Observations - October, 2011
Abstracts
ALFALFA: The Arecibo Legacy Fast ALFA Survey (A2010)
PI òÀÓ Dr. Riccardo Giovanelli, Cornell University
Co-PI òÀÓ Dr. Martha Haynes
Proposal Date: September 29, 2004
Abstract: We propose to initiate the Arecibo Legacy Fast ALFA (ALFALFA) Survey, a key element of the E-ALFA Consortium science program. Conducted in a 2-pass fixed-azimuth drift mode sampling 100 MHz with 5 km/s resolution, ALFALFA will survey 7000 square degrees away from the galactic plane, including both the rich central regions of the Local Supercluster and the low density anti-Virgo region. It is specifically designed to explore the very low mass end of the HI mass function in the local universe, the nature of dwarf galaxies and high velocity clouds, the extent and origin of HI disks, and the structure and dynamics of the Local Supercluster. As a wide area legacy survey, ALFALFA will enable a broad range of correlative studies with like datasets such as SDSS, 2MASS and GALEX to quantify environmental variations in the Local and nearby superclusters such as Pisces-Perseus and A1367-Coma. Eight times more sensitive than HIPASS with 4 times the angular resolution, ALFALFA will also provide the first wide area blind survey for HI tidal remnants, low z HI absorbers and OH megamasers in the range 0.16 <z <0.25. Its dataset will also be used in the statistical characterization of continuum transients, and both G-ALFA and P-ALFA programs will be conducted commensally, when multiple backends are available. Top
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The G-ALFA Continuum Transit Survey (A2130)
PI òÀÓ Dr. Andrew R. Taylor, University of Calgary
Co-PI òÀÓ Dr. Christopher J. Salter
Proposal Date: June 1st, 2005
Abstract: As part of the GALFA consortium we propose to use Arecibo and ALFA to carry out a sensitive, high resolution, spectro-polarimetric survey of the Arecibo sky òÀÓ the GALFA Continuum Transit Survey, GALFACTS. GALFACTS will be a major observational advance in imaging of the polarized radiation from the Milky Way and other galaxies, and promises a transformational advance in our understanding of the magnetic field of the Milky Way, the properties of the magneto-ionic medium, and the role of magnetic fields in galactic processes. We will also explore the polarization properties of a vast number of extragalactic radio sources down to sub-mJy levels. GALFACTS will be a scientific pathfinder to the Square Kilometer Array in the area of cosmic magnetism, and will not be surpassed until the SKA turns on as survey instrument late in the next decade. Top
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The Alfa Ultra-Deep Survey: Deep HI Observations at 0<z<0.16 (A2133)
PI òÀÓ Dr. Wolfram Freudling, Space Telescope - European Coordinating Facility
Proposal Date: June 8, 2008
Abstract: The improved spatial and spectral survey capabilities available with ALFA opened a new era of high sensitivity observations for the Arecibo telescope. In a precursor experiment, we have demonstrated that it is possible to achieve noise of less than 50micro-Jy with integration times of about 40 hours per pointing, which translates into a HI mass sensitivity of a few 10E8 Msun at a redshift of about 0.16. We propose to use the new 200 MHz spectrometer available in late 2005 to carry out a blind HI survey with unprecedented sensitivity of 50micro-Jy for the redshift range of 0<z<0.16 over a total area of 0.36 square degrees. The "ALFA Ultra Deep Survey" (AUDS) survey is more than an order of magnitude more sensitive than other HI surveys currently being carried out at Arecibo. The main scientific goals of the survey are to investigate the evolution of HI gas in the universe and explore the low-density gas around the edges of galaxies. The survey will be the deepest "blind" HI survey ever conducted. It will provide for the first time a direct link between HI absorption line measurements at high and intermediate redshifts and 21-cm emission line measurements at low redshifts. The expected number of HI detections at z>0.1 will be larger than that of all previous targeted and blind surveys combined. Top
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GASS - The GALEX Arecibo SDSS Survey (A2335)
PI òÀÓ Dr. David Schiminovich, Columbia University
