DOCSLIB.ORG

Asteroid Models for PACS and SPIRE Calibration

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Asteroid Models for PACS and SPIRE Calibration Asteroid models for PACS and SPIRE calibration Thomas M¨uller,MPE, Jan. 19, 2012 1. Asteroid calibration observations 2. Sample for flux calibration PACS & SPIRE results 3. Asteroids as prime calibrators 4. Cross-calibration aspects 5. Next steps and future plans 1 Why asteroid calibration observations? • absolute flux calibration better than 5% in the entire flux regime • characterisation of point-spread-function (PSF) • important sources for filter leak tests and colour-corrections • spatial calibration aspects via asteroid-planet-star encounters • sources for detector linearity tests (connecting stars & planets) • establishment of relative spectral response function (RSRF) • technical telescope aspects: tracking & pointing system • cross-calibration between instruments, observing modes, with other missions, over time, across different wavelength & flux regimes, ... • anything where bright, point-like sources of known fluxes and with featureless SEDs are needed 2 Overview PACS/SPIRE asteroid calibration PacsCal PacsRangeSpec PV 16.2 h PacsCal Phot PSF FieldDistort 3.4 h PacsCal Spec Chopped Raster 1.2 h PacsCal WaveCalChop 1.7 h PacsPhoto 33.7 h PacsRangeSpec 41.4 h SpirePacsParallel 2.5 h SpirePhoto 67.9 h SpireSpectrometer 46.7 h • Until Dec. 2011, Herschel has spent about 215 h on asteroids for calibration purposes (PACS & SPIRE) • In total, more than 900 individual calibration observations (OBSIDs) • Thermophysical model calculations have been provided on request, typ- ically per OBSID, SEDs with pre-defined resolution or monochromatic flux densities at given reference wavelengths • All models have the same version, i.e., based on a fixed set of model parameters per object (for consistency reasons) 3 Asteroid sample for absolute flux calibration 4 Asteroid sample for absolute flux calibration • About 25 main-belt asteroids have been observed for flux calibration purposes by PACS and SPIRE • The original list of 55 asteroids has been down-selected to 12 high-quality objects (May 2011): 1 Ceres, 2 Pallas, 3 Juno, 4 Vesta, 6 Hebe, 8 Flora, 10 Hygiea, 20 Massalia, 21 Lutetia, 52 Europa, 88 Thisbe, 704 Interamnia • based on Herschel (PACS/SPIRE) observations and including checks against other data from ground (mid-IR/submm/mm) and space (IRAS, ISO, MSX, Spitzer, Akari) • For these 12 targets the derived Herschel (PACS/SPIRE) monochromatic flux densities are typically within 5% of the model predictions (full thermo- physical models, including shape models, rotation properties, thermal surface properties, true size and albedo values, ....). • Some are still outside the 5% corridor, but have the potential to reach that zone via external information (new shape and/or size information) 5 SPIRE: asteroid flux calibration (1) Timeline of SPIRE asteroid observations 6 SPIRE: asteroid flux calibration (2) 7 SPIRE: asteroid flux calibration (3) 8 PACS: asteroid flux calibration (1) • On average, the mini scan-map observations of the 18 asteroids agree within 2% in all 3 bands with the corresponding model predictions (giving each asteroid the same weight; after colour-correction) • blue band, 53 independent high-quality observations: stdev = 0.036 • green band, 53 independent high-quality observations: stdev = 0.036 • red band, 119 independent high-quality observations: stdev = 0.042 • Numbers do change slightly (a few percent), depending on settings for specific reduction steps: deglitching, masking/HPFW, aperture size, ... 9 10 11 12 Individual asteroids as prime calibrators? 21 Lutetia (Rosetta) 4 Vesta (DAWN) 13 21 Lutetia Rosetta flyby target (shape model by Carry et al. 2010) 14 15 16 21 Lutetia O'Rourke, M¨ulleret al. 2012 17 18 SPIRE FTS and photometer data on Pallas and Vesta 19 Individual asteroids as prime calibrators (2) • Best candidates: 1 Ceres, 2 Pallas, 4 Vesta, 21 Lutetia • Ceres and Vesta have more than 10 independent observations with each instrument, Pallas just below 10, Lutetia only a few • Model predictions are based on pre-Herschel model parameters • Derived fluxes depend slightly on data reduction details • Completely different calibration schemes for PACS & SPIRE Ast. 70 100 160 250 350 500 µm 1 1.05±0.02 1.03±0.02 1.07±0.02 1.00±0.03 1.01±0.02 1.00±0.03 2 1.06±0.02 1.05±0.03 1.10±0.03 1.09±0.03 1.10±0.03 1.10±0.03 4 1.02±0.03 1.08±0.03 1.14±0.04 1.07±0.02 1.11±0.02 1.09±0.02 21 1.07±0.07 1.07±0.05 1.11±0.07 1.00±0.06 1.01±0.04 0.94±0.08 Excellent cross-calibration results! 