Variables in the Southern Polar Region Evryscope 2016 Dataset

The regions around the celestial poles offer the ability to find and characterize long-term variables from ground-based observatories. We used multi-year Evryscope data to search for high-amplitude (~5% or greater) variable objects among 160,000 bright stars (Mv < 14.5) near the South Celestial Pole. We developed a machine learning based spectral classifier to identify eclipse and transit candidates with M-dwarf or K-dwarf host stars - and potential low-mass secondary stars or gas giant planets. The large amplitude transit signals from low-mass companions of smaller dwarf host stars lessens the photometric precision and systematics removal requirements necessary for detection, and increases the discoveries from long-term observations with modest light curve precision. The Evryscope is a robotic telescope array that observes the Southern sky continuously at 2-minute cadence, searching for stellar variability, transients, transits around exotic stars and other observationally challenging astrophysical variables. In this study, covering all stars 9 < Mv < 14.5, in declinations -75 to -90 deg, we recover 346 known variables and discover 303 new variables, including 168 eclipsing binaries. We characterize the discoveries and provide the amplitudes, periods, and variability type. A 1.7 Jupiter radius planet candidate with a late K-dwarf primary was found and the transit signal was verified with the PROMPT telescope network. Further followup revealed this object to be a likely grazing eclipsing binary system with nearly identical primary and secondary K5 stars. Radial velocity measurements from the Goodman Spectrograph on the 4.1 meter SOAR telescope of the likely-lowest-mass targets reveal that six of the eclipsing binary discoveries are low-mass (.06 - .37 solar mass) secondaries with K-dwarf primaries, strong candidates for precision mass-radius measurements.Comment: 32 pages, 17 figures, accepted to PAS

Overview and Guidance on Agile Development in Large Organizations

A continual debate surrounds the effectiveness of agile software development practices. Some organizations adopt agile practices to become more competitive, improve processes, and reduce costs. Other organizations are skeptical about whether agile development is beneficial. Large organizations face an additional challenge in integrating agile practices with existing standards and business processes. To examine the effects of agile development practices in large organizations, we review and integrate scientific literature and theory on agile software development. We further organize our theory and observations into a framework with guidelines for large organizations considering agile methodologies. Based on this framework, we present recommendations that suggest ways large organizations with established processes can successfully implement agile practices. Our analysis of the literature and theory provides new insight for researchers of agile software development and assists practitioners in determining how to adopt agile development in their organizations

EVR-CB-001: An evolving, progenitor, white dwarf compact binary discovered with the Evryscope

We present EVR-CB-001, the discovery of a compact binary with an extremely low mass ($.21 \pm 0.05 M_{\odot}$) helium core white dwarf progenitor (pre-He WD) and an unseen low mass ($.32 \pm 0.06 M_{\odot}$) helium white dwarf (He WD) companion. He WDs are thought to evolve from the remnant helium-rich core of a main-sequence star stripped during the giant phase by a close companion. Low mass He WDs are exotic objects (only about .2$\%$ of WDs are thought to be less than .3 $M_{\odot}$), and are expected to be found in compact binaries. Pre-He WDs are even rarer, and occupy the intermediate phase after the core is stripped, but before the star becomes a fully degenerate WD and with a larger radius ($\approx .2 R_{\odot}$) than a typical WD. The primary component of EVR-CB-001 (the pre-He WD) was originally thought to be a hot subdwarf (sdB) star from its blue color and under-luminous magnitude, characteristic of sdBs. The mass, temperature ($T_{\rm eff}=18,500 \pm 500 K$), and surface gravity ($\log(g)=4.96 \pm 0.04$) solutions from this work are lower than values for typical hot subdwarfs. The primary is likely to be a post-RGB, pre-He WD contracting into a He WD, and at a stage that places it nearest to sdBs on color-magnitude and $T_{\rm eff}$-$\log(g)$ diagrams. EVR-CB-001 is expected to evolve into a fully double degenerate, compact system that should spin down and potentially evolve into a single hot subdwarf star. Single hot subdwarfs are observed, but progenitor systems have been elusive.Comment: 14 pages, 11 figures. Published in The Astrophysical Journa

