Simulator for Microlens Planet Surveys

We summarize the status of a computer simulator for microlens planet surveys. The simulator generates synthetic light curves of microlensing events observed with specified networks of telescopes over specified periods of time. Particular attention is paid to models for sky brightness and seeing, calibrated by fitting to data from the OGLE survey and RoboNet observations in 2011. Time intervals during which events are observable are identified by accounting for positions of the Sun and the Moon, and other restrictions on telescope pointing. Simulated observations are then generated for an algorithm that adjusts target priorities in real time with the aim of maximizing planet detection zone area summed over all the available events. The exoplanet detection capability of observations was compared for several telescopes.Comment: Proc. IAU Symp. No. 293 "Formation, detection, and characterization of extrasolar habitable planets", ed. by N. Haghighipour. 4 pages, in pres

Qatar Exoplanet Survey : Qatar-3b, Qatar-4b and Qatar-5b

We report the discovery of Qatar-3b, Qatar-4b, and Qatar-5b, three new transiting planets identified by the Qatar Exoplanet Survey (QES). The three planets belong to the hot Jupiter family, with orbital periods of $P_{Q3b}$=2.50792 days, $P_{Q4b}$=1.80539 days, and $P_{Q5b}$=2.87923 days. Follow-up spectroscopic observations reveal the masses of the planets to be $M_{Q3b}$=4.31$\pm0.47$ $M_{\rm J}$, $M_{Q4b}$=6.10$\pm0.54$ $M_{\rm J}$, and $M_{Q5b}$ = 4.32$\pm0.18$ $M_{\rm J}$, while model fits to the transit light curves yield radii of $R_{Q3b}$ = 1.096$\pm0.14$ $R_{\rm J}$, $R_{Q4b}$ = 1.135$\pm0.11$ $R_{\rm J}$, and $R_{Q5b}$ = 1.107$\pm0.064$ $R_{\rm J}$. The host stars are low-mass main sequence stars with masses and radii $M_{Q3}$ = 1.145$\pm0.064$ $M_{\odot}$, $M_{Q4}$ = 0.896$\pm0.048$ $M_{\odot}$, $M_{Q5}$ = 1.128$\pm0.056$ $M_{\odot}$ and $R_{Q3}$ = 1.272$\pm0.14$ $R_{\odot}$, $R_{Q4}$ = 0.849$\pm0.063$ $R_{\odot}$ and $R_{Q5}$ = 1.076$\pm0.051$ $R_{\odot}$ for Qatar-3, 4 and 5 respectively. The V magnitudes of the three host stars are $V_{Q3}$=12.88, $V_{Q4}$=13.60, and $V_{Q5}$=12.82. All three new planets can be classified as heavy hot Jupiters (M > 4 $M_{J}$).Comment: 13Pages, 8Figure

ROME/REA : a gravitational microlensing search for exoplanets beyond the snow line on a global network of robotic telescopes

Funding: KH acknowledges support from STFC grant ST/R000824/1.Planet population synthesis models predict an abundance of planets with semimajor axes between 1 and 10 au, yet they lie at the edge of the detection limits of most planet finding techniques. Discovering these planets and studying their distribution is critical to understanding the physical processes that drive planet formation. ROME/REA is a gravitational microlensing project whose main science driver is to discover exoplanets in the cold outer regions of planetary systems. To achieve this, it uses a novel approach combining a multiband survey with reactive follow-up observations, exploiting the unique capabilities of the Las Cumbres Observatory global network of robotic telescopes combined with a Target and Observation Manager system. We present the main science objectives and a technical overview of the project, including initial results.PostprintPeer reviewe