20 Individual asteroids as prime calibrators (3) • Several asteroids are on a path to become truly prime flux calibrators: Absolute flux predictions <5% in FIR/submm/mm, at any given time • Availability of highly accurate shape models, spin-axis characterisation, surface properties for 1 Ceres, (2 Pallas), 4 Vesta, 21 Lutetia • Large database of thermal observations available, for fine-tuning relevant pa- rameters, like surface roughness and thermal inertia • The PACS and SPIRE fluxes will play a key role when converting them to prime calibrators (in Herschel post-mission phase) • 21 Lutetia: the Rosetta shape model is available and publications are submit- ted (O'Rourke et al.; Carry et al. 2012), but only ∼60% of the surface was seen, the rest is re-constructed via other techniques • 4 Vesta: DAWN Mission is still at Vesta (until July 2012), shape model will be available soon • 1 Ceres & 2 Pallas: new shape models by Carry et al. 2009/2010 • 1 Ceres: DAWN Mission will arrive at Ceres in Feb. 2015 21 Asteroid cross-calibration aspects • SOFIA/APEX/ALMA: use the same list of 12 asteroids based on the same models • All 3 projects have meanwhile observed a few of the asteroids • coordinated activities with Planck on many asteroids (and planets), but no feeback on Planck fluxes so far • current main cross-calibration tasks - PACS photometer vs. spectrometer - SPIRE photometer vs. spectrometer - PACS vs. SPIRE - Connecting a stellar based calibration scheme (PACS, gb-MIR) to a planet based calibration scheme (SPIRE, gb-submm/mm) 22 Outlook & Next Steps • continuation of asteroid model calculations on request • collaborations with Benoit Carry (ESAC) and Josef Durech (Prague Univer- sity) to establish better shape/spin-vector models for key asteroids • collection and identification of key thermal data per object • ISSI-project with a focus on thermal surface effects has started Oct. 2011 (funded for 2 years) • aspect for the near future and post-operations phase: - collect all Herschel observations of calibrators (planets, stars, asteroids) - combine with auxiliary data from ground (lightcurves, occultations) - combine with space data (Planck, Rosetta, Dawn, ...) - tune calibrators for future projects: SOFIA, ALMA, JWST, SPICA, .... - updated calibrator models, including new primary standards! ) An important legacy of Herschel! 23.
Load more

Recommended publications
  • ESO's VLT Sphere and DAMIT
    ESO’s VLT Sphere and DAMIT ESO’s VLT SPHERE (using adaptive optics) and Joseph Durech (DAMIT) have a program to observe asteroids and collect light curve data to develop rotating 3D models with respect to time. Up till now, due to the limitations of modelling software, only convex profiles were produced. The aim is to reconstruct reliable nonconvex models of about 40 asteroids. Below is a list of targets that will be observed by SPHERE, for which detailed nonconvex shapes will be constructed. Special request by Joseph Durech: “If some of these asteroids have in next let's say two years some favourable occultations, it would be nice to combine the occultation chords with AO and light curves to improve the models.” 2 Pallas, 7 Iris, 8 Flora, 10 Hygiea, 11 Parthenope, 13 Egeria, 15 Eunomia, 16 Psyche, 18 Melpomene, 19 Fortuna, 20 Massalia, 22 Kalliope, 24 Themis, 29 Amphitrite, 31 Euphrosyne, 40 Harmonia, 41 Daphne, 51 Nemausa, 52 Europa, 59 Elpis, 65 Cybele, 87 Sylvia, 88 Thisbe, 89 Julia, 96 Aegle, 105 Artemis, 128 Nemesis, 145 Adeona, 187 Lamberta, 211 Isolda, 324 Bamberga, 354 Eleonora, 451 Patientia, 476 Hedwig, 511 Davida, 532 Herculina, 596 Scheila, 704 Interamnia Occultation Event: Asteroid 10 Hygiea – Sun 26th Feb 16h37m UT The magnitude 11 asteroid 10 Hygiea is expected to occult the magnitude 12.5 star 2UCAC 21608371 on Sunday 26th Feb 16h37m UT (= Mon 3:37am). Magnitude drop of 0.24 will require video. DAMIT asteroid model of 10 Hygiea - Astronomy Institute of the Charles University: Josef Ďurech, Vojtěch Sidorin Hygiea is the fourth-largest asteroid (largest is Ceres ~ 945kms) in the Solar System by volume and mass, and it is located in the asteroid belt about 400 million kms away.
