13 research outputs found

    Planck pre-launch status: calibration of the Low Frequency Instrument flight model radiometers

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    The Low Frequency Instrument (LFI) on-board the ESA Planck satellite carries eleven radiometer subsystems, called Radiometer Chain Assemblies (RCAs), each composed of a pair of pseudo-correlation receivers. We describe the on-ground calibration campaign performed to qualify the flight model RCAs and to measure their pre-launch performances. Each RCA was calibrated in a dedicated flight-like cryogenic environment with the radiometer front-end cooled to 20K and the back-end at 300K, and with an external input load cooled to 4K. A matched load simulating a blackbody at different temperatures was placed in front of the sky horn to derive basic radiometer properties such as noise temperature, gain, and noise performance, e.g. 1/f noise. The spectral response of each detector was measured as was their susceptibility to thermal variation. All eleven LFI RCAs were calibrated. Instrumental parameters measured in these tests, such as noise temperature, bandwidth, radiometer isolation, and linearity, provide essential inputs to the Planck-LFI data analysis.Comment: 15 pages, 18 figures. Accepted for publication in Astronomy and Astrophysic

    Planck pre-launch status: Low Frequency Instrument calibration and expected scientific performance

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    We give the calibration and scientific performance parameters of the Planck Low Frequency Instrument (LFI) measured during the ground cryogenic test campaign. These parameters characterise the instrument response and constitute our best pre-launch knowledge of the LFI scientific performance. The LFI shows excellent 1/f1/f stability and rejection of instrumental systematic effects; measured noise performance shows that LFI is the most sensitive instrument of its kind. The set of measured calibration parameters will be updated during flight operations through the end of the mission.Comment: Accepted for publications in Astronomy and Astrophysics. Astronomy & Astrophysics, 2010 (acceptance date: 12 Jan 2010

    N-(2-Carboxyethyl)-2,5-dideoxy-2,5-imino-D-mannonic acid [(3R,4R,5R)-1-(2-carboxyethyl)-3,4-dihydroxy-5-hydroxymethyl-L-proline]

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    The absolute stereochemistry of the title compound, C9H 15NO7, was determined from the use of D-glucuronolac-tone as the starting material. The compound crystallizes as the zwitterion. The five-membered ring adopts an envelope conformation with the -CH 2OH-substituted C atom forming the flap. An intramolecular N - H···O hydrogen-bond occurs. In the crystal, the compound exists as a three-dimensional O - H···O intermolecular hydrogen-bonded network with each molecule acting as a donor and acceptor for four hydrogen bonds

    Authority of Law

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    Law transforms our lives in the most important way: it changes how we act and because of this it gives rise to fundamental questions. One such question concerns legal authority and individual autonomy and asks; if we are autonomous agents how do legislators, judges and officials have legitimate authority to change our actions and indirectly change how we conduct our lives? We conceive ourselves as active agents who determine how and when to act, and we conceive ourselves as the planners of our own lives and the creators of change. Law asks us, however, to perform actions that range from the trivial to the complex. But how is it possible for me to do, in full awareness, as the law asks and, at the same time, be in control of my own destiny? How is my free will affected by the law

    Planck-LFI: Instrument Design and Ground Calibration Strategy

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    The ESA Planck satellite is designed to achieve precision imaging of the Cosmic Microwave Background with an unprecedented combination of angular resolution, sensitivity, spectral range and sky coverage. The Low Frequency Instrument is one of two complementary instruments, and covers 30, 44, and 70 GHz with an array of wideband pseudo-correlation, cryogenic radiometers. Advanced qualification models of the radiometer chains and of the instrument electronics have been manufactured, tested and integrated into the LFI Qualification Model. The main radiometer calibration, RF tuning and performance characterization is carried out at a single radiometer chain level, and then verified at instrument integrated level in dedicated cryofacilities. Here we describe the main requirements and instrument design, and we summarize the radiometer calibration strategy optimised during the qualification activity in view of the LFI Flight Model campaign
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