News 2004



Data Processing tests 1-3 completed
The first meeting of the recently-formed Steering Committee of the ongoing Gaia Data Access and Analysis Study (GDAAS) has concluded that the first major phase of testing has been completed successfully. Large-scale mission simulations and data analysis runs have been executed over the last three years, under the responsibility of software engineers at GMV Madrid led by Pedro Perez, astronomers at the University of Barcelona led by Jordi Torra, and using the CESCA (Supercomputing Centre of Catalonia) facilities. A mission duration of 18 months, and simulated data for 200,000 stars distributed over the sky, has been used. Results demonstrate that the `global iterative solution', at the heart of the Gaia data processing challenge, can be implemented as anticipated. The various steps of object matching; source, attitude and calibration updating; and relativistic geometry solution are all included. The system is now being upgraded to a larger-scale run using a more detailed instrument model, and more realistic numerical algorithms. Results for this next phase, GDAAS-2, are expected by June 2005. Naturally, many complications and challenges still lie ahead.



Focal Plane EODM review successful
A successful Test Readiness Review for the Electro-Optical Demonstrator Model (EODM) was held at EADS Astrium (Toulouse) in early December, paving the way for a series of tests to be carried out over the next few months. The EODM, containing 4 back-illuminated Gaia prototype CCDs, is designed to be electronically representative of a portion of the Gaia Astrometric focal plane. The planned testing will demonstrate the feasibility of driving a number of CCDs synchronously in the various Gaia astrometric TDI modes (ASM, AF normal, AF bright star). A custom test facility has been developed by EADS Astrium in order to operate the EODM at 165K in a vacuum chamber whilst providing a moving optical source. The optics are configured to provide a pattern of `stars', each having a Point Spread Function similar to that of the Gaia astrometric telescope. In addition to characterizing key parameters such as electronic noise and centroiding accuracy, CCD features such as TDI length selection and anti-blooming will be evaluated in the most flight representative configuration to-date.



Engineering positions at GEPI/Observatoire de Paris
Two engineering positions have been created at GEPI/Observatoire de Paris for one year with a possibility of renewal for one or two years. The first position deals with the simulation of the spectrograph of the Gaia satellite and the implementation of data analysis algorithms. The second position concerns the data handling on-board the satellite. Further details (in French) are available on the GEPI/Observatoire de Paris Gaia web pages. Closing date for applications is 14 January 2005.



GaiaGrid coordinates binary star simulations
A GASS simulation of Gaia telemetry, corresponding to five years of observations of 1000 astrometric binary stars, has been successfully completed using the GaiaGrid environment. 183 independent jobs were distributed through 23 computing nodes distributed in 8 institutes located in 5 countries. A total of 3.8 million CPU seconds were used for the tasks. 16.5 Gb of data were produced and have been used to populate the GDAAS database in order to test the Astrometric Binary Star Analysis shell algorithm. See Simulation of binary stars: a testbed for Grid computing for further details.



Gaia postdoctoral position at Leiden Observatory
Leiden Observatory invites applications for a postdoctoral research position to work on the preparation of the photometric data analysis for ESA's Gaia mission. The study of the photometric data analysis will lead to the design and development of algorithms that will be used during the operational phase of the Gaia mission. The successful applicant will work with Dr. Anthony Brown and is expected to continue to collaborate in original research in related areas part-time. Further details are available on the Leiden Observatory web pages.



Greek government award to ATHENOGAIA
A Greek programme, ATHENOGAIA, which will support the participation of a Greek team in various Gaia working groups has been awarded a grant of 250,000 Euro from the Greek General Secretariat of Research and Technology. This followed an open call for proposals aimed at encouraging Greek participation in European and International Programmes. The members of the team are D. Sinachopoulos (Double & Multiple Star Working Group), R. Korakitis (Photometry Working Group), M. Kontizas and E. Kontizas (Classification Working Group). The programme will be hosted by the National & Kapodistrian University of Athens.



Gaia postdoctoral position at IoA, Cambridge
In the United Kingdom two posts have been created, for a period of three years, to start developing the data processing pipeline software for the photometric and radial velocity data from Gaia. The posts are financed through an eScience grant from PPARC, and are distributed over Cambridge (1.5) and Leicester (0.5). One post, at the Institute of Astronomy in Cambridge, is currently advertised. This small group, including Floor van Leeuwen as coordinator and manager, is intended to become the core of a much larger UK effort to provide actual data processing software for some of the core tasks of the Gaia satellite.



