(2006-06-02) Concept for quick data delivery produced:

(2006-05-20) Gaia Data Processing and Analysis Consortium (DPAC) formally created:

(2006-05-19) Schedule for ESA's Announcement of Opportunity for the Gaia data reduction

(2006-05-17) Gaia Science Management Plan essentially approved

(2006-05-02) Astrometric Global Iterative Solution "test bed" running at ARI

(2006-04-11) Gaia Science Management Plan

(2006-02-28) Gaia CU3 meeting

(2006-02-13) New team member

(2006-02-09) Gaia has the final "go"!

(2006-01-27) ARI's "Gaia professor" coming

(2006-01-24) Good prospects for Gaia

(2006-01-13) Gaia prime contractor recommendation

(2005-12-09) Gaia CU3 meeting

(2005-11-04): Gaia CU3 meeting

(2005-10-26) Several meetings scheduled

(2005-10-18) New team member

(2005-09-15) Resumption of the "current topics" column

(2005-09-14) Ground Segment / First Look coordination meeting

(2005-09-12) Different method yields identical results

(2005-08-02) First Look concept study completed

(2005-08-01) Gaia enters the industrial implementation phase

(2005-06-17) Leading positions for Heidelberg astronomers

(2005-04-22) Gaia data reduction consortium under construction

(2005-11-02) RVS / FL meeting on Dec. 2

(2005-04-19) A movie from the Gaia First Look study

(2005-04-15) Gaia data reduction - `Letters of Intent' to ESA

(2005-02-16) ESA's call for Gaia data reduction participation

(2005-02-14) Theoretical study completed

(2004-11-17) Introductory presentations from the Nov. 10, 2004 national meeting (Gaia-Koordinations-Treffen)

(2004-11-15) Four Paris conference papers completed

(2004-10-18) Gaia First Look study

(2004-09-13) Reference Systems, Conventions and Notations for Gaia

Astrometric observations of the Gaia satellite

New director of ARI

Gaia: The Galactic Census Project

Gaia First Look study

Another new team member

New team member

The announcement of the conference The Three Dimensional Universe with Gaia in Paris in October 2004 is now on the web

Astronomical Colloquium: "Gaia, The Galactic Census Project":

Heidelberg University lecture series on Gaia starting April 2004

German and English versions of a powerpoint presentation giving a brief overview of the Gaia project now available

Start of ''Science First Look'' study

Astronomical Colloquium "Gaia: The Galactic Census Project"