    [Show full text]
  • (704) Interamnia from Its Occultations and Lightcurves
    International Journal of Astronomy and Astrophysics, 2014, 4, 91-118 Published Online March 2014 in SciRes. http://www.scirp.org/journal/ijaa http://dx.doi.org/10.4236/ijaa.2014.41010 A 3-D Shape Model of (704) Interamnia from Its Occultations and Lightcurves Isao Satō1*, Marc Buie2, Paul D. Maley3, Hiromi Hamanowa4, Akira Tsuchikawa5, David W. Dunham6 1Astronomical Society of Japan, Yamagata, Japan 2Southwest Research Institute, Boulder, USA 3International Occultation Timing Association, Houston, USA 4Hamanowa Astronomical Observatory, Fukushima, Japan 5Yanagida Astronomical Observatory, Ishikawa, Japan 6International Occultation Timing Association, Greenbelt, USA Email: *[email protected], [email protected], [email protected], [email protected], [email protected], [email protected] Received 9 November 2013; revised 9 December 2013; accepted 17 December 2013 Copyright © 2014 by authors and Scientific Research Publishing Inc. This work is licensed under the Creative Commons Attribution International License (CC BY). http://creativecommons.org/licenses/by/4.0/ Abstract A 3-D shape model of the sixth largest of the main belt asteroids, (704) Interamnia, is presented. The model is reproduced from its two stellar occultation observations and six lightcurves between 1969 and 2011. The first stellar occultation was the occultation of TYC 234500183 on 1996 De- cember 17 observed from 13 sites in the USA. An elliptical cross section of (344.6 ± 9.6 km) × (306.2 ± 9.1 km), for position angle P = 73.4 ± 12.5˚ was fitted. The lightcurve around the occulta- tion shows that the peak-to-peak amplitude was 0.04 mag. and the occultation phase was just be- fore the minimum.
    [Show full text]
  • IRTF Spectra for 17 Asteroids from the C and X Complexes: a Discussion of Continuum Slopes and Their Relationships to C Chondrites and Phyllosilicates ⇑ Daniel R
    Icarus 212 (2011) 682–696 Contents lists available at ScienceDirect Icarus journal homepage: www.elsevier.com/locate/icarus IRTF spectra for 17 asteroids from the C and X complexes: A discussion of continuum slopes and their relationships to C chondrites and phyllosilicates ⇑ Daniel R. Ostrowski a, Claud H.S. Lacy a,b, Katherine M. Gietzen a, Derek W.G. Sears a,c, a Arkansas Center for Space and Planetary Sciences, University of Arkansas, Fayetteville, AR 72701, United States b Department of Physics, University of Arkansas, Fayetteville, AR 72701, United States c Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, AR 72701, United States article info abstract Article history: In order to gain further insight into their surface compositions and relationships with meteorites, we Received 23 April 2009 have obtained spectra for 17 C and X complex asteroids using NASA’s Infrared Telescope Facility and SpeX Revised 20 January 2011 infrared spectrometer. We augment these spectra with data in the visible region taken from the on-line Accepted 25 January 2011 databases. Only one of the 17 asteroids showed the three features usually associated with water, the UV Available online 1 February 2011 slope, a 0.7 lm feature and a 3 lm feature, while five show no evidence for water and 11 had one or two of these features. According to DeMeo et al. (2009), whose asteroid classification scheme we use here, 88% Keywords: of the variance in asteroid spectra is explained by continuum slope so that asteroids can also be charac- Asteroids, composition terized by the slopes of their continua.