Co-PI òÀÓ Dr. Barbara Cantinella
Proposal Date: June 1st, 2007
Abstract: We propose the GALEX Arecibo SDSS Survey (GASS) a large targeted survey designed to measure the HI content of about 1000 galaxies at redshift 0.025<z<0.05 uniformly selected from the SDSS spectroscopic and GALEX imaging surveys to have stellar mass greater than 1e10 Msun. Our selected mass range straddles the recently identified òÀÜtransition massòÀÝ (3e10 Msun) above which galaxies show a marked decrease in their present to past-averaged star formation rates. GASS will produce the first statistically significant sample of massive òÀÜtransitionòÀÝ galaxies with homogeneously measured stellar masses, star formation rates and gas properties. By observing these galaxies down to a low gas mass fraction limit (1.5%), GASS will provide new insight into the physical mechanisms that shape the stellar mass function, regulate gas accretion and quench further galaxy growth by conversion of gas into stars. GASS will be of considerable legacy value not only in isolation but also by complementing on-going HI-selected surveys. Top
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Discovering Milky Way HII Regions (A2500)
PI òÀÓ Dr. Thomas M. Bania, Boston University Astronomy Department
Co-PI òÀÓ Dr. Dana Balser
Proposal Date: May 22nd, 2009
Abstract: We are finding a large population of previously unknown Galactic HII regions using the GBT at X-band to discover recombination line (RRL) emission from these nebulae. Here we seek to extend our discovery survey by using the superior sensitivity of Arecibo to find nebulae that are too weak and too small to be detected by the GBT. Since HII region RRLs are optically thin at X-band we can discover HII regions across the entire Galactic disk. We can get a complete census of all nebulae ionized by single O-type stars in the survey zone. We will determine the nebular kinematic distances, luminosities, metallicities (via the electron temperature, Te) and helium abundances (4He/H=Y). Both Te and Y provide important constraints on models for Galactic chemical evolution, GCE, and about 10% of these new nebulae will be located in the GCE-critical region beyond the Solar orbit. Top
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Are Infrared Bubbles Actually Rings?(A2583)
PI òÀÓ Dr. Edward B Churchwell , University of Winsconsin
Co-PI òÀÓ Dr. Christopher N. Beaumont
Proposal Date: June 1st, 2010
Abstract: It has recently been questioned whether the interstellar òÀÜIR bubblesòÀÝ, of which Churchwell et al. cataloged 600, are 3D shells or 2D rings seen approximately face-on. This has important implications for the structure of molecular clouds. We propose a test between these two hypotheses. The associated HII regions would evolve differently depending upon how they are confined, possessing bipolar structures with expanding lobes in the ring case, but smaller, spherical forms, with slower expansion, for a surrounding shell. We propose observing 16 òÀÜIR bubblesòÀÝ at C-band, simultaneously recording 8 Hn lines to search for the broad/double lines from the HII regions predicted by the ring hypothesis. Numerous other recombination and molecular lines will also be recorded, allowing investigation of both the ionized gas and the surrounding molecular shells. Combining the formaldehyde and Hn spectra can distinguish between near and far kinetic distances for the individual nebulae. Top
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Densitometry of star-forming dusty clumps throughout the Galaxy (A2584)
PI òÀÓ Dr. Adam Ginsburg, University of Colorado, Boulder
Co-PI òÀÓ Dr. Jeremy Darling
Proposal Date: June 1st, 2010
Abstract: We propose to obtain measurements of the dense mass fraction of young star-forming complexes in a variety of Galactic environments using beam-matched formaldehyde absorption line observations on the GBT at 2 cm and Arecibo at 6 cm. The pilot program GBT09C-049, combined with archival Arecibo data, demonstrated the possibility of efficiently measuring dense gas mass fractions in Galactic molecular clumps with the GBT and Arecibo. We propose to expand that initial sample of 22 ultracompact HII regions to 409 clumps in a wide range of evolutionary states, including inactive and star-forming infrared dark clouds, HII regions, and filamentary structures. We will use formaldehyde densitometry to measure the density and dense gas mass fraction in these 409 clumps. These measurements will be used to track the evolutionary path of molecular clumps intermediate between giant molecular clouds and protostellar cores, and the large sample size will allow us to estimate the relative lifetimes of each state. The GBT observations have already been approved, but completion of this project depends critically on the Arecibo data. Top