New public picture and graphics gallery

Two open positions for Gaia at ARI

ARI turning to Gaia after the demise of DIVA

(2007-12-17) SRR successfully completed:
The replies and suggested actions by DPAC on the SRR RIDs (see previous item for explanations) were all considered acceptable by the review panel. The panel has recommended that the review be declared successful by ESA. The panel has presented many conclusions and recommendations, but the general conclusions were all very positive for DPAC.
(2007-11-23) SRR discrepancy items treated:
ESA's review panel for the ongoing System Requirements Review (SRR) on the Gaia data reduction consortium (DPAC) has raised about 150 so-called Review Discrepancy Items (RIDs), of which 22 were related to the "Core Processing" unit of DPAC which is managed by U. Bastian of ARI. Formal replies were submitted to the panel today. They will be discussed at the SRR Colocation at Darmstadt on Nov 28/29.
(2007-11-22) Ecliptic poles observations, north and south:
Today we learned that our application for a few hours of observing time at the 4-meter Canadian French Hawaii Telescope, using the MEGACAM imager to observe the northern ecliptic-pole field was successful.
At the same time we were informed that the recent observing run at the ESO/MPIA 2.2-meter telescope on La Silla, using the WFI (wide-field imager) to image the southern ecliptic-pole field was largely successful; a small part of the planned imaging is still pending due to bad weather, but there is a chance to complete it later during this season.
The data from both observing programs will be used to produce multi-band photometry and astrometry for the preparation of the ecliptic-poles catalogue, needed for the initial calibration and verification of the Gaia payload and on-board software, as well as for the monitoring of the instrument during the scientific mission.
(2007-11-20) First delivery of a Detailed First Look Monitor:
Just a few days after the ring solution, the first official version of the Detailed First Look Monitor software (intended to make a daily in-depth check into the payload health and data quality during the Gaia mission) was delivered to ESAC. This completes the suite of planned software deliveries for 2007 well in time. The astronomical concepts for the Monitor were developed mainly by Michael Biermann and Stefan Jordan, the present Java implementation was designed and implemented mainly by Wolfgang Loeffler.
(2007-11-15) First delivery of a "ring solution" software:
The first official version of the "ring solution" software (intended to perform a daily high-precision astrometric adjustment and calibration of one day each of Gaia measurements from 2012 to 2017) was delivered to ESAC (Villafranca, Spain) for integration into the gradually forming Gaia Science Operations Center. This marks an important milestone in the Gaia software development at ARI. The software is accompanied by an extensive set of documentation and a test harness. The ring solution method was invented by Hans Bernstein, developed with Sonja Hirte, and coined into the present pre-operational Java software by Dirk Dorsch.
(2007-11-09) AGIS meeting at ARI:
A meeting on the Astrometric Global Iterative Solution (AGIS), the core of the astrometric data processing of Gaia, was conducted at ARI. Thirteen scientists from five European institutes met for two days. The meeting discussed the current results on the precision and the convergence behaviour of AGIS, the status of the software development, the detailed planning for the next two semesters, the connection between astrometry and orbit determination, as well as the treatment of the expected CCD radiation damage. The AGIS workpackage is developing very well and according to expectations.
(2007-10-31) SRR documents submitted:
The ongoing System Requirements Review (SRR, conducted on the Gaia data reduction consortium DPAC by ESA) reached a first milestone, the delivery ot the document package to the review panel. Exactly 100 heavy documents (46 formal review documents and 54 so-called supporting documents) will now be scrutinized by the international panel. Eighteen of these documents fall under the responsibility of the "Core Processing" unit of DPAC which is managed by U. Bastian of ARI. The entire review will be completed immediately before Christmas.
(2007-09-17) Conference "The Milky Way and the Local Group - now and in the Gaia era":
A scientific conference on Gaia-related Galactic research, and on the impact which Gaia will make on this research field, will be held at the Unviersity of Heidelberg from 31 August to 4 September 2009. This conference is being organised by Prof. Eva Grebel and Dr. Ulrich Bastian of the Astronomisches Rechen-Institut, part of the ZAH, Center for Astronomy of the University of Heidelberg. Further details will be made available at a later date. (Text copied from the Gaia homepage; specific planning will start in spring 2008, when also a more formal and more detailed first announcement will be issued)
(2007-09-14) WFI observing time granted:
Our application for one night of observing time at the ESO/MPIA 2.2m telescope at La Silla, using the WFI (wide-field imager) to observe the southern ecliptic-pole field was successful. The data will be used to produce multi-band photometry and astrometry for the preparation of the ecliptic-poles catalogue, needed for the initial calibration and verification of the Gaia payload and on-board software, as well as for the monitoring of the instrument during the scientific mission.
(2007-09-06) IDT/FL coordination meeting at Barcelona:
The intimately connected Gaia working packages IDT (Initial Data Treatment, centered on the University of Barcelona) and FL (First Look, centered on the ARI) had a two-day meeting to coordinate the logical interfaces, data interfaces, development schedules and the distribution of work. Six countries were represented with 23 scientists and software engineers from nine institutes. The most significant outcome of the meeting was the decision that countering the effects of the expected CCD radiation damage (caused by cosmic rays from the sun) must largely be done within IDT.
(2007-08-27) "ELSA" post-doc starting up at ARI:
The EU Marie Curie Research and Training Network "ELSA" (European Leaderhip in Space Astrometry) has created a two-year post-doc position for the Gaia group at ARI. Alex Bombrun, a young mathematician of Nice (France) who got his PhD in applied mathematics (control theory) at Paris this year, was selected to fill the post and to help investigate a possible direct global astrometric solution for Gaia (see previous news item). He will start up on Sep. 1.
(2007-08-22) Meeting on the "Direct Global Solution":
A first small meeting on Hans Bernstein's ideas for a direct - i.e. non-iterational - way to solve the overall Gaia astrometric adjustment problem was held on Aug. 20-21 at Lund Observatory. Some potential mathematical problems were unearthed in the present concept, and ways forward to confirm or disprove these worries were discussed, as well as possible ways to circumvent the problems. The next six months should tell whether the present ideas are viable.
Addendum, six months later: The mathematical problems turned out to be such that the 2007 concept had to be dropped entirely. See also the "current topic" of 2008-02-08.
(2007-08-01) Detailed First Look Monitor demonstration:
For the first time the Detailed First Look Monitor software (intended to condense pre-processed Gaia teleletry data into diagnostic quantities capable of assessing the payload health and science data quality) was faced with data from a simulated non-nominal Gaia. It nicely recovered sudden jumps in Gaia's "basic angle" and sinusoidal time variations of the telescope's focal length that had been hidden into the simulated data. Such effects would be deleterious for the "real" Gaia's astrometric performance. Their absence must therefore permanently be checked during the mission (2012 to 2017).