    [Show full text]
  • (704) INTERAMNIA A. Kovačević
    VI Serbian-Belarusian Symp. on Phys. and Diagn. of Lab. & Astrophys. Plasma, Belgrade, Serbia, 22 - 25 August 2006 eds. M. Ćuk, M.S. Dimitrijević, J. Purić, N. Milovanović Publ. Astron. Obs. Belgrade No. 82 (2007), 241-243 Contributed paper ASTEROID CLOSE ENCOUNTERS WITH (704) INTERAMNIA A. Kovačević Department of Astronomy,Faculty of Mathematics,Belgrade [email protected] Abstract.Interamnia is the seventh largest known asteroid with an estimated diameter larger than 300 km and was discovered (surprisingly late for such a large object) on October 2, 1910 by Vincenzo Cerulli. The technique of asteroid mass determination from perturbation during close approach requires as many as possibledifferent close approaches in order to derive reliable mass of a perturber. Here is presented list of newlyfound close encounters with the asteroid (704) Interamnia which could be used for its mass determination.. 1. INTRODUCTION The number of papers devoted to mass determinations of large asteroids is raising in recent years.There are several facts that influenced such a determination- the discovery of satellites of asteroids (e.g. [1, 2]), measurements by space probes that visited asteroids [3] and growing number of astrometrical measurements with increased precision [4]. As is well known, the method of minor planet mass determination that considers gravitational perturbations produced by asteroid on other bodies during mutual close encounter was developed first. The aim of this paper is to introduce close encounters suitable for mass determination of seventh largest asteroid (704) Interamnia by astrometric methods. 2. SELECTION PROCESS The initial osculating orbital elements for epoch JD 2451600.5, were taken from E.
    [Show full text]
  • Infrared Spectroscopy of Large, Low-Albedo Asteroids: Are Ceres and Themis Archetypes Or Outliers?
    Infrared Spectroscopy of Large, Low-Albedo Asteroids: Are Ceres and Themis Archetypes or Outliers? Andrew S. Rivkin1, Ellen S. Howell2, Joshua P. Emery3 1. Johns Hopkins University Applied Physics Laboratory 2. University of Arizona 3. University of Tennessee Corresponding author: Andrew Rivkin ([email protected]) Key points: • The largest low-albedo asteroids appear to be unrepresented in the meteorite collection • Reflectance spectra in the 3-µm spectral region, and presumably compositions, similar to Ceres and Themis appear to be common in low-albedo asteroids > 200 km diameter • The asteroid 324 Bamberga appears to have hemispherical-scale variation in its reflectance spectrum, and in places has a spectrum reminiscent of Comet 67P. Submitted to Journal of Geophysical Research 17 September 2018 Revised 27 February 2019 Accepted 12 April 2019 1 Abstract: Low-albedo, hydrated objects dominate the list of the largest asteroids. These objects have varied spectral shapes in the 3-µm region, where diagnostic absorptions due to volatile species are found. Dawn’s visit to Ceres has extended the view shaped by ground-based observing, and shown that world to be a complex one, potentially still experiencing geological activity. We present 33 observations from 2.2-4.0 µm of eight large (D > 200 km) asteroids from the C spectral complex, with spectra inconsistent with the hydrated minerals we see in meteorites. We characterize their absorption band characteristics via polynomial and Gaussian fits to test their spectral similarity to Ceres, the asteroid 24 Themis (thought to be covered in ice frost), and the asteroid 51 Nemausa (spectrally similar to the CM meteorites).
    [Show full text]
  • (704) Interamnia: a Transitional Object Between a Dwarf Planet and a Typical Irregular-Shaped Minor Body G
    (704) Interamnia: a transitional object between a dwarf planet and a typical irregular-shaped minor body G. Dudziński, E. Podlewska-Gaca, P. Bartczak, S Benseguane, M. Ferrais, L. Jorda, J. Hanuš, P. Vernazza, N. Rambaux, B. Carry, et al. To cite this version: G. Dudziński, E. Podlewska-Gaca, P. Bartczak, S Benseguane, M. Ferrais, et al.. (704) Interamnia: a transitional object between a dwarf planet and a typical irregular-shaped minor body. Astronomy and Astrophysics - A&A, EDP Sciences, 2020, 633 (2), pp.A65. 10.1051/0004-6361/201936639. hal- 02996661 HAL Id: hal-02996661 https://hal.archives-ouvertes.fr/hal-02996661 Submitted on 15 Apr 2021 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. A&A 633, A65 (2020) Astronomy https://doi.org/10.1051/0004-6361/201936639 & © ESO 2020 Astrophysics (704) Interamnia: a transitional object between a dwarf planet and a typical irregular-shaped minor body?,?? J. Hanuš1, P. Vernazza2, M. Viikinkoski3, M. Ferrais4,2, N. Rambaux5, E. Podlewska-Gaca6, A. Drouard2, L. Jorda2, E. Jehin4, B. Carry7, M. Marsset8, F. Marchis9, B. Warner10, R. Behrend11, V. Asenjo12, N. Berger13, M. Bronikowska14, T.