Symposium closes on a positive note
The Gaia Symposium closed with the Concluding Remarks: Gaia and astrophysics in 2015-20 delivered by Tim de Zeeuw (Leiden Observatory). Reviewing the scientific missions planned for the forthcoming decade and considering the major questions to be addressed by these projects de Zeeuw concluded that the science case for Gaia remains very broad and strong as long as the scientific specifications for the mission are maintained. De Zeeuw also noted that tremendous progress had been made in the past four years, much of this effort being funded locally. A short report on the Symposium is also available online.



Gaia Symposium opens at Observatoire de Paris
"The Three Dimensional Universe with Gaia", a symposium dedicated to ESA's Gaia mission, opens today at the Observatoire de Paris, Section de Meudon. The Opening Address is given by Jean Kovalevsky. Programme details can be found on the
symposium web site.



First industrial presentations of Gaia Definition Study
The mid-term presentations of the definition phase for Gaia were held on 14-15 September at ESTEC (see News Item 2004-03-03). Two industrial teams, Alenia/Alcatel and EADS-Astrium, separately presented the current status of their detailed studies into all aspects of the Gaia satellite. These presentations were attended by Gaia's newly appointed Project Manager (Rudi Schmidt), the Gaia Project Scientist, other ESA representatives, and members of the Gaia Science Team. These definition studies will run until mid-2005.



The billion-pixel camera
[From the ESA Space Science web site]
"ESA's 'discovery machine' Gaia is designed to photograph one thousand million stars and hundreds of thousands of other celestial objects, so its camera will have to be something truly special." Read the article.



NWO grant awarded for Gaia photometric analysis study
Recognising the challenge posed by the Gaia data analysis, the Netherlands organisation for scientific research (NWO) has awarded a grant of 364,000 Euro in support of preparations for Gaia photometric data analysis. The award will fund a study, led by Anthony Brown (Leiden University), to advance the plans for the analysis of the photometric data from the Gaia satellite. In addition, and in collaboration with DutchSpace (a company with experience in the application of grid technology to large-scale problems), the study will explore how grid technology can be applied to a realistic, large and complex astronomical investigation, such as that posed by the photometric analysis.



Final programme for Gaia Symposium online
The programme of presentations for the Gaia Symposium, to be held at the Observatoire de Paris-Meudon from 4-7 October, has been finalised. The programme is now
available online on the Symposium website.



FPA and CCD demonstrators - critical design review successful
Under contract to ESA, EADS Astrium (Toulouse) are designing, building and testing two engineering models of the Gaia Astrometric focal plane. The Thermal Mechanical Demonstrator Model (TMDM) is a mock-up of the focal plane structure which will be used for integration and alignment verification, and thermal vacuum testing. The Electro-Optical Demonstrator Model (EODM) is designed to be electronically representative of the flight focal plane. It contains 4 fully-functional CCDs and will be used to assess their performance under nominal operating conditions in the various Gaia TDI modes and for a variety of simulated star magnitudes. The Critical Design Review (CDR) marks the end of the design phase for both of these demonstrator units. Astrium now have formal approval of their designs from ESA and will proceed to integrate the focal plane demonstrators.



ICAP-VS-SA meeting presentations
The classification, variable star, and science alerts working groups held a joint meeting in Cambridge on 15-16 April 2004. The presentations given at the meeting are available on the
Meetings page of the Variable Star Working Group www site and show the current activities, the inter-relationship of the groups, and future plans. Decisions on the algorithms to be implemented in the GDAAS2 data analysis prototype will be made soon.



Gaia photometric filters enter final design phase
The Photometry Working Group has circulated three documents of relevance to the choice of the photometric system design for Gaia, which will be finalised over the next few months: (a) procedures for the photometric system recommendation (Anthony Brown et al, 11 May, PWG-AB-003); (b) scientific targets for the photometric system design (Carme Jordi et al, 14 May, UB-PWG-009); (c) quantification of the target priorities (Carme Jordi et al, 14 May, UB-PWG-015). With the selection of the photometric filters for Gaia now entering the final design phase, all interested parties are invited to provide their comments to the document authors in the coming weeks, to assist convergence of this important activity. Documents are available on Livelink, or from the authors.