(2007-07-16) System Requirements Review on data reduction approaching:
The Gaia Data Processing and Analysis Consortium (DPAC) is heading towards its second major review (after the one leading to the approval of the consortium by ESA earlier this year): The System Requirements Review (SRR) is intended to verify that the scientific and technical requirements on the softwares and data to be produced by the DPAC have been properly analyzed and understood, and that appropriate software develoment plans and procedures have been drafted. The SRR will probably take place towards the end of the year. Production of the necessary documents has started throughout the consortium.
(2007-07-01) One departure, one addition to the Gaia group at ARI:
After her recent graduation as computer scientist, Nana Bach accepted a position as software developer in the Gaia group at ESAC, Villafranca. During the last two years she worked as student programmer for the Detailed First Look. - Astronomer Martin Altmann started up as successor of Bjoern Voss to take care of the ecliptic-poles catalogue (for initial calibration and verification after launch) and the ground-based optical tracking of the Gaia spacecraft (for precise orbit determination throughout the mission).
(2007-06-29) Gaia's Preliminary Design Review completed:
The Gaia project has taken an important step towards its late-2011 launch date. ESA's review board has released its report on the industrial Prelimary Design Review (PDR). The review was considered largely successful, with a number of important issues to be resolved by "work plans" till the end of the year.
(2007-06-07) Ring solution software reviewed at ESAC:
The Java software for the Ring Solution was reviewed at a dedicated meeting with the Data Processing Centre for CU3 (i.e. ESAC, Villafranca, Spain). The status of both the software and its documentation were well received. The big next step, viz. the change to the current Gaia-3 spacecraft and instrument configuration, was discussed and planned during the meeting. - In addition to the ring solution, the general status of the First-Look planning and documentation was informally reviewed, with a very favourable outcome in general, and a lot of actions assigned in the details.
(2007-06-06) Gaia's star names:
A proposal for the assignment and usage of source identifiers ("star names" and "asteroid numbers" throughout the Gaia data reduction consortium (DPAC) was elaborated. After appropriate discussion and iteration it will be formally approved by the DPAC Executive. The draft can be found here. The topic of this proposal is very important for the whole of the data processing because each and every of the many interleaved data reduction softwares must at any time be sure to know precisely to which celestial source (star, asteroid, galaxy, ...) a given piece of data belongs. No pre-existing naming scheme can be used for Gaia. First, there is no similarly complete sky survey as the future Gaia one. This means that many sources will be found and identified for the first time during the Gaia data processing. Secondly, the naming scheme must be such as to assist efficient data access for the data reduction softwares.
(2007-05-31) Results from the Ring Solution:
A technical note describing both technical and scientific results of the extended test and verification campaign for the Ring Solution software (the Fortran prototype, see current topics of 2007-02-20 and 2006-12-07) was issued. The results demonstrate the advantages of a direct solution over iterative ones, and they motivate some of the stringent requirements concerning the telemetry delivery schedule which were put forward to the Gaia project and Industry by the First Look group. The document can be found here (130 MB).
(2007-05-31) Bjoern Voss leaves the Gaia group at ARI:
The Planetarium at Muenster (Westfalen) offered him a permanent position as staff scientist. We wish all the best for his future in public astronomy.
(2007-05-30) Gaia's Preliminary Design Review (PDR) under way:
The industrial development of Gaia is taking another major milestone, the PDR. Parts of Astrium's huge documentation package were given to the Gaia Science Team for review and comments. A total of 60 RIDs (Review Item Discrepancy reports) on the payload data handling system, the video processing units, the attitude control system and structural vibrations were submitted into the PDR process from Heidelberg.
(2007-03-01) Second software engineer arrives:
On March 1 Wolfgang Loeffler started up as the second software engineer in the Gaia group at ARI. He will mainly work on the development of the First Look Monitor and First Look Evaluator software systems. Originally trained as astrophysicist, he has worked in the software industry ever since his PhD.
(2007-02-20) Ring solution successfully ported to Java:
The Fortran prototype of the `ring solution' method for the First-Look subtask called `one-day astrometric solution' was successfully translated into Java by Dirk Dorsch. Within very short time he produced a Java software adapted to the target Gaia processing environment. The differences in the numerical results between the Fortran and the Java versions are below 0.01 micro-arcsec. Close inspection has shown that they can be plausibly attributed to just arithmetic round-off effects, plus a trivial (and irrelevant) rotation of the coordinate system.
(2007-02-05) 2nd CU3 plenary meeting forthcoming:
On March 15/16 the 2nd plenary meeting of Coordination Unit 3 ("Core Processing") of the Gaia Data Processing Consortium DPAC will take place at Dresden. Registration (see here) and collection of agenda topics (see here) are open meanwhile.
(2007-01-28) Open positions in Gaia-related project:
Nine PhD and five post-doc positions are available in the EU-funded Marie-Curie Research and Training Network "ELSA" (European Leadership in Space Astrometry). One of the post-doc positions is associated to the Gaia group at ARI. For details see the ELSA web pages: http://www.astro.lu.se/ELSA/index.html
(2007-01-08) Two new team members:
On Dec 15 Dirk Dorsch started up as Java software developer. His first task will be to transfer the `ring solution' prototype software from Fortran to Java. - On Jan 2 astronomer Björn Voss joined the Gaia group. He will mainly work on two projects: the pilot study for the ground-based optical tracking of the Gaia spacecraft (for precise orbit determination), and the special ecliptic-poles star catalogue (for Gaia's initial calibration).