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Mapping the Cold Local Ribbon (A2587)
PI òÀÓ Dr. Joshua E. Peek, Columbia University
Proposal Date: June 1st, 2011
Abstract: We have mapped a very cold local cloud using Arecibo, and we wish to extend these observations. The extant map has generated a veritable explosion of research and excitement. New distance constraints have been derived for the cloud, using the high fidelity Arecibo map paired with stellar absorption lines. The new distance 11 pc <D <24 pc has allowed us to use the cloud to study the environment of the local ISM. Indeed we have used it to show that the standard Local Hot Bubble paradigm, in which the local cavity is filled with millon degree gas, is incorrect, and that a òÀÙhot-topòÀÙ framework may be more accurate. An expansion of our map will allow us to 1) get better distance constraints to the cloud 2) expand our study of the details of the CNM and 3) get a better X-rays shadowing constraint, which will put the last nail in the coffin of the local hot bubble theory. Top
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Are molecular clouds magnetically subcritical or supercritical overall? A survey of Zeeman observations of OH in absorption II. (A2600)
PI òÀÓ Dr. Kristen L Thompson, University of Kentucky
Co-PI òÀÓ Dr. Thomas Troland
Proposal Date: September 30, 2011
Abstract: Although much Zeeman work has been done to study the effect of magnetic fields on molecular cloud cores, very little is known about fields in the general envelopes of molecular clouds. Are molecular clouds as a whole magnetically subcritical or supercritical?Using Arecibo, Thompson and Troland have begun the first systematic observational survey to address this question using the Zeeman effect in OH absorption toward extra-galactic continuum sources that lie behind molecular clouds. In this first survey we have studied 7 lines-of-sight. However, the Zeeman effect can only reveal the line-of-sight magnetic field, which makes this study inherently statistical in nature. To obtain statistically meaningful results for this project, we require magnetic field information for more than 7 lines-of-sight. We have identified 26 additional extra-galactic sources. We will chose about 10 of these sources based upon a short survey of OH optical depths and conduct Zeeman observations, spending about 20 hours on each source. Top
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Surveying the Zone of Avoidance with ALFA: Outer Galaxy Region (A2611)
PI òÀÓ Dr. Patricia Henning, University of New Mexico
Co-PI òÀÓ Dr. Travis McIntyre
Proposal Date: December 10th, 2010
Abstract: We propose to survey the Zone of Avoidance (ZOA) deeply at 21-cm using the ALFA system, mapping hidden galaxies and large-scale structures at low Galactic latitudes. Mapping galaxies in the ZOA is one of four large blind surveys endorsed by the Extragalactic ALFA consortium, and is the only low-Galactic latitude project so endorsed. Our project A2152, to conduct deep observations commensally with PALFA, received an "A" grade, and was to observe both the inner and outer Galaxy regions. We are proceeding commensally with PALFA (P2130) in the inner Galaxy region, and propose here that ZOA become primary project in the outer Galaxy region. We refer to our A2152 proposal for full scientific justification. Top
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OH Observations of four comets June 2011 - January 2012 (A2616)
PI òÀÓ Dr. Ellen S. Howell, Arecibo Observatory
Co-PI òÀÓ Dr. Amy J. Lovell
Proposal Date: February 6, 2011
