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\title{Distributing Planck Simulations on a Grid Structure}
%\title{How the Planck computing needs fit well on a Grid structure}
%\titlemark{Planck simulations and the Grid}
%\titlemark{Planck computing and the Grid}

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\author{Riccardo Smareglia, Fabio Pasian, Claudio Vuerli, Andrea Zacchei}
\affil{INAF - Osservatorio Astronomico di Trieste, Trieste, Italy}

%\author{Daffy Duck\altaffilmark{1}}
%\affil{Astronomy Department, Disney University, Peoria, MA 11111}
%\altaffiltext{1}{Physics Department, The Duck Institute}

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\contact{Riccardo Smareglia} \email{smareglia@ts.astro.it }

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\paindex{Smareglia, R.} 
\aindex{Pasian, F.} 
\aindex{Vuerli, C.}
\aindex{Zacchei, A.}

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\authormark{Smareglia, Pasian, Vuerli \& Zacchei}

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\keywords{Planck, simulations, Grid, Grid: enabled applications}

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\begin{abstract}          % Leave intact
The production of Planck simulated data belongs to a class of
problems which could get a great deal of advantage from their
distribution on to a Grid-enabled environment, and has been
identified by the Planck community as an ideal application to
evaluate the power of the European Grid infrastructure. If the
project is successful, its natural extension goes in the direction
of studying the feasibility of porting large sections of the
Planck data processing on the Grid.
\end{abstract}

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\section{Introduction - The Planck Mission}

Planck is the third Medium-Sized Mission (M3) of ESA's Horizon
2000 Scientific Programme. The mission is designed to image the
anisotropies of the Cosmic Background Radiation Field over the
whole sky, with unprecedented sensitivity and angular resolution,
and it will provide a major source of information relevant to
several cosmological and astrophysical issues, such as testing
theories of the early universe and the origin of cosmic structure.
Planck is scheduled to be launched in February 2007, and two
complete sky surveys are foreseen.The scientific development of
the mission is directed by the Planck Science Team

Planck is composed of two instruments: the High Frequency
Instrument (HFI) and the Low  Frequency Instrument (LFI), operated
by two dedicated Consortia through their Data Processing Centres
(DPCs). The DPCs have in charge to integrate/run the simulation
software contributed by HFI and LFI scientists, process the
simulation results (the output of Planck receivers), build/test a
number of pipelines to be used during operations to process both
technical (House-Keeping) and scientific data. At the end of the
mission DPCs will deliver the following scientific products:
\begin{itemize}
\item Calibrated time series data, for each receiver, after removal
of systematic features and attitude reconstruction
\item Photometrically and astrometrically calibrated maps of the sky
in the observed bands (frequency maps)
\item Sky maps of the main astrophysical components
\item Catalogs of sources detected in the sky maps of the main
astrophysical components
\item Power spectrum of the CMB.
\end{itemize}

\section{Planck simulations and the Grid}

Some development steps are still underway for the Planck mission,
one of which relates to the simulation of the mission outputs,
necessary to forecast the behavior of satellite and instruments
and to prepare the processing tools needed to prepare the
scientific outputs of the mission..

In particular, there is the need to extend the simulation
applications developed up to now to cope with new observational
constraints. Sharing of simulation software, both existing and
being developed, and of simulated data and computing resources to
obtain them, are important as well for the success of a complex
mission such as Planck.

One of the main challenges is the ability to design of a system,
integrated while distributed across different sites, capable of
generating at the production level different simulated skies
depending on different instrumental configurations or behaviors.
Planck simulations and processing are therefore an ideal
application to evaluate the power of the European Grid
Infrastructure.

\subsection{A Possible Scenario}

A possible scenario can be sketched for a Grid-enabled simulation
environment for Planck: the Planck user requests to download,
through a user interface, a specific set of all-sky simulated data
under certain scientific hypotheses, and using a selected mission
and instrument configuration; the environment understands if such
a simulation has been already produced and, if so, it allows the
user to access the data; if no data are available, then suitable
computing facilities should be selected from a pool of available
resources to produce the data the user will eventually be able to
access; data could be processed locally or, if needed, in a
distributed way throughout the Grid once again by selecting the
computing facilities from those available on the Grid
infrastructure.

\subsection{The Grid-enabled application }

The Grid-enabled application is based on a suite of
already-existing applications developed by a set of institutes
collaborating in the framework of the Planck ESA mission. Such
applications, running on separate local computing facilities,
simulate the microwave sky, produce time series of Planck data,
and process the simulated data. The exercise would be generating a
Gridified Simulation Pipeline whose components are the
already-existing applications after they have been successfully
ported on the Grid infrastructure.

