The WASP consortium operates two wide-field camera arrays in the northern (La Palma) and southern (Sutherland) hemispheres. Each installation comprises a robotic mount bearing 8 cameras, forming a mosaic with a field of view of 30 degrees in declination by 1 hour in right ascension. Here we describe the system performance, observing strategy, candidate selection procedures and follow-up campaigns, and the yield and physical characteristics of the 16 planets discovered in the course of the survey to date.

A grating monochromator has been flown from Aire sur l'Adour (Landes) on May 10, 1968, April 19, 1969 and October 3, 1969. The instrumentation and the experimental procedure have been described previously (Ackerman et al., 1968) as well as the results of the first flight. For the two subsequent flights the wavelength marking was improved by increasing the number of the telemetered wavelength marking pulses. For the last flight the FM-FM analog telemetry system was replaced by a PCM telemetry system in such a way that the data analysis was completely made by means of a computer. Float altitudes were respectively 34, 38 and 37 km. From 1850 Å to 3000 Å up to 90 spectra per flight of the solar radiation penetrating into the atmosphere were telemetered to the ground. The solar zenith distance was ranging from 30° to 60°. The equivalent slit width was equal to 19 Å in the case of the first experiment and was equal to 14.6 Å for the two subsequent flights.

We started a comparison between different NLTE codes that calculate the statistical equilibrium in solar-type and late type stars (G - A type stars). Discrepancies between different authors analyzing the statistical equilibrium of the same element in the same atmosphere are often surprisingly large. Hence, this study was meant to nail down the origin of these differences. The preliminary results indicate that even if the atmosphere and the atomic input data is fixed, discrepancies of up to 40% in the outer atmospheric layers are still present; the main reason is the different treatment of the background opacity. Following up, we shortly discuss the completeness and accuracy of atomic data used in analyses of the kinetic equilibrium of atoms in the atmospheres of middle and late type stars.

We report here preliminary results of observations of the quasar 3C147 which were made at 6 cm with a resolution of about 1 milliarcsecond using a VLB interferometer system with four antennas in the USA and one in Europe. Our observations are shown in Figure 1 along with previously published maps on larger size scales. VLA observations made at 2 cm wavelength (Fig. 1a) show an extended feature lying about 0.5 arc-seconds (3.5 kpc) to the northeast of a bright core (Readhead et al. 1980), while VLBI observations made at 18, 50, and 91 cm (Readhead and Wilkinson 1980, Wilkinson et al. 1977, and Simon et al. 1980) show a jet-like feature extending about 0.2 arcsec (1 kpc) in the opposite direction (Fig. 1b). The 18 cm VLB observations also indicated the presence of a smaller elongated feature extending only 3 milliarcseconds (20 pc) again toward the northeast (Fig. 1c). We have observed 3C147 in March 1978 and again in April 1981 with a resolution of 0.7 and 1.5 milliarcsec respectively. The 1981 data (Fig. 1d) clearly show the double structure of the core as well as a lower surface brightness feature which can also be seen in the 18 cm map. Our 1978 data (Fig. 1e) has better resolution and shows considerable structure in the milliarcsec component, but due to the absence of phase information in these data, the details are not reliable and the orientation is uncertain by 180°. The orientation is, however, specified by reference to the 1981 data.

Simulations of cellular magnetoconvection in a compressible fluid reveal the formation of magnetic structures with a substantial bipolar component as an inherent property of the topology of cellular flows.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We discuss the properties of the very energetic Type Ic supernovae (SNe Ic) 1998bw and 1997ef, and of Type IIn supernova (SN IIn) 1997cy. SNe Ic 1998bw and 1997ef are characterized by their large luminosity and very broad spectral features. Their observed properties can be explained if they are very energetic SN explosions (EK ≳ 1 × 1052 erg), originating probably from the core collapse of the bare C+O cores of massive stars (~ 30–40M⊙). At late times, both the light curve and the spectra suggest that the explosion may have been asymmetric; this may help us understand the claimed connection with GRBs. Type IIn SN 1997cy is even more luminous than SN 998bw, and the light curve declines more slowly than the 56Co decay. We model such a light curve with circumstellar interaction, which requires the explosion energy of ~ 5 × 1052 erg. Because these kinetic energies of explosion are much larger than in normal core-collapse SNe, we call objects like these SNe “hypernovae”.