(2006-12-13) German version of Gaia overview presentation:
A German version of the overview presentation on the Gaia mission was produced by W. Hofmann. It can be found here a PDF file or a Powerpoint file, and also via the Gaia home page under the item "presentation material".
(2006-12-07) Ring solution results:
The results of the test runs with the ring solution software (see current topic of 2006-09-08) were presented by Sonja Hirte. The presentation can be found here. A more formal document will be produced in due time.
(2006-12-05) Response to ESA's Announcement of Opportunity for the Gaia scientific data reduction:
It was completed and submitted today. It is a 650+ page document, produced collectively by about two dozen Gaia activists. It will become publicly available after the formal deadline for submission (Dec. 11). In addition to its primary, formal role it will serve as a very useful handbook, especially for newcomers to the Gaia data reduction consortium, of which there will be quite a number over the next one or two years.
(2006-11-19) Detailed First Look Monitor software reviewed at ESAC:
A Detailed First Look Monitor (DFLM) prototype software was reviewed at a dedicated meeting at the Data Processing Centre for CU3 (ESAC, Villafranca, Spain). The Java software was presented by Michael Biermann and two students, and was well received. Major changes for the cycle-2 version of the software, mostly with respect to I/O utilising the data train concept of AGIS, were agreed upon.
(2006-11-09) Call for Data Processing Consortium from ESA:
Today, ESA issued the Announcement of Opportunity for the Gaia scientific data reduction. This is the call to the European science community to form a Gaia Data Processing and Analysis Consortium. In actual fact this consortium has been forming since April 2005, and its subdivisions and organs were formally created between Dec 2005 and May 2006, so that the relevant science community can respond with a massive and sound proposal to ESA before the deadline of 11 Dec. ESA will then scrutinize the proposal and is expected to accept it early next year.
(2006-11-03) Image reconstruction from Gaia raw data:
While Gaia primarily wants to determine astrometric, photometric and physical parameters of point-like sources (single stars) down to 20th magnitude, there is also a project to map the immediate surroundings (just a few arcsec) of each of the 1 billion Gaia stars at 0.15 arcsec resolution down to about 23rd magnitude. David Mary (ARI) and Hans Lindstroem have completed a study on the feasibility and performance of this so-called image reconstruction process, using a fairly simple method to start with.
(2006-11-02) First realistic Astrometric Global Iterative Solution achieved:
The Astrometric Global Iterative Solution (AGIS) is the very core of the Gaia data reduction. A highly satisfactory result was recently achieved in the very first attempt at an AGIS solution under realistic conditions, i.e. starting from a conservative pre-launch knowledge of the sky, and very conservative initial errors in the attitude and calibration parameters. For detatils see here
(2006-10-19) Data prioritization scheme accepted by Astrium for on-board usage:
A telemetry prioritization scheme has been developed under the leadership of Michael Biermann which on the one hand defines the most valuable data from the science point of view and on the other hand separates the measurements required by the Detailed First Look (to judge the instrument health and the scientific data quality on a daily basis). The chosen telemetry partitioning ensures the availability of the Detailed First Look data even at times when Milky Way scans lead to exhaustion of the telemetry capacity. The proposed prioritization scheme was adopted by Astrium and will be implemented on board Gaia.
(2006-10-10) "Ecliptic-poles scanning law":
At the 18th meeting of the Gaia Science Team, U. Bastian (ARI) presented a proposal to add an "Ecliptic-poles scanning law" to the functionality of Gaia's attitude control system. This would significantly would help initial in-orbit verification and calibration of Gaia, especially in conjunction with a special ecliptic-poles star catalogue, to be prepared on ground before the launch of Gaia. The proposal was well received, and ARI will set out to coordinate the production of the ecliptic-poles star catalogue.
(2006-09-16) Extended geometric calibration model for Gaia:
On Sep 15/16 H. Lenhardt (ARI) visited ESAC (Villafranca, Spain) to integrate a piece of Java software into the Gaia core data processing system. Prior prototypes of the Gaia calibration model were too simple to represent a real Gaia. With the new module the calibration model is extended e.g. to consistently represent optical distortion, changes in effective focal length of the telescope(s), and small rotations of the CCDs due to imperfect alignment during glueing of the detectors onto the focal-plane assembly. For more details see here.
(2006-09-08) One-day Astrometric Solution - the Ring Solution Method:
A core part of the Gaia First-Look system being developed at ARI is the so-called one-day Astrometric Solution (ODAS). Two methods have been developed to perform this task: The one-day iterative solution (ODIS) and the Ring Solution method (RSM). While the former was developed in 2004 to quickly demonstrate the basic feasibility of an ODAS in principle, the latter is the mathematically more elegant and efficient method to be used in the actual Gaia operations phase. S. Hirte and H. Bernstein have recently verified the last functional blocks to the existing Fortran prototype software for this method. Today they completed the documentation for this software version. The next steps will be to re-run and document all the test runs, and then to transform it into a Java code to run within the Gaia data processing system. The former task will run till the end of this year, contributions to the latter task will be one of the first major duties of the future Gaia software engineer at ARI (see previous "current topic").
(2006-08-28) Open positions in the Gaia group at ARI:
The Gaia group at ARI offers open positions for an astronomer and a software engineer/software developer. Deadline for applications is Oct. 31.