    [Show full text]
  • I(NASA-CR-154510') ASTEROID SURFACE
    REFLECTANCE S PECV A By Michael J. Gaffey Thomas B. McCord (NASA-CR-154510') ASTEROID SURFACE N8-'10992 iMATERIALS: MINERALOGICAL.CHARACTERIZATIONS FROM REFLECTANCE SPECTRA (Hawaii Univ.), 147 p HC -A07/MF A01 CSCL 03B Unclas G , ­ to University of Hawaii at Manoa Institute for Astronomy 2680 Woodlawn Drive * Honolulu, Hawaii 96822 Telex: 723-8459 * UHAST HR November 18, 1977 NASA Scientific and Technical Information Facility P.O. Box 8757 Baltimore/Washington Int. Airport Maryland 21240 Gentlemen: RE: Spectroscopy of Asteroids, NSG 7310 Enclosed are two copies of an article entitled "Asteroid Surface Materials: Mineralogical Characterist±cs from Reflectance Spectra," by Dr. Michael J. Gaffey and Dr. Thomas B. McCord, which we have recently submitted for publication to Space Science Reviews. We submit these copies in accordance with the requirements of our NASA grants. Sincerely yours, Thomas B. McCord Principal Investigator TBM:zc Enclosures AN EQUAL OPPORTUNITY EMPLOYER ASTEROID SURFACE MATERIALS: MINERALOGICAL CHARACTERIZATIONS FROM REFLECTANCE SPECTRA By Michael J. Gaffey Thomas B. McCord Institute for Astronomy University of Hawaii at Manoa 2680 Woodlawn Drive Honolulu, Hawaii 96822 Submitted to Space Science Reviews Publication #151 of the Remote Sensing Laboratory Abstract The interpretation of diagnostic parameters in the spectral reflectance data for asteroids provides a means of characterizing the mineralogy and petrology of asteroid surface materials. An interpretive technique based on a quantitative understanding of the functional relationship between the optical properties of a mineral assemblage and its mineralogy, petrology and chemistry can provide a considerably more sophisticated characterization of a surface material than any matching or classification technique. for those objects bright enough to allow spectral reflectance measurements.
    [Show full text]
  • The Gaia Astrophysical Parameters Inference System (Apsis). Pre
    Astronomy & Astrophysics manuscript no. apsis2013 c ESO 2013 10 September 2013 The Gaia astrophysical parameters inference system (Apsis) Pre-launch description C.A.L. Bailer-Jones1∗, R. Andrae1, B. Arcay2, T. Astraatmadja1, I. Bellas-Velidis3, A. Berihuete4, A. Bijaoui5, C. Carrión6, C. Dafonte2, Y. Damerdji7; 8, A. Dapergolas3, P. de Laverny5, L. Delchambre7, P. Drazinos9, R. Drimmel10, Y. Frémat11, D. Fustes2, M. García-Torres12, C. Guédé13; 14, U. Heiter15, A.-M. Janotto16, A. Karampelas9, D.-W. Kim1, J. Knude17, I. Kolka18, E. Kontizas3, M. Kontizas9, A.J. Korn15, A.C. Lanzafame19; 20, Y. Lebreton13; 14, H. Lindstrøm17; 21, C. Liu1, E. Livanou9, A. Lobel11, M. Manteiga2, C. Martayan22, Ch. Ordenovic5, B. Pichon5, A. Recio-Blanco5, B. Rocca-Volmerange23; 24, L.M. Sarro6, K. Smith1, R. Sordo25, C. Soubiran26, J. Surdej7, F. Thévenin5, P. Tsalmantza1, A. Vallenari25, and J. Zorec23 (Affiliations can be found after the references) submitted 23 July 2013; revised 8 September 2013; accepted 9 September 2013 ABSTRACT The Gaia satellite will survey the entire celestial sphere down to 20th magnitude, obtaining astrometry, photometry, and low resolution spectrophotometry on one billion astronomical sources, plus radial velocities for over one hundred million stars. Its main objective is to take a census of the stellar content of our Galaxy, with the goal of revealing its formation and evolution. Gaia’s unique feature is the measurement of parallaxes and proper motions with hitherto unparalleled accuracy for many objects. As a survey, the physical properties of most of these objects are unknown. Here we describe the data analysis system put together by the Gaia consortium to classify these objects and to infer their astrophysical properties using the satellite’s data.