We have recently hit the milestone of 5,000 exoplanets discovered. In stark contrast with the Solar System, most of the exoplanets we know to date orbit extremely close to their host stars, causing them to lose copious amounts of gas through atmospheric escape at some stage in their lives. In some planets, this process can be so dramatic that they shrink in timescales of a few million to billions of years, imprinting features in the demographics of transiting exoplanets. Depending on the transit geometry, ionizing conditions, and atmospheric properties, a planetary outflow can be observed using transmission spectroscopy in the ultraviolet, optical or near-infrared. In this review, we will discuss the main techniques to observe evaporating exoplanets and their results. To date, we have evidence that at least 28 exoplanets are currently losing their atmospheres, and the literature has reported at least 42 non-detections.

A significant fraction of white dwarfs possess a magnetic field with strengths ranging from a few kG up to about 1000 MG. However, the incidence of magnetism varies when the white dwarf population is broken down into different spectral types providing clues on the formation of magnetic fields in white dwarfs. Several scenarios for the origin of magnetic fields have been proposed from a fossil field origin to dynamo generation at various stages of evolution. Offset dipoles are often assumed sufficient to model the field structure, however time-resolved spectropolarimetric observations have revealed more complex structures such as magnetic spots or multipoles. Surface mapping of these field structures combined with measured rotation rates help distinguish scenarios involving single star evolution from other scenarios involving binary interactions. I describe key observational properties of magnetic white dwarfs such as age, mass, and field strength, and confront proposed formation scenarios with these properties.

This communication is devoted to data processing of images obtained using an extreme adaptive optics (AO) system and a coronagraph. Specific attention is given to the following degrading factors: the residuals of atmospheric turbulence after AO correction and the “side” effects of the coronagraph. Relying on a statistical modeling of the measurements a test based on short exposure images is proposed. This processing, which generalizes the dark-speckle technique, takes into account the “local” variance of the complex amplitude residuals and the deterministic response of the system (i.e. without atmospheric turbulence).

Black widows and redbacks are binary systems consisting of a millisecond pulsar in a close binary with a companion having matter driven off of its surface by the pulsar wind. X-rays due to an intrabinary shock have been observed from many of these systems, as well as orbital variations in the optical emission from the companion due to heating and tidal distortion. We have been systematically studying these systems in radio, optical and X-rays. Here we will present an overview of X-ray and optical studies of these systems, including new XMM-Newton and NuStar data obtained from several of them, along with new optical photometry.

Magnetic reconnection plays a central role in the interpretation of a wide variety of observed solar, space, astrophysical, and laboratory plasma phenomena. The relatively recent discovery that reconnection is common at thin current sheets in the solar wind opens up a new laboratory for studying this fundamental plasma process and its after-effects. Here we provide a brief overview of some of the new insights on reconnection derived from observations of reconnection exhaust jets in the solar wind.

We present a weak lensing analysis and comparison to optical and X-ray maps of the close pair of massive clusters A222/223. Indications for a filamentary connection between the clusters are found and discussed.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

NRAO 140 is a quasar (z = 1.258) which is among only 3 or 4 such objects (and the one with the highest z) which were detected at X-ray energies prior to the operation of the Einstein Observatory (Marscher et al. 1979). We obtained contemporaneous X-ray and radio VLBI observations of the source in early 1980, to determine whether Compton scattering within the radio source is the primary X-ray emission mechanism (Marscher and Broderick 1981b). Instead, we found that the radio parameters predicted more than 103 times more X-ray flux than was observed. Since the Compton calculation is independent of distance, and since the troublesome component was partially resolved (and hence not a high-brightness-temperature emitter), we found that relativistic motion aimed nearly directly toward the observer with Lorentz factor exceeding 4, needed to be invoked in order to bring the predicted Compton flux down to the observed level (Marscher and Broderick 1981a, b). Since relativistic motion is also the preferred explanation for the apparent superluminal expansion seen in some compact radio sources (e.g., M. Cohen, this volume; Marscher and Scott 1980; Kellermann and Pauliny-Toth 1981), we predicted that the compact components in NRAO 140 should appear to separate at a speed exceeding about 4c.

