Observations and Implications of the Star Formation History of the LMC

We present derivations of star formation histories based on color-magnitude diagrams of three fields in the LMC from HST/WFPC2 observations. A significant component of stars older than 4 Gyr is required to match the observed color-magnitude diagrams. Models with a dispersion-free age-metallicity relation are unable to reproduce the width of the observed main sequence; models with a range of metallicity at a given age provide a much better fit. Such models allow us to construct complete ``population boxes'' for the LMC based entirely on color-magnitude diagrams; remarkably, these qualitatively reproduce the age-metallicity relation observed in LMC clusters. We discuss some of the uncertainties in deriving star formation histories. We find, independently of the models, that the LMC bar field has a larger relative component of older stars than the outer fields. The main implications suggested by this study are: 1) the star formation history of field stars appears to differ from the age distribution of clusters, 2) there is no obvious evidence for bursty star formation, but our ability to measure bursts shorter in duration than $\sim$ 25% of any given age is limited by the statistics of the observed number of stars, 3) there may be some correlation of the star formation rate with the last close passage of the LMC/SMC/Milky Way, but there is no dramatic effect, and 4) the derived star formation history is probably consistent with observed abundances, based on recent chemical evolution models.Comment: Accepted by AJ, 36 pages including 12 figure

Stellar Populations in Three Outer Fields of the LMC

We present HST photometry for three fields in the outer disk of the LMC extending approximately four magnitudes below the faintest main sequence turnoff. We cannot detect any strongly significant differences in the stellar populations of the three fields based on the morphologies of the color-magnitude diagrams, the luminosity functions, and the relative numbers of stars in different evolutionary stages. Our observations therefore suggest similar star formation histories in these regions, although some variations are certainly allowed. The fields are located in two regions of the LMC: one is in the north-east field and two are located in the north-west. Under the assumption of a common star formation history, we combine the three fields with ground-based data at the same location as one of the fields to improve statistics for the brightest stars. We compare this stellar population with those predicted from several simple star formation histories suggested in the literature, using a combination of the R-method of Bertelli et al (1992) and comparisons with the observed luminosity function. The only model which we consider that is not rejected by the observations is one in which the star formation rate is roughly constant for most of the LMC's history and then increases by a factor of three about 2 Gyr ago. Such a model has roughly equal numbers of stars older and younger than 4 Gyr, and thus is not dominated by young stars. This star formation history, combined with a closed box chemical evolution model, is consistent with observations that the metallicity of the LMC has doubled in the past 2 Gyr.Comment: 30 pages, includes 10 postscript figures. Figure 1 avaiable at ftp://charon.nmsu.edu/pub/mgeha/LMC. Accepted for publication in Astronomical Journa

First-year Sloan Digital Sky Survey-II (SDSS-II) Supernova Results: Hubble Diagram and Cosmological Parameters

We present measurements of the Hubble diagram for 103 Type Ia supernovae (SNe) with redshifts 0.04 < z < 0.42, discovered during the first season (Fall 2005) of the Sloan Digital Sky Survey-II (SDSS-II) Supernova Survey. These data fill in the redshift "desert" between low- and high-redshift SN Ia surveys. We combine the SDSS-II measurements with new distance estimates for published SN data from the ESSENCE survey, the Supernova Legacy Survey, the Hubble Space Telescope, and a compilation of nearby SN Ia measurements. Combining the SN Hubble diagram with measurements of Baryon Acoustic Oscillations from the SDSS Luminous Red Galaxy sample and with CMB temperature anisotropy measurements from WMAP, we estimate the cosmological parameters w and Omega_M, assuming a spatially flat cosmological model (FwCDM) with constant dark energy equation of state parameter, w. For the FwCDM model and the combined sample of 288 SNe Ia, we find w = -0.76 +- 0.07(stat) +- 0.11(syst), Omega_M = 0.306 +- 0.019(stat) +- 0.023(syst) using MLCS2k2 and w = -0.96 +- 0.06(stat) +- 0.12(syst), Omega_M = 0.265 +- 0.016(stat) +- 0.025(syst) using the SALT-II fitter. We trace the discrepancy between these results to a difference in the rest-frame UV model combined with a different luminosity correction from color variations; these differences mostly affect the distance estimates for the SNLS and HST supernovae. We present detailed discussions of systematic errors for both light-curve methods and find that they both show data-model discrepancies in rest-frame $U$-band. For the SALT-II approach, we also see strong evidence for redshift-dependence of the color-luminosity parameter (beta). Restricting the analysis to the 136 SNe Ia in the Nearby+SDSS-II samples, we find much better agreement between the two analysis methods but with larger uncertainties.Comment: Accepted for publication by ApJ

Second Workshop on Estimation with the RDBES data model (WKRDB-EST2; outputs from 2020 meeting)

This report shows how the new RDBES that is currently in development will be better able to support the recast EU Data Collection Framework (Regulation (EU) 2017/1004) than the existing RDB. The RDBES is an essential platform for MS and RCGs to fulfil their obligations towards documenting and improving data quality and designing and implementing regional sampling designs. The evaluation of data precision was performed using two complementary techniques. For relatively simple sampling designs it is possible to use analytical functions to calculate the precision (or a related statistical measure such as variance) of a statistical estimate. These calculations and implementations of them in R code are presented in this report. For more complicated sampling designs, the use of analytical functions is usually not feasible. In these cases, it is necessary to evaluate precision using numerical techniques, the main one of which is bootstrapping. This report discussed when bootstrapping is appropriate and gives several worked examples describing how bootstrapping can be applied in different cases. The evaluation of bias is a difficult subject and is hard to quantify. The approach followed in this report was to build on the previous work available in the ICES literature and identify and enumerate the main common sources of bias in catch sampling programs they describe. The information was collated and an evaluation performed as to whether data stored using the RDBES data format and reports issues from them can inform about the potential for bias in catch estimates. A set of example reports was coded that demonstrates the utility of the RDBES in relation to bias issues and can already help member states to identify how deviations in their sampling programmes and sampling variability may potentially lead to bias in their catch estimates