(2006-06-02) Concept for quick data delivery produced:
The First-Look group at ARI/ZAH has produced a concept for the on-board data storage organisation which allows quick delivery from satellite to ground of a specific subset of the Gaia observations. This subset is defined such that it enables a quick in-depth health and performance assessment of all important aspects of the Gaia science measurements. The ultimate goal is to make sure that we always get the best possible data out of Gaia, by quickly (within days) identifying opportunities for data optimization and/or to trigger remedies for upcoming problems during Gaia's science mission.

(2006-05-20) Gaia Data Processing and Analysis Consortium (DPAC) formally created:
At its fourth and presumably last meeting the Gaia DACC ("Data Analysis Coordination Committee", a temporary body set up by the Gaia Science Team to organize the start-up of a Gaia data reduction consortium) formally created the DPAC. It consists of the eight already existing "Coordination Units" (CUs), a number of data processing centres and an executive (the latter being abbreviated "DPACE"). The DPACE in turn consists of the eight CU managers (appointed in the course of this spring by each CU independently), one data processing centre representative, a chairman and a co-chairman. For the latter two positions the DACC has proposed candidates to be confirmed (via non-objection) by the CU members, after which the consortium will formally start operating.
(2006-05-19) Schedule for ESA's Announcement of Opportunity for the Gaia data reduction:
At the DACC-4 meeting (see next item) the current Gaia project scientist announced that the Announcement of Opportunity for the Gaia data reduction will be issued at the end of June, i.e. about one month later than originally planned. The response, i.e. a data reduction consortium proposal to ESA, will be due by early October.

(2006-05-17) Gaia Science Management Plan essentially approved:
ESA's Science Program Committee (SPC) on its meeting of May 15/16 has essentially approved the Gaia Science Management Plan, with only minor modifications to be agreed on during the next weeks.

(2006-05-02) Astrometric Global Iterative Solution "test bed" running at ARI:
A "test bed" version of the Gaia GIS (Global Iterative Solution) has been installed at ARI, in order to facilitate the development of software modules to be incorporated into the "real" software version which is built up at ESAC Villafranca (Spain). The first such module to be produced is a more realistic and complete geometric calibration model for Gaia's astrometric instrument.
(2006-04-11) Gaia Science Management Plan:
The preparation of ESA's Announcement of Opportunity (AO) for the Gaia data reduction has entered the formal procedures. ESA's Astronomy Working Group (AWG) last week accepted the draft Gaia Science Management Plan, with only minor modifications requested. The next steps will be its approval by the Science Program Committee (SPC), and then the AO.