We have constructed solid Fabry-Pérot narrow-band filters that can be used in systems having one arc second or better resolution. Our filters operate at Hα, have a three-inch aperture, and typical transmission of 70%. However, the same technology can be applied to construction of filters as narrow as 0.05 Å at any wavelength from 4200 to 11000 Å.

Within the near-Earth object population, one finds asteroids, comets, and meteorites thereby placing the NEO population at the center of the ACM conference. The longstanding gulf between the spectral properties of S-type asteroids and ordinary chondrite meteorites appears to be bridged, where the observational data are consistent with a space weathering type process. As much as 30% of the entire NEO population may reside in orbits having a Jovian Tisserand parameter <30, and among these roughly half are observed to have comet-like physical properties in terms of their albedos and spectra (taxonomy). Thus 15±5% of the entire NEO population may be comprised by extinct or dormant comets.

The IAU Strategic Plan for 2020-2030 presents an overview of all of the activities of the IAU along with priorities, key goals, mandates, and specific actions. Here future plans and goals are outlined for the Office of Astronomy for Development (OAO).

We present preliminary results of our HST-WFPC2 pc-survey of Wolf-Rayet stars. Initiated in 1996, the goal was to discover new companions to, and cluster/association memberships of, known Galactic WR stars. From these results, Niemela et al. (1998) have already established a firm link between non-thermal radio emission and the location of binary wind-collision zones for WR 146 (confirming radio data of Dougherty et al. 1996) and WR 147 (confirming radio and IR data of Williams et al. 1997; see also Williams, these Proceedings), and confirmed the presence of a binary companion for WR 86 (listed by Jeffers et al. 1963). Here, for the first time, we present new information on WR38, WR38a, and WR 104.

The SL9 impacts are known by their plumes. Several of these were imaged by HST towering 3000 km above Jupiter's limb. The heat released when they fell produced the famous infrared main events. The reentry shocks must have been significantly hotter than the observed color temperature would imply, which indicates that the shocks were radiatively cooled, and that most of the energy released on reentry was radiated. This allows us to use the infrared luminosities of the main event to estimate the energy of the impacts; we find that the R impact released some 0.3 — 1 x 1027 ergs. Shock chemistry generates a suite of molecules not usually seen on Jupiter. The chemistry reflects a wide range of different shock temperatures, pressures, and gas compositions. The primary product, apart from H2, is CO, the yield of which depends only weakly on the comet's composition, and so can be used to weigh the comet. Abundant water and S2 are consistent with a somewhat oxidized gas (presumably the comet itself), but the absence of SO2 and CO2 shows that conditions were neither too oxidizing nor the shocks too hot. Meanwhile, production of CS, CS2, and HCN appears to require a source in dry jovian air; i.e., the airbursts occurred above the jovian water table. Tidal disruption calculations and models of the infrared light curves agree on an average fragment diameter of about half a kilometer. Chemical products and atmospheric disruption models agree on placing the terminal explosions around the 1 to 4 bar levels. The plumes were spectacular because the explosions were shallow, not because the explosions were large.

The continuum radio spectra of planetary nebulae are discussed, and the structure of these objects is examined from the observed aperture synthesis brightness distributions determined with the Very Large Array. The use of radio observations in determining distances to planetary nebulae is examined. The detection of atomic neutral hydrogen at λ21 cm associated with planetary nebulae, as well as the associated CO and OH components are discussed. An upper limit, of the nebular magnetic field associated with the neutral material, of 1mG is reported for NGC 6302.

The size, and therefore the importance, of the population of compact, steep-spectrum, radio sources has only recently been recognised. While it is now clear that the extended steep-spectrum sources are powered by a pair of, originally anti-parallel, beams which transport energy to the outer lobes some 105–106 parcsec away, our understanding of the compact steep-spectrum sources is almost nil. This is largely because our radio maps have not had high enough resolution to show their structures in any detail. However 1.67 and 5 GHz MERLIN observations (resolutions 0″.25 and 0″.1) of the ~20 steep-spectrum 3CR sources whose LAS is ≲2″ have now allowed us to classify their structures, at least in broad terms. These MERLIN maps, and recent VLBI maps, show that while there is a wide range of structures - from colinear doubles to amorphous “blobs” - the “peculiar” structures are strongly concentrated in the objects whose optical counterparts are called QSO's.