The twin STEREO spacecraft were launched on October 26, 2006, at 00:52 UT from Kennedy Space Center aboard a Delta 7925 launch vehicle. After a series of highly eccentric Earth orbits with apogees beyond the moon, each spacecraft used close flybys of the moon to escape into orbits about the Sun near 1 AU. Once in heliospheric orbit, one spacecraft trails Earth while the other leads. As viewed from the Sun, the two spacecraft separate at approximately 44 to 45 degrees per year. The purposes of the STEREO Mission are to understand the causes and mechanisms of coronal mass ejection (CME) initiation and to follow the propagation of CMEs through the inner heliosphere to Earth. Researchers will use STEREO measurements to study the mechanisms and sites of energetic particle acceleration and to develop three-dimensional (3-D) time-dependent models of the magnetic topology, temperature, density and velocity of the solar wind between the Sun and Earth. To accomplish these goals, each STEREO spacecraft is equipped with an almost identical set of optical, radio and in situ particles and fields instruments provided by U.S. and European investigators. The SECCHI suite of instruments includes two white light coronagraphs, an extreme ultraviolet imager and two heliospheric white light imagers which track CMEs out to 1 AU. The IMPACT suite of instruments measures in situ solar wind electrons, energetic electrons, protons and heavier ions. IMPACT also includes a magnetometer to measure the in situ magnetic field strength and direction. The PLASTIC instrument measures the composition of heavy ions in the ambient plasma as well as protons and alpha particles. The S/WAVES instrument uses radio waves to track the location of CME-driven shocks and the 3-D topology of open field lines along which flow particles produced by solar flares. Each of the four instrument packages produce a small real-time stream of selected data for purposes of predicting space weather events at Earth. NOAA forecasters at the Space Environment Center and others will use these data in their space weather forecasting and their resultant products will be widely used throughout the world. In addition to the four instrument teams, there is substantial participation by modeling and theory oriented teams. All STEREO data are freely available through individual Web sites at the four Principal Investigator institutions as well as at the STEREO Science Center located at NASA Goddard Space Flight Center.

The STEREO Mission: An Introduction

Astronomical data analysis software and systems

Data Reduction And Error Analysis For The Physical Sciences

Achieving optical gain and/or lasing in silicon has been one of the most challenging goals in silicon-based photonics because bulk silicon is an indirect bandgap semiconductor and therefore has a very low light emission efficiency. Recently, stimulated Raman scattering has been used to demonstrate light amplification and lasing in silicon. However, because of the nonlinear optical loss associated with two-photon absorption (TPA)-induced free carrier absorption (FCA), until now lasing has been limited to pulsed operation. Here we demonstrate a continuous-wave silicon Raman laser. Specifically, we show that TPA-induced FCA in silicon can be significantly reduced by introducing a reverse-biased p-i-n diode embedded in a silicon waveguide. The laser cavity is formed by coating the facets of the silicon waveguide with multilayer dielectric films. We have demonstrated stable single mode laser output with side-mode suppression of over 55 dB and linewidth of less than 80 MHz. The lasing threshold depends on the p-i-n reverse bias voltage and the laser wavelength can be tuned by adjusting the wavelength of the pump laser. The demonstration of a continuous-wave silicon laser represents a significant milestone for silicon-based optoelectronic devices.

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A continuous-wave Raman silicon laser

We must all accept that science is data and that data are science, and thus provide for, and justify the need for the support of, much-improved data curation. (Hanson, Sugden, & Alberts) 
 
Researchers are producing an unprecedented deluge of data by using new methods and instrumentation. Others may wish to mine these data for new discoveries and innovations. However, research data are not readily available as sharing is common in only a few fields such as astronomy and genomics. Data sharing practices in other fields vary widely. Moreover, research data take many forms, are handled in many ways, using many approaches, and often are difficult to interpret once removed from their initial context. Data sharing is thus a conundrum. Four rationales for sharing data are examined, drawing examples from the sciences, social sciences, and humanities: (1) to reproduce or to verify research, (2) to make results of publicly funded research available to the public, (3) to enable others to ask new questions of extant data, and (4) to advance the state of research and innovation. These rationales differ by the arguments for sharing, by beneficiaries, and by the motivations and incentives of the many stakeholders involved. The challenges are to understand which data might be shared, by whom, with whom, under what conditions, why, and to what effects. Answers will inform data policy and practice. © 2012 Wiley Periodicals, Inc.