Abstract: We propose to continue our measurements of OH lines in cometary comae to measure the water production rates, outflow velocity and study effects of collisional quenching in the inner coma. The radio lines at 1667 and 1665 MHz are ideally suited for study of water in comets from the ground, and can be done in daylight. Two short-period comets and two long-period comets are available in this time period. Top
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Spectral line searches at lambda=40cm towards galactic sources (A2621)
PI òÀÓ Dr. Henrik A.O. Olofsson, Onsala Space Observatory
Co-PI òÀÓ Dr. Mikael Lerner
Proposal Date: February 4th, 2011
Abstract: We propose to perform deep searches for a few low-energy lines from molecules such as vinyl cyanide and 13-methanol towards multiple galactic molecular cloud types in the 700-800 MHz frequency range before the RFI environment deteriorates. The hope is to better understand line formation at low frequencies and to find scientific targets for future large instruments with much higher spatial resolution, such as the SKA. Top
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A truly promising attempt to discover 6.7 GHz methanol masers outside the Local Group (A2622)
PI òÀÓ Dr. Andrea Tarchi, INAF - Osservatorio Astronomico di Cagliari
Co-PI òÀÓ Dr. Paola Castangia
Proposal Date: February 4th, 2011
Abstract: Taking profit of the large collecting area of the Arecibo telescope and the availability of the C-high receiver, we propose a very sensitive search for 6.7 GHz methanol masers in a promising sample of nearby galaxies outside the Local Group. The aim of this project is to detect strong Galactic-type CH3OH masers in the closest galaxies of the sample and to investigate the possible existence in any of the target galaxies of methanol kilomaser and megamaser sources, like those produced by H2O and OH. Any detection would constitute the first confident discovery of a methanol maser outside the Local Group and would open up the chance for interferometric follow-ups aimed at deriving proper motions and distances of galaxies. Top
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A search for radio emission from ultracool dwarfs (A2623)
PI òÀÓ Dr. Alexander Wolszczan, Penn State University
Co-PI òÀÓ Dr. Matthew Route
Proposal Date: February 4th, 2011
Abstract: We propose to continue our nearly completed pilot project (a2471) and use the Arecibo telescope with its C-band receiver and the Mock spectrometer to conduct a survey of ultracool dwarfs in search for a burst component of radio emission from these objects. The design of our search has been guided by the unexpected detection of gigahertz radio emission from several ultracool dwarfs, including our own recent first detection of polarized bursts from a T7 brown dwarf, J1047+21. The objectives of this project are to increase the number of detections of ultracool dwarfs to explore the mechanism of both the magnetic field and the radio emission generation in these objects. We are particularly excited about a possibility to explore the brown dwarf - massive planet boundary using magnetic fields as a diagnostic tool. A possibility to probe magnetic fields of the coolest, lowest-mass dwarfs may shed new light on the much debated transition from brown dwarfs to planets, the associated differences in structure, and the most proper way to distinguish between these two types of objects. Top
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Continuing the Monitoring of High Latitude OH/IR Stars (A2645)
PI òÀÓ Dr. Murray Lewis
Proposal Date: June 1st, 2011
Abstract: This is a proposal to continue the monitoring of OH masers in high latitude OH/IR stars. It is only ever accorded scraps of time, most in the daytime / twilight gaps of the telescope schedule. Nevertheless, it has resulted in a number of discoveries, including the identification of both òÀÜdeadòÀÝ OH/IR stars, stars with revived masers, and a star that has changed from a classic double-peaked to single-peaked spectrum, among others. The proposal seeks to continue this fruitful study, in part by filling in gaps in pulsation-phase coverage that result from the episodic (rather than regular) availability of time. There are two institutional byproducts: (i) more telescope hours are used gainfully, and (ii) OH observations are continued in the 1612 MHz band adjacent to the Iridium satellite band, which helps to maintain the record of this bandòÀÙs importance to astronomers. Top
