1. MAG->RCV 2007/09/26 Edinburgh LOFAR Status Internal review of the project (April-July 2007): Main conclusions: R&D developments in good shape (CS1 results) Development costs in line with original estimates Original 77-station LOFAR relied on significant matching from original international partners (e.g. ATNF, MIT, NRL) –77 station unrealistic in short-term… De-scope process initiated - August 2007 Need for a re-scoped LOFAR presented to NL and international (DE & UK) commiunities Prof. Ralph Wijers (chairman of NL-ARC) together with the support of the LOFAR project directorate, asked to report to the ASTRON board on: – the extent of the necessary de-scope – the optimal configuration based on (i) the most pessimistic and (ii) a more optimistic scenario –3 meetings, including an open workshop (17 September 2007)

2. MAG->RCV 2007/09/26 Edinburgh Wijers’ draft report Wijers’ draft report presented to the ASTRON board (21 September 2007): Original LOFAR: 96 LBA & 96 HBA HBA ~ 16 m^2 32 core stations, 45 outer stations; 77 stations in total Re-scoped LOFAR: –Core: 96 (48) LBA & 2 x 24 HBA –Outer: 96 (48) LBA + 48 HBA –25m^2 HBA N.B. Stations smaller but Field of View expanded by x4 No. of stations reduced: –Minimal (most pessimistic) configuration 36 (18+18) stations –Most optimistic configuration 50 (25+25) station Build long-baseline stations towards German border

3. MAG->RCV 2007/09/26 Edinburgh Wijers draft report (cont) Wijers’ draft report presented to the ASTRON board (21 September 2007): Original LOFAR: 96 LBA & 96 HBA HBA ~ 16 m^2 32 core stations, 45 outer stations; 77 stations in total Re-scoped LOFAR: –Core: 96 (48) LBA & 2 x 24 HBA –Outer: 96 (48) LBA + 48 HBA –HBA now 25m^2 N,B, Stations smaller but Field of View expanded by x ~ 4 No. of NL stations reduced: –Minimal (most pessimistic) configuration 36 (18+18) stations –Most optimistic configuration 50 (25+25) station Build long-baseline stations towards German border. International stations remain unchanged in size.

4. Constraints on rescope 1. Money: 25 MEUR phase 1 2. Rollout Schedule: before end 2009 done 3. Software = capabilities 4. Calibrateability 5. Expandability: (?)0-8 MEUR phase 2,..... 6. Eu-LOFAR 7. Operations: cost control 8. Other sciences (geo/agro/meteo/....)

5. LOFAR-ph1 Global 50%-50% core/outer split in NL, aim for 25+25 Keep European stations original 96+96 Make NL stations smaller: core: 96/48 LBA + 2x24 HBA outer: 96/48 LBA + 48 HBA 25 m 2 (4x4) HBA tiles Bias outer stations towards Germany (lopsided configuration)

6. LOFAR-ph1 rationale - I 50%-50% core/outer split, aim 25+25 uv-coverage has priority over raw collecting area, both core (EoR, RSM) and outer (resolution, SRV) need to be good  more smaller stations Below 25+25, good uv-coverage quickly gets harder

7. LOFAR-ph1 rationale - II Keep European stations 96+96 Fewer outer baselines: sensitivity very important for calibration Split-station needs higher data rate and use of larger FOV initially doubtful

8. LOFAR-ph1 rationale - III NL outer station: 96/48 LBA + 48 HBA HBA and RCUs are expensive, so reduction most helps more stations LBA are cheap, hard to add, so put all 96 and use LBL/LBH to connect all, but only 48 can be used. Select inner/outer 48 Select ‘minitile sum’ of 2 for better sensitivity NOTE: 48 has larger FOV!

9. LOFAR-ph1 rationale - IV NL core station: 96/48 LBA + 2x24 split HBA LBA same as outer HBA split in two fields at ends of 100m x 200m field Better uv-coverage in core 24-HBA substation has even larger FOV Price: 2 substation signals out, higher data rate

10. LOFAR-ph1 rationale - V Maintain long baselines and build lopsided towards Germany Important for resolution and depth (confusion limit) and connection to E-LOFAR Lopsided to East gives more weight to long baselines than symmetric distribution around core Price: more time to fill uv-plane

11. LOFAR-ph1 Rollout 20 stations, 13 core + 6 outer + 1 distant outer, by end 2008 Rest by end 2009, in logistically best order HBA subCDR and 20-station review should be planned to minimally delay rollout. Software rollout plan is urgent

12. MAG->RCV 2007/09/26 Edinburgh LOFAR organisation ASTRON is the largest partner, assumes the vast majority of risk, provides the expertise and man-power for the development, roll-out and commissioning of LOFAR. LOFAR Managing Director reports on a daily basis to ASTRON General Director. Radio Observatory ASTRON will be responsible for LOFAR operations. Radio Observatory ASTRON will be the international communities contact point for E-LOFAR.

13. MAG->RCV 2007/09/26 Edinburgh LOFAR Astronomical Exploitation ASTRON / Radio Observatory takes up long-term coordination of LOFAR astronomical exploitation Run as broad common-user observatory, while astronomical user groups focus on their particular science projects. Three-tier allocation of “observing time”: Current LOFAR KSPs given proper recognition: Highly valuable contributions, major undertakings New parties welcomed and encouraged, especially if: Contributing to development of (extended) LOFAR infrastructure Contributing to sustained LOFAR astronomical operations Substantial fraction open to worldwide community. This is vital: To foster the user community For the overall and long-term scientific success Services may be provided for non-astronomical applications, brokered through LOFAR foundation

14. MAG->RCV 2007/09/26 Edinburgh Evolving Observatory Structure Astronomical operation of LOFAR and the WSRT in a fully integrated Radio Observatory division Observatory Operations Room in Dwingeloo will be taken into use next month Observatory is interface between R&D and Astronomy (“customer”, “supplier” roles) Observatory contacts for all LOFAR system components New Science Support Group getting established Services may be provided for non-astronomical applications, brokered through LOFAR foundation

15. MAG->RCV 2007/09/26 Edinburgh Evolving Observatory Structure Minimum critical mass, structure, and composition to allow optimizing: Quality of operations Overall cost Budget now on firm footing Augmentation above minimum critical mass possible in a natural way International share of the operations/costs must be discussed Lessons must be learned for CS1 about best practice operational model Technically: maintenance, operational procedures, documentation Partnerships: RUG/RC, KSP-centres, E-LOFAR, multi-disciplinary aspects, outsourcing

16. MAG->RCV 2007/09/26 Edinburgh The latest commissioning results