Gaia M1 demonstrator successfully sintered
The demonstrator model for the Gaia primary mirror (M1) has been successfully sintered at Boostec facilities, France. The Gaia Large Size SiC Mirror study, led by EADS Astrium, aims to demonstrate the feasibility of the current M1 design by building and testing a replica of the mirror. The study is expected to be completed by mid-2005. (See
Picture of the Week, 2004-05-17)



Final presentation of the RVS instrument study
The first phase of the RVS instrument design has come to an end with the final presentation of the work performed to date by the RVS Consortium. This scientific consortium comprising Mullard Space Science Laboratory, Observatoire de Paris-Meudon, Brunel University, University of Leicester, Osservatorio di Asiago, and University of Ljubljana, and led by Professor Mark Cropper (MSSL), worked with ESA and the industrial System Level Technical Assistance contractors under the direction of ESA Study Manager Oscar Pace. The consortium has refined all aspects of the instrument design (optics, detector, mechanical, thermal, and on-board processing) providing a baseline design for Gaia's radial velocity spectrograph. This will be refined further during the Definition Study phase, extending to mid-2005.



Gaia proceeds to Phase B1
On 2-3 March, separate presentations were made by Alcatel/Alenia and EADS-Astrium to ESA representatives (from the Gaia project and outside) and the Gaia Science Team. Extensive presentations summarised the activities which have been carried out under the parallel System Level Technical Assistance Contracts which have been running with these industrial teams for the past two years. As a result, authorisation has been given for Gaia to enter Phase B1, the detailed definition phase, which is expected to start in April 2004, and which will extend for 1 year. Gaia therefore continues to remain on schedule for a launch in 2010.



Gaia in 2003 - status report now available
Gaia in 2003, a status report prepared by the Gaia Project Scientist, summarises the status of the Gaia project at the end of 2003, describes the progress achieved in 2003, and summarises the major ongoing and planned activities. Gaia in 2003 is now available here (pdf format).



"High Stability Optical Bench" study completed
The final presentation of the Gaia technology "High Stability Optical Bench" contract took place in ESTEC on 3 February. This successfully concluded a two-year study of the basic angle monitoring device (see
Picture of the Week, 2003-11-10). The contract has proved the principles and processes using a laboratory prototype of a device which should ultimately have a 1 microarcsec monitoring capability in orbit. The prototype demonstrated the mounting, alignment, and thermal/vibrational stability of the prototype system manufactured from silicon carbide. The contract was undertaken by EADS-Astrium Toulouse, supported by TNO-TPD Delft for the laboratory set-up, and Boostec for the silicon carbide structure and mirrors (see Picture of the Week, 2003-07-07).



"Ground Verification" study completed
The final presentation of the Gaia technology "Ground Verification" contract took place in ESTEC on 3 February. Along with the final report to be issued shortly, this successfully and satisfactorily brings to an end a one-year industrial study by EADS-Astrium. It studied the objectives and requirements of the ground verification activities which need to be undertaken before launch, including measurement of the optical behaviour at the operational temperature. This is an essential exercise in concluding whether the stringent payload goals can be guaranteed in orbit, and identifying the associated costs and facilities needed. Central to the plans are the projected use of the Focal thermal vacuum facility in Liege, Belgium.



Gaia "stages" at l'Observatoire de Paris Meudon
Three stage positions (temporary training positions) are on offer at l'Observatoire de Paris Meudon. They cover (1) data-reduction of photocentric binary stars, (2) cosmic ray rejection and galaxy detection, and (3) treatment of resolved multiples stars. For further information see t
he original French text, or the English translation.



Gaia at the Model United Nations
An audience of about 800 young adults took time out from debating the hot issues of the day at The Hague International Model United Nations (THIMUN) to enjoy a presentation by Gaia Project Scientist Michael Perryman on "Our Galaxy in 3D". The presentation, to delegates at the Special Conference on The Information Society and The Environment, featured three- dimensional images and movies of the sky generated using Hipparcos data. A lively question and answer session followed the fifty minute talk. See als
o the news item on the ESA Education website.



"Science First Look" study starts at Heidelberg
A small team at Astronomische Rechen-Institut (ARI), Heidelberg, is starting work on a 12-month study investigating the feasibility of using basic science data obtained by the instruments on Gaia as a high-precision indicator of the health of the satellite. This "Science First Look" could provide the possibility of quickly identifying sub-optimal performance in the satellite and of the early correction of mission- critical problems.
re information about the study can be found on the "Gaia at ARI" website.


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