(2006-02-28) Gaia CU3 meeting:
The meeting was quite successful. The Gaia data processing Coordination Unit 3, "Core Processing", was formally created. The meeting agreed on a management structure for CU3 and largely decided on the division of tasks among the contributing groups. The provisional CU3 manager, U. Bastian, and the two deputy managers, J. Torra and M. Lattanzi were confirmed by the assembly. Thirty-six out of the 49 CU3 members attended the meeting, plus a number of guests from other CUs. All presentations and the decisions of the meeting can be found on the meeting webpage.

(2006-02-13) New team member:
David Mary, french astronomer and signal processing expert on Feb 13 joined the Gaia group at ARI for ten months. He will work on the interpretation and usage of Gaia's dispersed images for photometry purposes, and on Gaia's observations of very bright stars.

(2006-02-09) Gaia has the final "go" !
Quoting today's email from the ESA's Gaia Project Scientist, Michael Perryman, to the Gaia Science team: "Gaia, and the requested Cost at Completion, was unanimously approved at today's SPC. We now proceed to Phase B2, with the kick-off meeting with EADS-Astrium next week."
The SPC is ESA's highest, and in the approval procedure last, science advisory body. Its decision gives the final "go" to the project. The requested Cost at Completion is 557 MEuro, to be spent till the planned end of the project, i.e. about 2019. Astrium's new technical design of the Gaia spacecraft and payload will become public within the next two or three weeks.

(2006-01-27) ARI's "Gaia professor" coming:
This week saw the presentations and the interviews of the candidates for the newly created "Gaia professorship" at ARI. We heard four excellent talks. The current schedule target is that the University of Heidelberg should be able to formally offer the position to one of the candidates by May or June this year. The successful candidate is supposed to do academic teaching and Gaia-related research, and to head the existing Gaia team at ARI. This forthcoming new position will strengthen the profile and visibility of the German Gaia contribution.

(2006-01-24) Good prospects for Gaia:
The prospects for Gaia for the forthcoming final ESA decisions on the project implementation look very good. The SPC (Science Program Committee) on its next meeting (Feb 8) is supposed to discuss the financial and technical aspects of the envisaged "big four" missions Gaia, Bepi Colombo, Solar Orbiter and Lisa. There is a certain possibility that one of them may be delayed significantly, or even deleted. For Gaia there are two very favourable preludes to this:
1) The 19 January SSAC recommendation towards SPC reads: "... On the GAIA mission, the SSAC felt that its scientific case was shown to be compelling and actually so broad in scope as to serve the interest of a community much wider than the astronomy one, including, as it does, science related to solar system as well as fundamental physics topics. The SSAC congratulates the Executive on a highly professional presentation and programme management and recommends that, following the Invitation to Tender (ITT) responses and their evaluation by the Executive, the GAIA mission proceed with the utmost expediency so as to meet a 2011 launch date. ..."
2) The ESA executive paper towards SPC in its conclusion recommends that the SPC approve the proposed financial envelope for the Gaia mission, and that this SPC approval will confirm the Gaia mission to continue into the Implementation Phase for a launch in late 2011.
Thus we may look forward to the forthcoming decisions. Let us keep our fingers crossed that on Feb 8 we will have the final "go" for Gaia.

(2006-01-13) Gaia prime contractor recommendation:
Astrium Friedrichshafen and DLR have confirmed rumours that ESA's technical evaluation board for Gaia has recommended to select the Astrium design and proposal for the procurement of Gaia. There were two proposals in the competition. The board's recommendation is still subject to approval by ESA's Industrial Policy Committee (IPC) on Feb 1/2. The technical details of the Astrium design are still under embargo by ESA, for legal reasons.

(2005-12-09) Gaia CU3 meeting:
Provisional agenda available. Please register soon, see meeting webpage .

(2005-11-04): Gaia CU3 meeting:
The second announcement of the first meeting of the DPAC Coordination Unit 3, "Core Processing", scheduled for Feb. 23/24, 2006 at Heidelberg, was issued yesterday. It contains registration and hotel info, and the detailed time and location of the meeting. The scientific scope and a draft agenda will be added within the next two to three weeks.

(2005-10-26) Several meetings scheduled:
The build-up of the Gaia Data Processing and Analysis Consortium (DPAC) gains momentum. The most obvious sign is the increasing number of meetings that are being scheduled (see also the "calendar of meetings" section on the Gaia home page). Among the meetings that directly concern the Gaia crew at ARI are the Simulation Working Group at Paris (Nov. 2-4), the meeting of the provisional DPAC executive (DACC) at Nice (Jan. 19/20), the first meeting of the DPAC Coordination Unit 3, "Core Processing" at Heidelberg (Feb. 23/24) and, on a smaller scale, visits of ARI's Hans Lindstroem to ESAC Villafranca (Nov. 3/4), of ESAC's John Hoar to ARI (Dec. 6/7), of ARI's Michael Biermann to ESOC Darmstadt (mid November), of Jean-Michel Désert (Paris) to ARI (late November), and of Floor van Leeuwen (Cambridge), also to ARI (Jan 17/18).

