81 research outputs found
Easylife: the data reduction and survey handling system for VIPERS
We present Easylife, the software environment developed within the framework
of the VIPERS project for automatic data reduction and survey handling.
Easylife is a comprehensive system to automatically reduce spectroscopic data,
to monitor the survey advancement at all stages, to distribute data within the
collaboration and to release data to the whole community. It is based on the
OPTICON founded project FASE, and inherits the FASE capabilities of modularity
and scalability. After describing the software architecture, the main reduction
and quality control features and the main services made available, we show its
performance in terms of reliability of results. We also show how it can be
ported to other projects having different characteristics.Comment: pre-print, 17 pages, 4 figures, accepted for publication in
Publications of the Astronomical Society of the Pacifi
IVOA Recommendation: SAMP - Simple Application Messaging Protocol Version 1.3
SAMP is a messaging protocol that enables astronomy software tools to
interoperate and communicate.
IVOA members have recognised that building a monolithic tool that attempts to
fulfil all the requirements of all users is impractical, and it is a better use
of our limited resources to enable individual tools to work together better.
One element of this is defining common file formats for the exchange of data
between different applications. Another important component is a messaging
system that enables the applications to share data and take advantage of each
other's functionality. SAMP builds on the success of a prior messaging
protocol, PLASTIC, which has been in use since 2006 in over a dozen astronomy
applications and has proven popular with users and developers. It is also
intended to form a framework for more general messaging requirements
EZ: A Tool for Automatic Redshift Measurement
We present EZ (Easy redshift), a tool we have developed within the VVDS
project to help in redshift measurement from otpical spectra. EZ has been
designed with large spectroscopic surveys in mind, and in its development
particular care has been given to the reliability of the results obtained in an
automatic and unsupervised mode. Nevertheless, the possibility of running it
interactively has been preserved, and a graphical user interface for results
inspection has been designed. EZ has been successfully used within the VVDS
project, as well as the zCosmos one. In this paper we describe its architecture
and the algorithms used, and evaluate its performances both on simulated and
real data. EZ is an open source program, freely downloadable from
http://cosmos.iasf-milano.inaf.it/pandora.Comment: accepted for publication in Publications of the Astronomical Society
of the Pacifi
Data Reduction and Analysis Graphical Organizer
Spectroscopic surveys are undergoing a rapid expansion in their data
collecting capabilities, reaching the level of hundreds of spectra per
pointing. An efficient use of such huge amounts of information requires a high
degree of interconnection between the various tools involved in preparing the
observations, reducing the data, and carrying out the data analysis. DRAGO
(Data Reduction and Analysis Graphical Organizer) attempts to easy the process,
by integrating in a global framework the main data handling components: from
reduction pipelines, to data organization, plotting, and browsing tools, to
storing the data reduction results in a database for further analysis. DRAGO
allows the use of the astronomer own's preferred tools, by "plugging them in"
in an environment which handles transparently the communications between them.
See http://cosmos.mi.iasf.cnr.it/pandora .Comment: 6 pages, 9 figures, ADA III conference proceedin
Spectroscopic surveys:a different approach to data reduction
We present VIPGI, an automatized human supervised reduction environment,
developed within the VIRMOS project to handle VIMOS guaranteed time data. VIPGI
is now offered to the international community to be used on site in Milano and
Marseille. Born to handle the highly multiplexed MOS VIMOS data, it has been
extended to accomodate also IFU data. The widespread and extensive use of VIPGI
has suggested the idea of an integrated environment allowing users not only to
reduce, but also to organize data in logical structures, to insert results in a
database, and use any user defined plugin for data reduction, analysis and
inspection. See http://cosmos.mi.iasf.cnr.it/pandoraComment: Astronomical Data Analysis III conference proceedin
The Data Reduction and Analysis Graphical Organizer
Spectroscopic surveys are undergoing a rapid expansion in their data collecting capabilities, reaching the level of hundreds of spectra per pointing. An efficient use of such huge amounts of information requires a high degree of interconnection between the various tools involved in preparing the observations, reducing the data, and carrying out the data analysis. DRAGO (Data Reduction and Analysis Graphical Organizer) attempts to easy the process, by integrating in a global framework the main data handling components: from reduction pipelines, to data organization, plotting, and browsing tools, to storing the data reduction results in a database for further analysis. DRAGO allows the use of the astronomer own's preferred tools, by "plugging them in" in an environment which handles transparently the communications between them. See http://cosmos.mi.iasf.cnr.it/pandora.