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Pilot Observations for a Drift-Scan Pulsar Search at 327 Mhz (P1693)
PI òÀÓ Dr. Paulo C. Freire, NAIC
Co-PI òÀÓ Dr. James Cordes
Proposal Date: June 1st, 2002
Abstract: We request 100hr of telescope time to conduct a pilot drift-scan pulsar search using the new 327 MHz Gregorian receiver and the Wideband Arecibo Pulsar Processor (WAPP). Using a 30-MHz band expected to be available from the new receiver, we will be twice as sensitive to nearby low-DM pulsars as the present 430-MHz drift-scan surveys for pulsars with average spectral indices. The number detectable at 327 MHz should increase by at least a factor of 2. If these expectations are confirmed, we intent to propose a more ambitious all-sky 327-MHz drift-scan survey, which would complement future ALFA (Arecibo L-Band Feed Array) pulsar surveys that would favor pulsars with flatter spectra. Top
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An ALFA Pulsar Survey of the Galactic Plane (P2030)
PI òÀÓ Dr. James Cordes, Cornell University
Co-PI òÀÓ Dr. Fernando Camilo
Proposal Date: October 1st, 2004
Abstract: We propose the first year of a large-scale survey of the Galactic plane using ALFA. Primary emphasis will be on the inner Galaxy but we also propose a search of the Galactic anticenter region. AreciboòÀÙs high gain and wide-band spectrometers allow surveys of much greater volumes (per unit solid angle) than the eminently successful Parkes Multibeam Survey, particularly for short-period pulsars. The survey will thus find not only a large sample of pulsars, but also rare objects that are especially useful for probing fundamental aspects of neutron stars, testing theories of gravity, and detecting gravitational backgrounds, among other enterprises. We estimate that with our eventual software processing, we will discover a pulsar about every 1.5 hr of on-sky observing time. In addition, our analysis also will detect transient signals from pulsars that are intermittent or from other kinds of objects. Preliminary observations in 2004 Aug-Sep have yielded discovery of eight new pulsars in a quick-look analysis, including one from detection of its single pulses. Many more are expected in the data we already have. Given the pace of observations so far, our ability to glean from them new pulsar discoveries, and our expectation that full resolution code will complete the processing of precursor-survey data by the end of 2005 January, a comprehensive pulsar survey using existing WAPP spectrometers can be initiated on or after 2005 Feb 1. Top
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Characterizing Rotating Radio Transient J0627+16 (P2558)
PI òÀÓ Dr. David J Nice, Bryn Mawr College
Co-PI òÀÓ Dr. Julia Deneva
Proposal Date: February 11, 2010
Abstract: We request 4 hr of Arecibo time for pulse timing measurements of rotating radio transit (RRAT) J0627+16. This source, discovered in the PALFA pulsar survey during observations of the Galactic anti-center region, rotates with a period of 2.180 s and shows a highly erratic pattern of pulse emission. The proposed observations are part of the PALFA effort to measure of positions and spin-down rates of all newly discovered sources. The new observations will also add to our growing knowledge about the emission properties of RRATs. Top
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Expansion of the NANOGrav Pulsar Timing Array (P2624)
PI òÀÓ Dr. Paul B. Demorest, NRAO
Co-PI òÀÓ Dr. David J. Nice
Proposal Date: February 4, 2011
Abstract: Direct detection of gravitational waves (GW) is a major goal in experimental physics and will revolutionize astrophysics, opening an entirely new spectrum for exploration. Precision pulsar timing stands an excellent chance of being the first method to accomplish this feat. Combining data from many objects into a Pulsar Timing Array (PTA) makes GW detection possible. Increasing the number of pulsars in the array improves sensitivity òÀÓ the detection significance improves approximately linearly with the number of pulsars. Observing more pulsars also helps mitigate intrinsic systematic timing effects. The past year has seen a unexpected and unprecedented number of new millisecond pulsars (MSPs) discovered, due to several ongoing radio sky surveys (GBT 350-MHz surveys; PALFA) and targeted radio searches of Fermi-identified gamma-ray point sources. Here we propose an expansion of our ongoing PTA project to take advantage of these new sources. Top