    [Show full text]
  • New and Updated Convex Shape Models of Asteroids Based on Optical Data from a Large Collaboration Network
    A&A 586, A108 (2016) Astronomy DOI: 10.1051/0004-6361/201527441 & c ESO 2016 Astrophysics New and updated convex shape models of asteroids based on optical data from a large collaboration network J. Hanuš1,2,J.Durechˇ 3, D. A. Oszkiewicz4,R.Behrend5,B.Carry2,M.Delbo2,O.Adam6, V. Afonina7, R. Anquetin8,45, P. Antonini9, L. Arnold6,M.Audejean10,P.Aurard6, M. Bachschmidt6, B. Baduel6,E.Barbotin11, P. Barroy8,45, P. Baudouin12,L.Berard6,N.Berger13, L. Bernasconi14, J-G. Bosch15,S.Bouley8,45, I. Bozhinova16, J. Brinsfield17,L.Brunetto18,G.Canaud8,45,J.Caron19,20, F. Carrier21, G. Casalnuovo22,S.Casulli23,M.Cerda24, L. Chalamet86, S. Charbonnel25, B. Chinaglia22,A.Cikota26,F.Colas8,45, J.-F. Coliac27, A. Collet6,J.Coloma28,29, M. Conjat2,E.Conseil30,R.Costa28,31,R.Crippa32, M. Cristofanelli33, Y. Damerdji87, A. Debackère86, A. Decock34, Q. Déhais36, T. Déléage35,S.Delmelle34, C. Demeautis37,M.Dró˙zd˙z38, G. Dubos8,45, T. Dulcamara6, M. Dumont34, R. Durkee39, R. Dymock40, A. Escalante del Valle85, N. Esseiva41, R. Esseiva41, M. Esteban24,42, T. Fauchez34, M. Fauerbach43,M.Fauvaud44,45,S.Fauvaud8,44,45,E.Forné28,46,†, C. Fournel86,D.Fradet8,45, J. Garlitz47, O. Gerteis6, C. Gillier48, M. Gillon34, R. Giraud34, J.-P. Godard8,45,R.Goncalves49, Hiroko Hamanowa50, Hiromi Hamanowa50,K.Hay16, S. Hellmich51,S.Heterier52,53, D. Higgins54,R.Hirsch4, G. Hodosan16,M.Hren26, A. Hygate16, N. Innocent6, H. Jacquinot55,S.Jawahar56, E. Jehin34, L. Jerosimic26,A.Klotz6,57,58,W.Koff59, P. Korlevic26, E. Kosturkiewicz4,38,88,P.Krafft6, Y. Krugly60, F. Kugel19,O.Labrevoir6, J.
    [Show full text]
  • Obliquity, Precession Rate, and Nutation Coefficients for a Set of 100 Asteroids
    A&A 556, A8 (2013) Astronomy DOI: 10.1051/0004-6361/201321205 & c ESO 2013 Astrophysics Obliquity, precession rate, and nutation coefficients for a set of 100 asteroids C. Lhotka1, J. Souchay2, and A. Shahsavari2 1 Department of Mathematics, University of Rome Tor Vergata, 00133 Rome, Italy 2 Observatoire de Paris, SYRTE/UMR-8630 CNRS, 75014 Paris, France e-mail: [email protected] Received 31 January 2013 / Accepted 18 April 2013 ABSTRACT Context. Thanks to various space missions and the progress of ground-based observational techniques, the knowledge of asteroids has considerably increased in the recent years. Aims. Due to this increasing database that accompanies this evolution, we compute for a set of 100 asteroids their rotational parame- ters: the moments of inertia along the principal axes of the object, the obliquity of the axis of rotation with respect to the orbital plane, the precession rates, and the nutation coefficients. Methods. We select 100 asteroids for which the parameters for the study are well-known from observations or space missions. For each asteroid, we determine the moments of inertia, assuming an ellipsoidal shape. We calculate their obliquity from their orbit (instead of the ecliptic) and the orientation of the spin-pole. Finally, we calculate the precession rates and the largest nutation compo- nents. The number of asteroids concerned leads to some statistical studies of the output. Results. We provide a table of rotational parameters for our set of asteroids. The table includes the obliquity, their axes ratio, their dynamical ellipticity Hd, and the scaling factor K. We compute the precession rate ψ˙ and the leading nutation coefficients Δψ and Δε.