Document type: Conference objec
MASSIV: Mass Assembly Survey with SINFONI in VVDS. VI. Metallicity-related fundamental relations in star-forming galaxies at
The MASSIV (Mass Assembly Survey with SINFONI in VVDS) project aims at
finding constraints on the different processes involved in galaxy evolution.
This study proposes to improve the understanding of the galaxy mass assembly
through chemical evolution using the metallicity as a tracer of the star
formation and interaction history. Methods. We analyse the full sample of
MASSIV galaxies for which a metallicity estimate has been possible, that is 48
star-forming galaxies at , and compute the integrated values of
some fundamental parameters, such as the stellar mass, the metallicity and the
star formation rate (SFR). The sample of star-forming galaxies at similar
redshift from zCOSMOS (P\'erez-Montero et al. 2013) is also combined with the
MASSIV sample. We study the cosmic evolution of the mass-metallicty relation
(MZR) together with the effect of close environment and galaxy kinematics on
this relation. We then focus on the so-called fundamental metallicity relation
(FMR) proposed by Mannucci et al. (2010) and other relations between stellar
mass, SFR and metallicity as studied by Lara-L\'opez et al. (2010). We
investigate if these relations are really fundamental, i.e. if they do not
evolve with redshift. Results. The MASSIV galaxies follow the expected
mass-metallicity relation for their median redshift. We find however a
significant difference between isolated and interacting galaxies as found for
local galaxies: interacting galaxies tend to have a lower metallicity. The
study of the relation between stellar mass, SFR and metallicity gives such
large scattering for our sample, even combined with zCOSMOS, that it is
diffcult to confirm or deny the existence of a fundamental relation
The VIMOS Public Extragalactic Redshift Survey (VIPERS). Never mind the gaps: comparing techniques to restore homogeneous sky coverage
[Abridged] Non-uniform sampling and gaps in sky coverage are common in galaxy
redshift surveys, but these effects can degrade galaxy counts-in-cells and
density estimates. We carry out a comparison of methods that aim to fill the
gaps to correct for the systematic effects. Our study is motivated by the
analysis of the VIMOS Extragalactic Redshift Survey (VIPERS), a flux-limited
survey (i<22.5) based on one-pass observations with VIMOS, with gaps covering
25% of the surveyed area and a mean sampling rate of 35%. Our findings are
applicable to other surveys with similar observing strategies. We compare 1)
two algorithms based on photometric redshift, that assign redshifts to galaxies
based on the spectroscopic redshifts of the nearest neighbours, 2) two Bayesian
methods, the Wiener filter and the Poisson-Lognormal filter. Using galaxy mock
catalogues we quantify the accuracy of the counts-in-cells measurements on
scales of R=5 and 8 Mpc/h after applying each of these methods. We also study
how they perform to account for spectroscopic redshift error and inhomogeneous
and sparse sampling rate. We find that in VIPERS the errors in counts-in-cells
measurements on R<10 Mpc/h scales are dominated by the sparseness of the
sample. All methods underpredict by 20-35% the counts at high densities. This
systematic bias is of the same order as random errors. No method outperforms
the others. Random and systematic errors decrease for larger cells. We show
that it is possible to separate the lowest and highest densities on scales of 5
Mpc/h at redshifts 0.5<z<1.1, over a large volume such as in VIPERS survey.
This is vital for the characterisation of cosmic variance and rare populations
(e.g, brightest galaxies) in environmental studies at these redshifts.Comment: 17 pages, 13 figures, accepted for publication in A&A (revised
version after minor revision and language editing
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