465,152 research outputs found

    Warkworth 12-m VLBI Station: WARK12M

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    This report summarizes the geodetic VLBI activities in New Zealand in 2010. It provides geographical and technical details of WARK12M - the new IVS network station operated by the Institute for Radio Astronomy and Space Research (IRASR) of Auckland University of Technology (AUT). The details of the VLBI system installed in the station are outlined along with those of the collocated GNSS station. We report on the status of broadband connectivity and on the results of testing data transfer protocols; we investigate UDP protocols such as 'tsunami' and UDT and demonstrate that the UDT protocol is more efficient than 'tsunami' and 'ftp'. In general, the WARK12M IVS network station is fully equipped, connected and tested to start participating in regular IVS observational sessions from the beginning of 2011.Comment: 5 pages, 1 figure, Accepeted for the IVS 2010 Annual Repor

    The most and the least avoided consecutive patterns

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    We prove that the number of permutations avoiding an arbitrary consecutive pattern of length m is asymptotically largest when the avoided pattern is 12...m, and smallest when the avoided pattern is 12...(m-2)m(m-1). This settles a conjecture of the author and Noy from 2001, as well as another recent conjecture of Nakamura. We also show that among non-overlapping patterns of length m, the pattern 134...m2 is the one for which the number of permutations avoiding it is asymptotically largest

    High quality ultrafast transmission electron microscopy using resonant microwave cavities

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    Ultrashort, low-emittance electron pulses can be created at a high repetition rate by using a TM110_{110} deflection cavity to sweep a continuous beam across an aperture. These pulses can be used for time-resolved electron microscopy with atomic spatial and temporal resolution at relatively large average currents. In order to demonstrate this, a cavity has been inserted in a transmission electron microscope, and picosecond pulses have been created. No significant increase of either emittance or energy spread has been measured for these pulses. At a peak current of 814±2814\pm2 pA, the root-mean-square transverse normalized emittance of the electron pulses is εn,x=(2.7±0.1)⋅10−12\varepsilon_{n,x}=(2.7\pm0.1)\cdot 10^{-12} m rad in the direction parallel to the streak of the cavity, and εn,y=(2.5±0.1)⋅10−12\varepsilon_{n,y}=(2.5\pm0.1)\cdot 10^{-12} m rad in the perpendicular direction for pulses with a pulse length of 1.1-1.3 ps. Under the same conditions, the emittance of the continuous beam is εn,x=εn,y=(2.5±0.1)⋅10−12\varepsilon_{n,x}=\varepsilon_{n,y}=(2.5\pm0.1)\cdot 10^{-12} m rad. Furthermore, for both the pulsed and the continuous beam a full width at half maximum energy spread of 0.95±0.050.95\pm0.05 eV has been measured

    The Atacama Large Millimeter/submillimeter Array: Overview & status

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    The Atacama Large Millimeter/submillimeter Array (ALMA) is an international radio telescope under construction in the Atacama Desert of northern Chile. ALMA will be situated on a high-altitude site at 5000 m elevation which provides excellent atmospheric transmission over the instrument wavelength range of 0.3 to 3 mm. ALMA will be comprised of two key observing components: an array of up to sixty-four 12-m diameter antennas arranged in a multiple configurations ranging in size from 0.15 to ~14 km, and a set of four 12-m and twelve 7-m antennas operating in closely-packed configurations ~50m in diameter (known as the Atacama Compact Array, or ACA), providing both interferometric and total-power astronomical information. High-sensitivity dual-polarization 8 GHz-bandwidth spectral-line and continuum measurements between all antennas will be available from two flexible digital correlators

    Analysis and evaluation in the production process and equipment area of the low-cost solar array project