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PSR J1713+0747 with PUPPI: aiming for the best timing even and a new test of general relativity (P2625)
PI òÀÓ Dr. Paulo C. Freire, MPIfR
Co-PI òÀÓ Dr. Paul Demorest
Proposal Date: February 4th, 2011
Abstract: We request time for precise timing of PSR J1713+0747 with the new broadband coherent dedispersion machine, PUPPI. This should result in the most precise pulsar timing ever achieved. We plan a campaign of dense observations that will greatly improve the precision of the orbital and astrometric parameters and enhance the sensitivity of AreciboòÀÙs timing array to gravitational waves. The improved measurement of the orbital parameters will provide a precise mass value for the pulsar and its companion and greatly improve the precision of a new test of general relativity. The requirements for this (high timing precision and continued timing) are the same as for the detection of gravitational waves. Top
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NANOGrav precision timing: Testing a new ISM correction technique (P2627)
PI òÀÓ Dr. Nipuni T Palliyaguru, West Virginia University
Co-PI òÀÓ Dr. Daniel R Stinebring
Proposal Date: February 4, 2011
Abstract: Gravitational waves may be directly detected within the next decade through precise timing of an array of pulsars. Removal of frequency-dependent ISM effects such as dispersion and scattering delays is a key issue in the detection process. Even though the dispersion phenomenon has been recognized to cause significant fluctuations in the times of arrival (TOAs) of pulses and is addressed in current timing algorithms, scattering remains relatively unexplored. Our simulations show that the method of cyclic spectroscopy (CS) can be used to correct TOAs for the scattering delay of a pulsar signal to high levels of precision. So far this method has been successfully applied in an exploratory manner on Arecibo data of pulsar B1937+21 by Demorest and colleagues. In this proposal, we request time to use the cyclic spectroscopy technique to understand and characterize the scattering effects for millisecond pulsar J1713+0747. Top
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Long-term Timing of the Double Neutron Star PSR B1534+12 (P2628)
PI òÀÓ Dr. Ingrid H Stairs, University of British Columbia
Co-PI òÀÓ Dr. Emmanuel Fonseca
Proposal Date: February 4, 2011
Abstract: Our timing and profile-variation observations of the double-neutron-star binary PSR B1534+12 continue to provide high-precision tests of strong-field gravity and a probe of the general-relativistic geodetic precession rate of the pulsaròÀÙs spin axis. Here we request 6 90-minute observing sessions (approximately LST 1430òÀÓ1600) over the course of the next year to monitor changes in the spin properties of and the dispersion measure to this pulsar. These observations are vital to ensure the long-term quality of the data set on this pulsar. Top
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An L-band Search for Giant Pulses and Radio Transients in Local Group Galaxies (P2647)
PI òÀÓ Dr. Julia Deneva, Arecibo Observatory
Co-PI òÀÓ Dr. Ramesh Bhat
Proposal Date: June 2nd, 2011
Abstract: We propose to conduct a search for giant pulses (GPs) from Crab-like pulsars in M33 and four dwarf spheroidal (dSph) Local Group galaxies. Using the Mock spectrometer will allow us to achieve superior sensitivity to prior extragalactic pulsar surveys at Arecibo due to its wider bandwidth and better response to radio-frequency interference (RFI) compared with older backends. For M33 observations, ALFAòÀÙs multibeam capability will provide large instantaneous coverage as well as enable efficient elimination of false positives due to sporadic RFI. For observations of dSph galaxies, we will use the even wider-bandwidth L-wide receiver. Both receivers are capable of detecting GPs from Crab-like pulsars in our target galaxies. In addition to important science that will be enabled by extragalactic pulsar discoveries (studies of pulsar population and ISM in each galaxy, and probing the IGM), the algorithms that we develop will also be applicable to science planned with next-generation arrays. Top