The Fifth Data Release of the Sloan Digital Sky Survey

This paper describes the Fifth Data Release (DR5) of the Sloan Digital Sky Survey (SDSS). DR5 includes all survey quality data taken through June 2005 and represents the completion of the SDSS-I project (whose successor, SDSS-II will continue through mid-2008). It includes five-band photometric data for 217 million objects selected over 8000 square degrees, and 1,048,960 spectra of galaxies, quasars, and stars selected from 5713 square degrees of that imaging data. These numbers represent a roughly 20% increment over those of the Fourth Data Release; all the data from previous data releases are included in the present release. In addition to "standard" SDSS observations, DR5 includes repeat scans of the southern equatorial stripe, imaging scans across M31 and the core of the Perseus cluster of galaxies, and the first spectroscopic data from SEGUE, a survey to explore the kinematics and chemical evolution of the Galaxy. The catalog database incorporates several new features, including photometric redshifts of galaxies, tables of matched objects in overlap regions of the imaging survey, and tools that allow precise computations of survey geometry for statistical investigations.Comment: ApJ Supp, in press, October 2007. This paper describes DR5. The SDSS Sixth Data Release (DR6) is now public, available from http://www.sdss.or

Fitting empirical fundamental diagrams of road traffic: A comprehensive review and comparison of models using an extensive data set

Understanding the inter-relationships between traffic flow, density, and speed through the study of the fundamental diagram of road traffic is critical for traffic modelling and management. Consequently, over the last 85 years, a wealth of models have been developed for its functional form. However, there has been no clear answer as to which model is the most appropriate for observed (i.e. empirical) fundamental diagrams and under which conditions. A lack of data has been partly to blame. Motivated by shortcomings in previous reviews, we first present a comprehensive literature review on modelling the functional form of empirical fundamental diagrams. We then perform fits of 50 previously proposed models to a high quality sample of 10,150 empirical fundamental diagrams pertaining to 25 cities. Comparing the fits using information criteria, we find that the non-parametric Sun model greatly outperforms all of the other models. The Sun model maintains its winning position regardless of road type and congestion level. Our study, the first of its kind when considering the number of models tested and the amount of data used, finally provides a definitive answer to the question ``Which model for the functional form of an empirical fundamental diagram is currently the best?''. The word ``currently'' in this question is key, because previously proposed models adopt an inappropriate Gaussian noise model with constant variance. We advocate that future research should shift focus to exploring more sophisticated noise models. This will lead to an improved understanding of empirical fundamental diagrams and their underlying functional forms.ISSN:1524-9050ISSN:1558-001

FitFun: A modelling framework for successfully capturing the functional form and noise of observed traffic flow–density–speed relationships

Measurements of the average properties of vehicular traffic are inherently noisy. The distributions of flow and speed measurements at any particular density are non-Gaussian with density-dependent variance, skewness, and kurtosis. Previous studies have failed to properly account for these complicated noise properties. In remediation, we present FitFun, a general framework for modelling any observed flow–density–speed relationship. Models specified within FitFun incorporate components for both the functional form and the noise. We define three flexible noise model components and we fit 200 different models to a high-quality sample of 10,150 observed urban flow-occupancy relationships. We compare the fits using information criteria and assess fit quality through analysis of the residuals. We find that the non-parametric Sun model for the functional form component combined with a Skew Exponential Power Type III noise component significantly outperforms all of the other models. Interestingly, we find that the city, country, road topology, and detector location have virtually no impact on model performance and fit quality, which is very convenient for model selection. The only factor of relevance from those that we studied is the effective occupancy coverage of the data. We conclude that certain models specified judiciously within FitFun can successfully capture the functional form and noise of observed flow–density–speed relationships without the need to discard data taken during non-stationary conditions. This is particularly advantageous for urban data where stationary traffic conditions are rarely observed

A new milky way dwarf satellite in canes venatici

In this Letter, we announce the discovery of a new dwarf satellite of the Milky Way, located in the constellation Canes Venatici. It was found as a stellar overdensity in the north Galactic cap using Sloan Digital Sky Survey Data Release 5 (SDSS DR5). The satellite's color-magnitude diagram shows a well-defined red giant branch as well as a horizontal branch. As judged from the tip of the red giant branch, it lies at a distance of ~220 kpc. Based on the SDSS data, we estimate an absolute magnitude of Mv ~ -7.9, a central surface brightness of μ0,v ~ 28 mag arcsec -2, and a half-light radius of ~8'.5 (~550 pc at the measured distance). The outer regions of Canes Venatici appear extended and distorted. The discovery of such a faint galaxy in proximity to the Milky Way strongly suggests that more such objects remain to be found