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    The attributes of the various metallization processes were investigated. It is shown that several metallization process sequences will lead to adequate metallization for large area, high performance solar cells at a metallization add on price in the range of 6.to12.msquared,or4to6. to 12. m squared, or 4 to .8/W(peak), assuming 15% efficiency. Conduction layer formation by thick film silver or by tin or tin/lead solder leads to metallization add-on prices significantly above the $6. to 12/m squared range c.) The wet chemical processes of electroless and electrolytic plating for strike/barrier layer and conduction layer formation, respectively, seem to be most cost effective

    The PULSE@Parkes project: A new observing technique for long-term pulsar monitoring

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    The PULSE@Parkes project has been designed to monitor the rotation of radio pulsars over time spans of days to years. The observations are obtained using the Parkes 64-m and 12-m radio telescopes by Australian and international high school students. These students learn the basis of radio astronomy and undertake small projects with their observations. The data are fully calibrated and obtained with the state-of-the-art pulsar hardware available at Parkes. The final data sets are archived and are currently being used to carry out studies of 1) pulsar glitches, 2) timing noise, 3) pulse profile stability over long time scales and 4) the extreme nulling phenomenon. The data are also included in other projects such as gamma-ray observatory support and for the Parkes Pulsar Timing Array project. In this paper we describe the current status of the project and present the first scientific results from the Parkes 12-m radio telescope. We emphasise that this project offers a straightforward means to enthuse high school students and the general public about radio astronomy while obtaining scientifically valuable data sets.Comment: accepted for publication by PAS

    The Centaurus Group and the Outer Halo of NGC 5128: Are they Dynamically Connected?

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    NGC 5128, a giant elliptical galaxy only ∼4\sim 4 Mpc away, is the dominant member of a galaxy group of over 80 probable members. The Centaurus group provides an excellent sample for a kinematic comparison between the halo of NGC 5128 and its surrounding satellite galaxies. A new study, presented here, shows no kinematic difference in rotation amplitude, rotation axis, and velocity dispersion between the halo of NGC 5128, determined from over ∼340\sim340 of its globular clusters, and those of the Centaurus group as a whole. These results suggest NGC 5128 could be behaving in part as the inner component to the galaxy group, and could have begun as a large initial seed galaxy, gradually built up by minor mergers and satellite accretions, consistent with simple cold dark matter models. The mass and mass-to-light ratios in the B-band, corrected for projection effects, are determined to be (1.3±0.5)×1012(1.3\pm0.5) \times 10^{12} M_{\sun} and 52±2252\pm22 M_{\sun}/L_{\sun} for NGC 5128 out to a galactocentric radius of 45 kpc, and (9.2±3.0)×1012(9.2\pm3.0) \times 10^{12} M_{\sun} and 153±50153\pm50 M_{\sun}/L_{\sun} for the Centaurus group, consistent with previous studies.Comment: 14 pages, 3 tables, 7 figures, Accepted for publication in A

    Detection of a new methanol maser line with the Kitt Peak 12-m telescope by remote observing from Moscow

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    A new methanol maser line 6(-1)-5(0)E at 133 GHz was detected with the 12-m Kitt Peak radio telescope using remote observation mode from Moscow. Moderately strong, narrow maser lines were found in DR21(OH), DR21-W, OMC-2, M8E, NGC2264, L379, W33-Met. The masers have similar spectral features in other transitions of methanol-E at 36 and 84 GHz, and in transitions of methanol-A at 44 and 95 GHz. All these are Class I transitions, and the new masers also belong to Class I. In two other methanol transitions near 133 GHz, 5(-2)-6(-1)E and 6(2)-7(1)A+, only thermal emission was detected in some sources. Several other sources with wider lines in the transition 6(-1)-5(0)E also may be masers, since they do not show any emission at the two other methanol transitons near 133 GHz. These are NGC2071, S231, S255, GGD27, also known as Class I masers. The ratio of intensities and line widths of the 133 GHz masers and 44 GHz masers is consistent with the saturated maser model, in which the line rebroadening with respect to unsaturated masers is suppressed by cross relaxation due to elastic collisions.Comment: 4 pages, AASTeX text, uses aasms4.sty, 2 Postscript figures, to be published in Ap
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