科研数据共享的挑战 (The Conundrum of Sharing Research Data)

https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2009JA015031

Correction to “An auroral oval at the footprint of Saturn's kilometric radio sources, colocated with the UV aurorae”

Reanalyzing Cassini radio observations performed during Jupiter’s flyby of 2000-2001, we study the internal (rotational) versus external (solar wind) control of Jupiter’s radio emissions, from kilometer to decameter wavelengths, and the relations between the different auroral radio components. For that purpose, we build a database of the occurrence of Jovian auroral radio components bKOM, HOM and DAM observed by Cassini, and then frequency-longitude stacked plots of the polarized intensity of these radio components. Comparing the results obtained inbound and outbound, as a function of the Observer’s or Sun’s longitude, we find that HOM & DAM are dominantly rotation-modulated (i.e. emitted from searchlight-like sources fixed in Jovian longitude), whereas bKOM is modulated more strongly by the solar wind than by the rotation (i.e. emitted from sources more active within a given Local Time sector). We propose a simple analytical description of these internal and external modulations and evaluate its main parameters (the amplitude of each control) for HOM+DAM and bKOM. Comparing Cassini and Nancay Decameter Array data, we find that HOM is primarily connected to the decameter emissions originating from the dusk sector of the Jovian magnetosphere. HOM and DAM components form a complex but stable pattern in the frequency-longitude plane. HOM also seems to be related to the ‘lesser arcs’ identified by Voyager. bKOM consists of a main part above urn:x-wiley:21699380:media:jgra56786:jgra56786-math-000140 kHz in antiphase with HOM occurrence, and detached patches below urn:x-wiley:21699380:media:jgra56786:jgra56786-math-000280 kHz in phase with HOM. The frequency-longitude patterns formed by DAM, HOM and bKOM remain to be modelled.

/pdf/jupiter-s-auroral-radio-emissions-observed-by-cassini-2haix94i17.pdf

Jupiter’s auroral radio emissions observed by Cassini: rotational versus solar wind control, and components identification

Planetary Coordinate Reference Systems for OGC Web Services

Analyzing a database of 26 years of observations of Jupiter from the Nan\c{c}ay Decameter Array, we study the occurrence of Io-independent emissions as a function of the orbital phase of the other Galilean satellites and Amalthea. We identify unambiguously the emissions induced by Ganymede and characterize their intervals of occurrence in CML and Ganymede phase and longitude. We also find hints of emissions induced by Europa and, surprisingly, by Amalthea. The signature of Callisto-induced emissions is more tenuous.

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Radio emission from satellite-Jupiter interactions (especially Ganymede)

[1] Galopeau et al. [2007] (hereinafter referred to as G07) recently presented a study of Saturn Kilometric Radiation (SKR) spectral features observed by Cassini/ Radio and Plasma Wave Science, High-Frequency Receiver (RPWS/HFR), in which they obtained the following results: [2] 1. They propose a classification of the SKR spectrum in three components: component A spans from 3.5 kHz, the lowest-frequency channel of the receiver, to 70–80 kHz; component B is observed from 70–80 kHz to 800–900 kHz; component C lies within the 800–900 kHz to 1200 kHz interval. The physical origin of these components is questioned without answering for components A and C; component B is the well-known auroral SKR [see, e.g., Zarka, 1998]. Galopeau et al. [2007] describe the SKR spectrum morphology especially of B and C components in reference to the morphological classification of Genova et al. [1983], and conclude that the SKR spectrum is variable and unpredictable at time scales of hours to days. [3] 2. They find a weak linear polarization ( 10%) in components A and C, which appear thus to be elliptically polarized, without deciding if it is real or due to inaccurate modeling and/or calibration of the HFR polarization response. [4] 3. They compare their results to the SKR spectrum model of Galopeau et al. [1989]. [5] We comment below on each of these results.

https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2007JA012970

Baptiste Cecconi

Papers

Correction to “An auroral oval at the footprint of Saturn's kilometric radio sources, colocated with the UV aurorae”

Jupiter’s auroral radio emissions observed by Cassini: rotational versus solar wind control, and components identification

Planetary Coordinate Reference Systems for OGC Web Services

Radio emission from satellite-Jupiter interactions (especially Ganymede)

Comment on “Spectral features of SKR observed by Cassini/RPWS: Frequency bandwidth, flux density and polarization” by Patrick Galopeau et al.