(2005-10-18) New team member:
Hans Lindstroem, a software systems architect from Copenhagen, on Oct 18 joined the Gaia group at ARI for nine months. He will support the ARI astronomers on the design and development of data reduction software - in the process teaching us the modern ways of software production. His arrival nicely fits with the ongoing transition of the Gaia data reduction efforts from the previous study and prototyping phase (1998-2005) towards the phase of actually designing and building an operational data processing system (2006-2011).

(2005-09-15) Resumption of the "current topics" column:
Our "current topics" column was much neglected during the last five months. This will now be repaired. Over the next few days we will enter a number of "current topics", working our way backwards from this very day, down to the last entry before the gap (2005-04-19). The fill-in entries will appear ordered according to their logical date, not according to their creation date.

(2005-09-14) Ground Segment / First Look coordination meeting:
A first meeting between the Gaia Ground Segment (in particular the newly appointed Gaia Ground Segment Manager Claudio Sollazzo), the Gaia Project Team (lead by Project Manager Rudi Schmidt) and ARI's First Look team took place today at ESOC, Darmstadt. Topics included: the requirements on quick monitoring of payload health and performance during the mission, possible contributions from the First Look team, the present status of the First Look work at ARI, the requirements on the orbit determination precision, and the initial geometric calibration of Gaia after launch.

(2005-09-12) Different method yields identical results:
Our second method for the solution of the "first-look preprocessing" problem, the so-called ring solution method (RSM) has for the first time produced valid results. A comparison with the older results of our alternative method (the so-called one-day iterative solution or ODIS, see the dedicated ODIS page) showed practically perfect agreement. This pleasant finding confirms the success of both methods at the same time. More information will be given on the ODIS page after September 27. The RSM will replace the ODIS as baseline emthod as soon as the RSM software is completed, because it is the mathematically more elegant and flexible solution.

(2005-08-02) First Look concept study completed:
A broad concept study on the requirements, methods and procedures for a quick in-depth assessment of payload health and microarcsec performance verification was completed. The final reports on the study results were submitted to ESA during June and July. The study achieved all its essential goals. One of the scientific results was presented to a larger audience as a "Gaia Picture of the week", see here. The complete report on these results can be found here.

(2005-08-01) Gaia enters the industrial implementation phase:
In July the European Space Agency released the invitation to bid for the construction of Gaia to the European space industry. This marks the formal start of Gaia's construction phase. Proposals from industry are due in October, the selected industrial prime contractor will be announced in February 2006. The target launch date is late 2011.

(2005-06-17) Leading positions for Heidelberg astronomers:
Two Heidelberg astronomers were appointed leading positions within the forming Gaia data reduction consortium. At the first meeting of this consortium's provisional executive body (called DACC, Data Analysis Consortium Committee) Coryn Bailer-Jones of the Max-Planck-Institut fuer Astronomie was elected vice-chairman of the DACC. Ulrich Bastian of the Astronomisches Rechen-Institut was appointed `manager' of one of the six top-level subdivisions of the consortium, viz. Coordination Unit 3, "Core Processing".

(2005-04-22) Gaia data reduction consortium under construction:
The Gaia Science Team at its recent meeting launched the construction of the Gaia data reduction consortium. This consortium of European scientists will be responsible to organize and execute the transformation of Gaia's raw data into the most precise and comprehensive star catalogue in the history of astronomy. A provisional organizing committee will, from now till mid 2006 pull together a three-digit number of (predominantly European) astronomers and computing experts to perform that task. This is done in preparation of ESA's `Announcement of Opportunity' for the Gaia data reduction, currently expected to be issued around April 2006.

(2005-11-02) RVS / FL meeting on Dec. 2:
Several colleagues from the Gaia Radial-Velocity Spectrometer (RVS) group at Institut d'Astrophysique (Paris) will visit ARI to discuss for a full day about the needs and possible concepts for the RVS First Look.