Variables in the Southern Polar Region Evryscope 2016 Data Set

The regions around the celestial poles offer the ability to find and characterize long-term variables from ground-based observatories. We used multi-year Evryscope data to search for high-amplitude (≈5% or greater) variable objects among 160,000 bright stars (mv σ limiting magnitude of g = 16 in dark time. In this study, covering all stars 9 M⊙) secondaries with K-dwarf primaries, strong candidates for precision mass–radius measurements

Evryscope Science: Exploring the Potential of All-Sky Gigapixel-Scale Telescopes

Low-cost mass-produced sensors and optics have recently made it feasible to build telescope arrays which observe the entire accessible sky simultaneously. In this article, we discuss the scientific motivation for these telescopes, including exoplanets, stellar variability, and extragalactic transients. To provide a concrete example we detail the goals and expectations for the Evryscope, an under-construction 780 MPix telescope which covers 8660 sq. deg. in each 2-minute exposure; each night, 18,400 sq. deg. will be continuously observed for an average of ≈6 hr. Despite its small 61 mm aperture, the system's large field of view provides an étendue which is ∼10% of LSST. The Evryscope, which places 27 separate individual telescopes into a common mount which tracks the entire accessible sky with only one moving part, will return 1%-precision, many-year-length, high-cadence light curves for every accessible star brighter than ∼16th magnitude. The camera readout times are short enough to provide near-continuous observing, with a 97% survey time efficiency. The array telescope will be capable of detecting transiting exoplanets around every solar-type star brighter than mV = 12, providing at least few-millimagnitude photometric precision in long-term light curves. It will be capable of searching for transiting giant planets around the brightest and most nearby stars, where the planets are much easier to characterize; it will also search for small planets nearby M-dwarfs, for planetary occultations of white dwarfs, and will perform comprehensive nearby microlensing and eclipse-timing searches for exoplanets inaccessible to other planet-finding methods. The Evryscope will also provide comprehensive monitoring of outbursting young stars, white dwarf activity, and stellar activity of all types, along with finding a large sample of very-long-period M-dwarf eclipsing binaries. When relatively rare transients events occur, such as gamma-ray bursts (GRBs), nearby supernovae, or even gravitational wave detections from the Advanced LIGO/Virgo network, the array will return minute-by-minute light curves without needing pointing toward the event as it occurs. By coadding images, the system will reach V ∼ 19 in 1-hr integrations, enabling the monitoring of faint objects. Finally, by recording all data, the Evryscope will be able to provide pre-event imaging at 2-minute cadence for bright transients and variable objects, enabling the first high-cadence searches for optical variability before, during and after all-sky events

Integrated information increases with fitness in the evolution of animats

One of the hallmarks of biological organisms is their ability to integrate disparate information sources to optimize their behavior in complex environments. How this capability can be quantified and related to the functional complexity of an organism remains a challenging problem, in particular since organismal functional complexity is not well-defined. We present here several candidate measures that quantify information and integration, and study their dependence on fitness as an artificial agent ("animat") evolves over thousands of generations to solve a navigation task in a simple, simulated environment. We compare the ability of these measures to predict high fitness with more conventional information-theoretic processing measures. As the animat adapts by increasing its "fit" to the world, information integration and processing increase commensurately along the evolutionary line of descent. We suggest that the correlation of fitness with information integration and with processing measures implies that high fitness requires both information processing as well as integration, but that information integration may be a better measure when the task requires memory. A correlation of measures of information integration (but also information processing) and fitness strongly suggests that these measures reflect the functional complexity of the animat, and that such measures can be used to quantify functional complexity even in the absence of fitness data.Comment: 27 pages, 8 figures, one supplementary figure. Three supplementary video files available on request. Version commensurate with published text in PLoS Comput. Bio