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Pulsar Mass Measurements (P2653)
PI òÀÓ Dr. Joris P. Verbiest, Max-Planck-Institut fuer Radioastronomie
Co-PI òÀÓ Dr. Paulo C. Freire
Proposal Date: June 2nd, 2011
Abstract: We plan to use the unique sensitivity of the Arecibo telescope to observe the millisecond pulsar PSR J1640+2224 intensively near superior conjunction, and less intensely during the remainder of the orbit, with the objective of measuring the Shapiro delay for this binary millisecond pulsar. This might confirm the first ever neutron star mass below 1 solar mass. However, even if this is not the case, the planned observations will improve our knowledge of the neutron star mass distribution. Top
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Arecibo Radar Observations of Nineteen Near-Earth Asteroids During October 2011-January, 2012 (R2629)
PI òÀÓ Dr. Marina Brozovic, JPL/Caltech
Co-PI òÀÓ Dr. Michael Nolan
Proposal Date: February 4th, 2011
Abstract: We propose to observe 19 near-Earth asteroids via S-band. Due to a high number of exciting objects in period from Oct 2011 to Feb 2012, we propose an ambitious schedule of 153 hours of observing time. Asteroid 2005 YU55 stands out as once-per-decade radar target. This ¸Ü400 m diameter object will be at 0.85 lunar distances (LD) on Nov 8, 2011 and the radar data quality will truly be comparable to a spacecraft flyby. Another outstanding target coming in mid-October is Ganymed, which at 40 km diameter is the largest near-Earth object. In the case of Ganymed, we are particularly interested in satellite search. The third highlight is a binary asteroid 1996 FG3 that has been mentioned as the target of interest for the future space missions. We are also very interested in observing asteroids that have been scheduled as targets in the complementary programs such as Spitzer Space Telescope, Wide-field Infrared Survey Explorer (WISE) or NASA InfraRed Telescope Facility (IRTF). We expect that at least 10 out of 19 radar targets will produce datasets suitable for shape modeling. Top
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Urgent proposal for S-band radar imaging of Near-Earth Asteroid 2011 LC19 (R2661)
PI òÀÓ Dr. Marina Brozovic, JPL/Caltech
Co-PI òÀÓ Dr. Michael Nolan
Proposal Date: August 8th, 2011
Abstract: This is an urgent proposal requesting ¸Ü24 hours of observing time during October and November 2011 for newly discovered potentially hazardous asteroid (PHA) 2011 LC19. The physical characteristics of this object are unknown, except that it has an absolute magnitude of 18.4 and an orbit that closely resembles those of the Jupiter-family comets, raising the question of whether this object might be an inactive comet nucleus. In our radar sample of 273 radar-detected NEAs, there are only ten with T <3.0, the classical threshold to distinguish asteroids from comets. 2011 LC19 has the second lowest Tisserand parameter of any NEA we have ever tried to observe with radar. We assumed that 2011 LC19 has an optical albedo of ¸Ü5%, which, given its absolute magnitude, corresponds to a diameter of ¸Ü1.2 km. We estimate that delay-Doppler images with 7.5 m resolution will put more than 1000 pixels on this object. The resulting dataset will be used to reconstruct the asteroidòÀÙs 3D shape. Top
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Urgent Proposal for Radar Observations of Near-Earth Asteroid (162173) 1999 JU3, Target of the Hayabusa 2 Spacecraft Mission (R2662)
PI òÀÓ Dr. Lance A. M. Benner, JPL
Co-PI òÀÓ Dr. Michael Nolan
Proposal Date: August 24th, 2011
Abstract: We propose three days of S-band radar observations of asteroid 1999 JU3, target of JapanòÀÙs Hayabusa 2 spacecraft mission, which will return samples from this asteroid in 2020. The only opportunity to observe 1999 JU3 with radar prior to arrival by the spacecraft occurs in October, 2011, at a distance of 0.44 AU. The asteroid will be a weak target, but if we detect echoes, we hope to use the radar cross section and circular polarization ratio to constrain the asteroidòÀÙs near-surface bulk density and roughness, which will have important implications for obtaining samples from the asteroidòÀÙs surface. Top