The tasks provided by the application (the Gridified Pipeline) is
planned to be: the generation of a microwave sky by tuning a set
of input parameters (e.g. noise and systematic effects
introduction) the extraction of time series simulating Planck
``observations'' of the generated sky

The key purpose is to make possible a profitable usage of the Grid
infrastructure by the Planck collaboration to run the simulations
code, and, if possible, the whole data processing for the mission
during operations. The main objectives of the application are:
\begin{enumerate}
\item To prove the feasibility of the interfacing and porting of the
simulation applications on a Grid environment
\item To prove the
feasibility of new applications interfaced with the Grid
\item To
prove the feasibility of a system allowing management of the
existing simulated data and production of new ones
\item To prove the
feasibility of porting the whole Planck data processing structure,
or a fraction thereof, onto a Grid environment
\item Training and
dissemination activities to create grid competence and awareness
in different groups of the Planck community
\end{enumerate}

\subsection{Added Value}

There are a number of advantages in using Grid-enabled software to
run Planck simulations. Simulations code and produced simulated
data are transparently and easily accessible to the Planck
community through the Grid UI. They can ask for specific simulated
data and, in case, run the application (the Simulations Pipeline)
to produce them. Pipeline runs may require considerable computing
power capabilities: by using the Grid, pipeline runs will be
disseminated over the continental Grid infrastructure so that
computing power shortages of single institutes can be easily
overcome. Moreover, computing resources exploitation is optimized.
Simulated data may be remarkable in size (e.g. frequency and
component maps, especially time series may be huge). Simulations
results may be transparently spread over different Storage
Elements (SEs) and, from them, retrieved by the gridified
Pipeline. Because of their intrinsic parallelism, simulations
applications should gain great advantage when run over the Grid
infrastructure.

\subsection{Problems/Requirements}

There are some limitations in running Planck applications on a
Grid-enabled environment. Access to simulations software and
produced simulated data of the HFI and LFI Consortia is not free.
The Planck-specific Integrated Data and Information System (IDIS)
infrastructure provides a federation layer having in charge the
access control to the Planck information system; only authorized
users can access the information system. Each IDIS user has a user
profile defining his/her privileges Therefore, it is necessary
that the IDIS federation layer is integrated with the Grid user
certification and authorization mechanism

Moreover, a web-based Grid User Interface (UI) could be
necessary/desirable to make the simulated data retrieval and the
simulated pipeline job submission easy. It shall be possible to
interface several DBMS via the Grid-UI.

It is finally to be noted that, at present, simulated data are
stored in FITS format, however in the near future the original
data will be stored on a commercial database management system
(Versant is the current baseline). This may imply some licensing
issues.

\section{Conclusions and Further Tasks}

The production of Planck simulated data has been identified as an
ideal application to evaluate the power of the European Grid
infrastructure in solving this class of problems. It will
therefore be proposed to the EGEE project as one of the
applications of the astrophysical community to be used as a
test-bed for the EGEE infrastructure. This is an astronomy
application that is more in the spirit of the computational grid,
rather than the data grid, which fits more with the Virtual
Observatory concepts.

A natural extension of the project goes in the direction of global
processing. A further  step is thus foreseen to be studying the
feasibility of porting the whole Planck data processing
infrastructure on to a Grid environment. In this case, the
construction of photometrically and astrometrically calibrated
frequency maps of the sky in the observed bands, the construction
of sky maps of the main astrophysical components and the
population of a catalog of sources detected in the sky maps of the
main astrophysical components could be applications to be
Grid-enabled in the near future.

% You can also add an acknowledgments section as indicated below.

\acknowledgments

The authors wish to thank a number of colleagues with whom the
idea of distributing Planck simulations on a Grid environment was
discussed. Among these, Anthony Banday, Matthias Bartelmann,
Leopoldo Benacchio, Fran\c cois Bouchet, Kari Enqvist, Andrew
Jaffe, Bob Mann, Enrique Martinez-Gonzalez, Rafael Rebolo,
Jean-Fran\c cois Sygnet. The authors are members of the Planck/LFI
Consortium, led by Reno Mandolesi.

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\reference Bennett, K., Pasian, F., Sygnet, J.F., Banday, A.J.,
Bartelmann, M., Gispert, R., Hazell, A., O'Mullane, W., Vuerli C.\
2000,\ in: Advanced Global Communications Technologies for
Astronomy, SPIE proceedings 4011, p. 2-10

\reference Lama, N., Vuerli, C., Smareglia, R., Gasparo, F.,
    Pasian, F., Genghini, M.\ 2004, \adassxiii, \paperref{P4-9}

\reference Pasian, F., Smareglia, R., Vuerli, C., Zacchei, A.,
Lama, N., Benacchio, L.\ 2003,\ Mem. S.A.It. Supplements, in press

\reference Pasian, F., Sygnet, J.F.\ 2002,\ in: Data Analysis II,
SPIE proceedings 4847, p.158-169 p. 25-34


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