(2005-04-19) A movie from the Gaia First Look study:
A document briefly describing the first realistic numerical experiment with the ODIS method for the `First Look Preprocessing' task, and a movie showing its (still unsatisfactory) convergence behaviour can be found here. -

(2005-04-15) Gaia data reduction - `Letters of Intent' to ESA:
A total of 177 letters of intent to participate in the Gaia data reduction were submitted to ESA by science institutes and individuals from all over Europe. Among these there were 21 from Germany, from eight different institutes. The letters are under scrutiny by ESA's Gaia project team and by the Gaia Science Team. They will be used to draw lessons for the formation and structure of the Gaia data reduction consortium, to improve the coordination between various groups intending to work on similar subjects, and to avoid unnecessary duplication of work. The originators of the letters of intent will soon get a first reply from the Gaia project team.

(2005-02-16) ESA's call for Gaia data reduction participation:
On January 15, 2005 ESA issued a formal call for Letters of Intent to participate in the Gaia data processing. Details can be found via the Gaia home page , or directly on the call page. German astronomers have agreed to undertake a national coordination effort before submitting Letters to ESA. Details can be asked from U. Bastian . The Letters are due to ESA by March 20.

(2005-02-14) Theoretical study completed:
A theoretical study on the astrometric meaning and interpretation of high-precision CCD data recorded in time delay integration mode was accepted for publication in the journal Astronomy and Astrophysics. The paper can be found here.

(2004-11-17) Introductory presentations from the Nov. 10, 2004 national meeting (Gaia-Koordinations-Treffen):
"Overview of the Gaia project and its organization" (C. Bailer-Jones)
"The present status and schedule of Gaia" (U. Bastian)

(2004-11-15) Four Paris conference papers completed: The four papers of ARI for the proceedings of the conference "The Three-dimensional Universe with Gaia", Paris, Oct 4-7, 2004, have been completed and submitted to the editors. Preprints can be found on our "Selected documents and papers" page. - (2004-11-15)

(2004-10-18) Gaia First Look study:
In late September 2004 the One-Day Iterative Solution (ODIS) method of Gaia's astrometric First Look Preprocessing was brought to convergence for the first time. Programming of the Ring Solution, the alternative way to solve the problem, is still going on. For more details see here. - (2004-10-18)

(2004-09-13) Reference Systems, Conventions and Notations for GAIA:
A new pdf version of this document has been completed (version 4.0, 2004-09-09). - (2004-09-13)

Astrometric observations of the Gaia satellite:
Following a two-year old suggestion by U. Bastian of ARI, orbit tracking expert M. Hechler of ESOC has investigated the usefulness of ground-based astrometric observations of the Gaia satellite for high-precision orbit determination. In a recent report he finds that presently this is the only way to satisfy the tremendous requirement of 0.7 mm/s accuracy (in all three space dimensions!) for Gaia's barycentric velocity vector.

New director of ARI:
Joachim Wambsganss started up work and directorship at ARI on Aug. 1, while his formal advent to office will probably be around Christmas. His plans include support and development of ARI's involvement with Gaia.

"GAIA: The Galactic Census Project." Talk given by Francois Mignard, of Nice (France), at Astronomisches Kolloquium Heidelberg, May 18, 2004. His presentation material is available as pdf file and Powerpoint Powerpoint file.

Gaia First Look study:
The current status of the Gaia First Look study is summarized in a presentation to the joint meeting of the Simulation, On-board Detection and Calibration Working Groups (Torino, July 2004).

Another new team member:
Sebastien Picaud joined the Gaia group at ARI on April 1. He is planning to do galactic modelling in the framework of the Gaia science preparations. He will be ARI's guest till end of September. More info about him can be found on his personal homepage .

New team member:
Stefan Jordan will join the Gaia group at ARI as of April 1, 2004. He will mainly contribute to the Gaia First Look study. More about Stefan Jordan can be found on his personal homepage . A brief explanation of the Gaia First Look can be found in the archive of current topics.

The announcement of the conference The Three Dimensional Universe with Gaia in Paris in October 2004 is now on the web, see here

Astronomical Colloquium: "GAIA, The Galactic Census Project" by F. Mignard, Nice (France). Tuesday, 18 May, 17:15, Hoersaal of the MPI fuer Astronomie (Heidelberg-Koenigstuhl).

Heidelberg University lecture series on GAIA starting April 2004.
Details in PS and Html

German and English versions of a powerpoint presentation
giving a brief overview of the Gaia project
now available here (German) and here (English)

Start of ''Science First Look'' study (details)

Astronomical Colloquium "GAIA: The Galactic Census Project" by L. Lindegren, Lund (Sweden),
postponed to summer semester , Auditorium of Kirchhoff-Institut, Heidelberg, Im Neuenheimer Feld 227

New public picture and graphics gallery. Click here

- 6-month position announcement in PS and plain text
- 12-month position announcement in PS and plain text

ARI turning to GAIA after the demise of DIVA (details)

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