    [Show full text]
  • Astrometric Masses of 21 Asteroids, and an Integrated Asteroid Ephemeris
    View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Springer - Publisher Connector Celestial Mech Dyn Astr (2008) 100:27–42 DOI 10.1007/s10569-007-9103-8 ORIGINAL ARTICLE Astrometric masses of 21 asteroids, and an integrated asteroid ephemeris James Baer · Steven R. Chesley Received: 28 June 2007 / Revised: 14 October 2007 / Accepted: 25 October 2007 / Published online: 18 December 2007 © Springer Science+Business Media B.V. 2007 Abstract We apply the technique of astrometric mass determination to measure the masses − of 21 main-belt asteroids; the masses of 9 Metis (1.03 ± 0.24 × 10 11 M), 17 Thetis − − (6.17 ± 0.64 × 10 13 M), 19 Fortuna (5.41 ± 0.76 × 10 12 M), and 189 Phthia (1.87 ± − 0.64×10 14 M) appear to be new. The resulting bulk porosities of 11 Parthenope (12±4%) and 16 Psyche (46±16%) are smaller than previously-reported values. Empirical expressions modeling bulk density as a function of mean radius are presented for the C and S taxonomic classes. To accurately model the forces on these asteroids during the mass determination process, we created an integrated ephemeris of the 300 large asteroids used in preparing the DE-405 planetary ephemeris; this new BC-405 integrated asteroid ephemeris also appears useful in other high-accuracy applications. Keywords N-body · Asteroid · Ephemerides · Asteroid masses · Astrometric masses · Asteroid porosity 1 Introduction The technique of astrometric mass determination, in which the deflection of a small body’s trajectory allows us to deduce the mass of a larger perturbing body, may be entering a partic- ularly fruitful period, as near-Earth asteroid (NEA) surveys coincidentally produce a flood of high-precision main-belt asteroid observations.
    [Show full text]
  • Observer's Handbook 1981
    OBSERVER’S HANDBOOK 1 9 8 1 EDITOR: JOHN R. PERCY ROYAL ASTRONOMICAL SOCIETY OF CANADA CONTRIBUTORS AND ADVISORS A l a n H. B a t t e n , Dominion Astrophysical Observatory, Victoria, B.C., Canada V8X 3X3 (The Nearest Stars). Terence Dickinson, Editor, Star and Sky, 44 Church Lane, Westport, Conn. 06880 (The Planets). Alan Dyer, Queen Elizabeth Planetarium, 10004-104 Ave., Edmonton, Alta. T5J 0K 1 (Messier Catalogue, Deep-Sky Objects). M arie Fidler, Royal Astronomical Society of Canada, 124 Merton St., Toronto, Ont., Canada M4S 2Z2 (Observatories and Planetariums). V ictor Gaizauskas, Herzberg Institute of Astrophysics, National Research Council, Ottawa, Ont., Canada K1A 0R6 (Sunspots). J o h n A. G a l t , Dominion Radio Astrophysical Observatory, Penticton, B.C., Canada V2A 6K3 (Radio Sources). Ian H alliday, Herzberg Institute of Astrophysics, National Research Council, Ottawa, Ont., Canada K1A 0R6 (Miscellaneous Astronomical Data). H e l e n S. H o g g , David Dunlap Observatory, University of Toronto, Richmond Hill, Ont., Canada L4C 4Y6 (Foreword). D o n a l d A. M a c R a e , David Dunlap Observatory, University of Toronto, Richmond Hill, Ont., Canada L4C 4Y6 (The Brightest Stars). B r i a n G. M a r s d e n , Smithsonian Astrophysical Observatory, Cambridge, Mass., U.S.A. 02138 (Comets, Minor Planets). J a n e t A. M a t t e i , American Association of Variable Star Observers, 187 Concord Ave., Cambridge, Mass. U.S.A. 02138 (Variable Stars). P e t e r M. M i l l m a n , Herzberg Institute of Astrophysics, National Research Council, Ottawa, Ont., Canada K1A 0R6 (Meteors, Fireballs and Meteorites).
    [Show full text]