A large age for the pulsar B1757-24 from an upper limit on its proper motion

The "characteristic age" of a pulsar usually is considered to approximate its true age, but this assumption has led to some puzzling results, including the fact that many pulsars with small characteristic ages have no associated supernova remnants. The pulsar B1757-24 is located just beyond the edge of a supernova remnant; the properties of the system indicate that the pulsar was born at the centre of the remnant, but that it has subsequently overtaken the expanding blast-wave. With a characteristic age of 16,000 yr, this implies an expected proper motion by the pulsar of 63-80 milliarcsec per year. Here we report observations of the nebula surrounding the pulsar which limit its proper motion to less than 25 mas/yr, implying a minimum age of 39,000 yr. A more detailed analysis argues for a true age as great as 170,000 yr, significantly larger than the characteristic age. From this result and other discrepancies associated with pulsars, we conclude that characteristic ages seriously underestimate the true ages of pulsars

Localization and broadband follow-up of the gravitational-wave transient GW150914

A gravitational-wave (GW) transient was identified in data recorded by the Advanced Laser Interferometer Gravitational-wave Observatory (LIGO) detectors on 2015 September 14. The event, initially designated G184098 and later given the name GW150914, is described in detail elsewhere. By prior arrangement, preliminary estimates of the time, significance, and sky location of the event were shared with 63 teams of observers covering radio, optical, near-infrared, X-ray, and gamma-ray wavelengths with ground- and space-based facilities. In this Letter we describe the low-latency analysis of the GW data and present the sky localization of the first observed compact binary merger. We summarize the follow-up observations reported by 25 teams via private Gamma-ray Coordinates Network circulars, giving an overview of the participating facilities, the GW sky localization coverage, the timeline, and depth of the observations. As this event turned out to be a binary black hole merger, there is little expectation of a detectable electromagnetic (EM) signature. Nevertheless, this first broadband campaign to search for a counterpart of an Advanced LIGO source represents a milestone and highlights the broad capabilities of the transient astronomy community and the observing strategies that have been developed to pursue neutron star binary merger events. Detailed investigations of the EM data and results of the EM follow-up campaign are being disseminated in papers by the individual teams

Localization and broadband follow-up of the gravitational-wave transient GW150914

A gravitational-wave transient was identified in data recorded by the Advanced LIGO detectors on 2015 September 14. The event candidate, initially designated G184098 and later given the name GW150914, is described in detail elsewhere. By prior arrangement, preliminary estimates of the time, significance, and sky location of the event were shared with 63 teams of observers covering radio, optical, near-infrared, X-ray, and gamma-ray wavelengths with ground- and space-based facilities. In this Letter we describe the low-latency analysis of the gravitational wave data and present the sky localization of the first observed compact binary merger. We summarize the follow-up observations reported by 25 teams via private Gamma-ray Coordinates Network Circulars, giving an overview of the participating facilities, the gravitational wave sky localization coverage, the timeline and depth of the observations. As this event turned out to be a binary black hole merger, there is little expectation of a detectable electromagnetic signature. Nevertheless, this first broadband campaign to search for a counterpart of an Advanced LIGO source represents a milestone and highlights the broad capabilities of the transient astronomy community and the observing strategies that have been developed to pursue neutron star binary merger events. Detailed investigations of the electromagnetic data and results of the electromagnetic follow-up campaign will be disseminated in the papers of the individual teams

The human factor: ecological salience in ornithology and ethno-ornithology

At the heart of the interplay between names and knowledge is the relative salience of different taxa. Hunn (1999) described four, semi-overlapping, kinds of salience: phenotypic, perceptual, cultural, and ecological. Whilst the first three are well documented, Ecological Salience remains largely hypothetical in the literature. In this paper I test Hunn’s concept of Ecological Salience by reference to 3,186 recorded English folk-names of British birds. The numbers of names recorded across 57 species represented in this study range from two (Nightingale) to 180 (Grey Heron). A significant positive correlation is demonstrated between the number of recorded folk names for a species and a measure of ubiquity in the 19th Century. Using original bird census data collected by the author for other purposes in the 1990s in farmland and woodland in Oxfordshire, United Kingdom, I demonstrate an overall correlation across Linnaean species between the number of names, number of monolexic names, and three measures of specific relative abundance and distribution. The percentage of names for a species that are monolexic, which is an indicator of familiarity, also correlated with the relative abundance of species in farmland, but this relationship was driven entirely by species with little recorded folklore. For those taxa with documented significance to 19th century and earlier English folk culture, which tend to carry more names than predicted by ecological ubiquity alone, there was no relationship between the extent of monolexis and the relative abundance of a species. The study suggests that Ecological Salience was a significant driver in bird naming in pre-industrial English folk culture, that more frequently encountered species were more likely to develop an associated folklore, but that an effect of acquired cultural salience operated as a driver of overall specific salience, potentially masking the effects of ecological salience

Homologation reactions of alkanes on transition-metal surfaces

A symposia; a combination of expts. using TAP, and isotopic labeling of hydrocarbons using 11C over metal catalysts has provided useful information about the formation of carbon surface species and their activity. The formation of non-reactive surface species following high temp. CO or CH4 adsorption was shown to be more likely at high temps., and that this was a fairly rapid process. The activation energy for C-C coupling reactions was found to be higher following promotion of a Ru catalyst with V. Differences in n-/iso-ratio between labeled and non-labeled products indicated that different reaction pathways led to the formation of n-hexane and iso-hexan