First-Year Spectroscopy for the SDSS-II Supernova Survey

This paper presents spectroscopy of supernovae discovered in the first season of the Sloan Digital Sky Survey-II Supernova Survey. This program searches for and measures multi-band light curves of supernovae in the redshift range z = 0.05 - 0.4, complementing existing surveys at lower and higher redshifts. Our goal is to better characterize the supernova population, with a particular focus on SNe Ia, improving their utility as cosmological distance indicators and as probes of dark energy. Our supernova spectroscopy program features rapid-response observations using telescopes of a range of apertures, and provides confirmation of the supernova and host-galaxy types as well as precise redshifts. We describe here the target identification and prioritization, data reduction, redshift measurement, and classification of 129 SNe Ia, 16 spectroscopically probable SNe Ia, 7 SNe Ib/c, and 11 SNe II from the first season. We also describe our efforts to measure and remove the substantial host galaxy contamination existing in the majority of our SN spectra.Comment: Accepted for publication in The Astronomical Journal(47pages, 9 figures

Report of the Regional Co-ordination Meeting for the North Sea and Eastern Arctic (RCM NS&EA) 2014

Report of the Regional Co-ordination Meeting for the North Sea and Eastern Arctic (RCM NS&EA) 2014 Swedish University of Agriculture Sciences (SLU Aqua) Lysekil, Sweden 08-12 September 2014The RCM NS&EA met in Lysekil (Sweden) between 8-12 September 2014. The main purpose of the RCM is coordinate the National Programmes (NP) of the Member States (MS) in the North Sea region for 2015

Report of the Regional Co-ordination Meeting for the North Sea and Eastern Arctic (RCM NS&EA) 2013

Report of the Regional Co-ordination Meeting for the North Sea and Eastern Arctic (RCM NS&EA) 2013 final report European Fisheries Control Agency (EFCA) Vigo, Spain 09/09/2013-13/09/2013The Regional Coordination Meeting for the North Sea & Eastern Arctic (RCM NS&EA) was held in September 2013 in Vigo (Spain). The main task of the RCM’s is to coordinate the National Programmes (NP), which propose the national data collection to be carried out by the Member States (MS) under the EU Data Collection Framework (DCF). It was envisaged that, from 2104 onwards, data collection by the MS would be carried out under a new framework (DC-MAP). However, the legislation for this framework is not ready yet. Therefore the Commission has decided to extend the present DCF for the time being and the most recent NPs have been adopted for 2014. Since these NP have been adopted without any changes, there is no need for major coordinatio

Report of the Regional Co-ordination Meeting for the North Sea and Eastern Arctic (RCM NS&EA) 2015

The RCM NS&EA met 31st August - 4th September 2015 at den Haag, Netherlands with 27 participants form 11 member states and autonomous regions attending, including representatives of ICES and the Commission. National correspondents from Spain, UK, Denmark, Lithuania, Germany, Sweden and the Netherlands were present. The meeting was co-chaired by Katja Ringdahl (Sweden) and Alastair Pout (Scotland). The RCM N&SEA considered the recommendations from the 11th Liasion meeting and summaries were presented of the work of expert groups and end users for the 2014-15 period to the plenary session of the meeting. The expert groups included WGCATCH, PGDATA, WKISCON2, WKRDB 2014-01, RDB–SC, STECF and the Zagreb meeting on transversal variables. ICES, as a main end user, provided feedback. A summary was presented of the progress in the regional coordination project (fishPi). This project involves over 40 participants from 12 members states from NS&EA, NA and Baltic regions, two external statistical experts, and ICES. The project has a wide scope of regional cooperation issues including sampling designs, data formats, code lists, PETS, stomach sampling, small scale and recreational sampling, and data quality software production. It has a budget of €400,000, and a one year time line and with a planned completion date of April 2016. A project with identical aims is running in paralleled in the Mediterranean and Black Sea regions The majority of the ToRs of the RCM NS&EA were addressed by three subgroups: one concerned with data analysis, one with the landing obligation, and one with issues particularly related to role and work of national correspondents

The Third Workshop on Population of the RDBES Data Model (WKRDB-POP3)

The aims of this workshop were to explain the data model developed for the commercial fisheries Regional Database and Estimation System (RDBES), assist in populating it with real data for the second test data call for the RDBES, and encourage participants to take part in ongoing testing of the RDBES data submission system. This report documents the progress that participants have done to prepare their institutes for future use of the RDBES system. Some issues with data conversion have been identified and are documented in this report. None of the identified issues are thought to be serious impediments to moving forward with the RDBES development according to the roadmap decided by the Steering Committee of the Regional Fisheries Database in 2020. The RDBES Core Group (the group of people developing the RDBES data model) and ICES Data Centre will look at the results of this workshop and either respond to individual questions or adapt the data model and documentation as required. The workshop concluded and reported before the deadline of the test data call. For a complete test of the data model, all participants were encouraged to complete the data call. A report on the degree of completion of the data call may be expected from WGRDBESGOV which convenes after the data call deadline