008 Astrophysics Photometry and polarimetry of the nucleus of comet 2P/Encke H. Boehnhardt1,G.P.Tozzi2, S. Bagnulo3, K. Muinonen4, A. Nathues1, and L. Kolokolova5 1 Max-Planck-Institute for Solar System Research, Max-Planck-Str. 2, 37191 Katlenburg-Lindau, Germany e-mail: [email protected] 2 INAF Arcetri Observatory, Florence, Italy 3 Armagh Observatory, Armagh, Northern Ireland, UK 4 University Observatory, Helsinki, Finland 5 University of Maryland, College Park, Maryland, USA Received 7 April 2008 / Accepted 27 June 2008 ABSTRACT Context. Comet 2P/Encke, a short-period comet, is a favorable target for studies of light scattering by bare cometary nuclei. These studies enable assessment of the nucleus size, the material albedo, and the light-scattering properties of the cometary surface. Observations of 2P/Encke were completed between October to December 2006 when the comet approached the Sun between 2.7 and 2.1 AU. Aims. We characterize the activity of the cometary coma and the physical properties of the nucleus of 2P/Encke such as its size, albedo, colors, spectral slope, surface roughness, porosity, and single-particle properties. Methods. Broadband imaging photometry and broadband and narrowband linear polarimetry is measured for the nucleus of 2P/Encke over the phase-angle range 4−28 deg. Results. An analysis of the point spread function of the comet in polarimetric images reveal only weak coma activity in 2P/Encke, corresponding to dust production of the order of 0.05 kg/s. Over the measured phase-angle range the nucleus displays a color in- dependent photometric phase function of almost linear slope (β = 0.050 ± 0.004 mag/deg).
    [Show full text]
  • Secular Variation of Activity in and 9P/Tempel Comets 2P/Encke 1
    NASA-CR-201783 Secular Variation of Activity in Comets 2P/Encke and 9P/Tempel 1 Michael Haken and Michael F. A'Hearn Department of Astronomy, University of Maryland, College Park, Maryland 20742 Paul D. Feldman Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218 Scott A. Budzien E.O. Hulburt Center for Space Research, Naval Research Laboratory, Washington, D.C. 20375 Abstract We compare production rates of H20 derived from International Ultraviolet Explorer (IUE) spectra from multiple apparitions of 2 comets, 2P/Encke and 9P/Tempel l, whose orbits are in near-resonance with that of the Earth. Since model-induced errors are primarily a function of observing geometry, the close geometrical matches afforded by the resonance condition results in the cancellation of such errors when taking ratios of production rates. Giving careful attention to the variation of model parameters with solar activity, we find marginal evidence of change in 2P/Encke: a 1-a pre-perihelion decrease averaging 4%/revolution over 4 apparitions from 1980-1994, and a 1-a post-perihelion increase of 16%/revolution for 2 successive apparitions in 1984 and 1987. We find for 9P/Tempel 1, however, a 7-a decrease of 29_0/revolution over 3 apparitions from 1983- 1994, even after correcting for a tracking problem which made the fluxes systematically low. We speculate on a possible association of the character of long-term brightness variations with physical properties of the nucleus, and discuss implications for future research. 1 Introduction Secular variations in comets may be important indicators of physical properties or pro- cesses which are inaccessible to direct scrutiny, but they may themselves be rather difficult to detect.
    [Show full text]
  • Ice & Stone 2020
    Ice & Stone 2020 WEEK 27: JUNE 28-JULY 4 Presented by The Earthrise Institute # 27 Authored by Alan Hale This week in history JUNE 28 29 30 1 2 3 4 JUNE 28, 1911: A meteorite falls to the ground near the village of El Nakhla El Bahariya, Egypt. The Nakhla meteorite was one of the first-known meteorites determined to have come from Mars. A fragment of the Nakhla meteorite supposedly struck and killed a dog, although there has been no independent confirmation of this. “Martian meteorites” are discussed in a future “Special Topics” presentation. JUNE 28, 2011: A team of astronomers led by Mark Showalter discovers Pluto’s fourth known moon, Kerberos, in images taken with the Hubble Space Telescope. Pluto and its system of moons are discussed in a future “Special Topics” presentation. JUNE 28 29 30 1 2 3 4 JUNE 30, 1861: Comet Tebbutt 1861 II passes 0.133 AU from Earth, in the process becoming one of the brightest and most spectacular comets of the 19th Century. It is this week’s “Comet of the Week.” JUNE 30, 1908: An object, perhaps 50 to 80 meters in diameter, enters Earth’s atmosphere over northeastern Asia and explodes several km above the ground near the Stony Tunguska River in central Siberia, creating widespread devastation for hundreds of square km around. The “Tunguska Event,” as this has come to be called, is the largest impact event on Earth in recent history, and it, together with some smaller more recent events, is the subject of this week’s “Special Topics” presentation.
    [Show full text]