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EVLA Status --

National Radio Astronomy Observatory. EVLA Status --. Jim Ulvestad, for Mark McKinnon, Rick Perley, and the EVLA Team. EVLA Project Overview. The Expanded Very Large Array is a major upgrade of the Very Large Array.

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EVLA Status --

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  1. National Radio Astronomy Observatory EVLA Status-- Jim Ulvestad, for Mark McKinnon, Rick Perley, and the EVLA Team

  2. EVLA Project Overview • The Expanded Very Large Array is a major upgrade of the Very Large Array. • The fundamental goal is to improve all the observational capabilities of the VLA -- except spatial resolution -- by at least an order of magnitude. • The Project began in 2001, and will be completed in 2012, on time, on spec, and on budget. • Limited ‘Shared Risk’ Observing will begin late in 2009. • Observing Capabilities will rapidly rise through 2010 – 2012.

  3. The Eight Cassegrain Frequency Bands Showing the performance and characteristics of the eight bands * Without the new wideband OMT + The current VLA receiver # Will improve after optics alignment and panel adjustments

  4. EVLA Feed System • All eight Cassegrain feeds are compact or linear taper corrugated horns with ring loaded mode converters. • Horns are large (7 l aperture) because the subreflector is small. 1 – 2GHz 2 – 4 4 - 8 8 - 12 18 - 27 40 – 50 12 - 18 26 - 40

  5. Antenna Conversions • All 28 VLA antennas are being converted to modern standards at the rate of 5 to 6 per year. • Conversion Activities: • Add new feed cone to vertex room • Add new HVAC, power, and cryogenics distribution systems • Add IF, samplers, DTS electronics • Antennas emerge with: • Interim 20cm, 6cm receivers • Old 3.6cm receivers, • Final 1.3cm, 7mm receivers • S, Ka, new X, Ku bands to be installed later • Conversion on track for completion in Q3 2010 • 18 EVLA antennas now back observing. • 19th and 20th antennas are undergoing conversion

  6. Receiver Outfitting Details • Final K (18 – 26.5 GHz), Q (40 – 50 GHz) bands installed on converted antennas. • Full frequency coverage, and full sensitivity available NOW on all converted antennas. • Interim L (1 – 2 GHz), C (4 – 8 GHz) bands are on all converted antennas. • Full tuning range accessible, but with compromised sensitivity and polarization outside traditional VLA frequency ranges. • new wideband OMT design now completed, retrofitting in progress. • Ka (26.5 – 40 GHz) band prototypes field tested – meet all requirements. Accelerated outfitting now underway. • Six antennas currently equipped.

  7. Full-Band Tuning & Sensitivity Availability

  8. EVLA Imaging of HI Absorption at 1082 and 1139 MHz • Observations made in daytime, in D-configuration. • About 25% of data flagged for RFI of some sort. • Used 15 ‘interim’ EVLA antennas. • Sensitivity will increase dramatically with new OMT. EVLA and VLA 1139 MHz EVLA only 1082 MHz 1413+135 1127-145

  9. Other Unique EVLA Projects now Scheduled • Users have noted the increased frequency access: • 32 proposals accepted for C-band frequencies outside the VLA 4.5 – 5.0 GHz window. • Galactic science proposals involve methanol, excited OH, and formaldehyde masers in star forming regions. • Extragalactic science involves H2O masers near z = 2. • 9 proposals accepted for expanded K-band coverage. • Science goals mostly involving high-redshift (z ~ 2 – 5) molecular emission from young galaxies. • With more frequencies opening up, the interest in observing in these new bands will increase. • Most significant new capability in 2009 will be availability of Ka-band (26.5 – 40 GHz)

  10. New EVLA Science: C-Band and K-Band Results • C-band: • Traditional band is 4.5-5 GHz • Transition band is 4.2-7.7 GHz • First EVLA-only science: OH masers • AU Gem & NML Cyg: Sjouwerman et al. ( 2007, ApJL 666, 101) • ON1: Fish (2008, ApJL 669, 8) • K-Band: • Traditional VLA K-band: 21.2 - 25.2 GHz • EVLA band: 18.0 - 26.5 GHz • First interferometric detection of SiS (1-0) at 18.154 GHz • IRC+10216 (CW Leo) • Claussen & Wooten W3OH OH 6.035 GHz IRC+01216 SiS (1-0) 18.154 GHz

  11. Software for Science Support Systems • Proposal submission tool (PST) • Used for all VLA and GBT proposals • Observation preparation tool (OPT) • Replacement for VLA JObserve • Development well underway • Tested by NRAO staff • Observation scheduling tool (OST) • Under development • Demonstrated to ALMA software group • Alpha release next summer • Archive access tool (AAT) • Will likely be common with ALMA’s • Standardized binary data format with ALMA • Developing standard for science data model now

  12. The EVLA’s WIDAR Correlator • Replace existing VLA correlator with new wideband correlator • Designed and developed by Canadian partner (HIA) • All 16 racks (8 baseline racks, 8 station racks) are installed and cabled, awaiting the boards. • Custom chips (12,000) received in April 2008 • On-the-sky tests of prototype began in July 2008 • First fringes on August 7 • 4-antenna (6 baseline) data in hand • Full production of boards to start in early 2009 (CDR in December 2008)

  13. 1.024 GHz-wide WIDAR fringes

  14. New Science in the WIDAR Era • When 10-antenna prototype tests are completed, (mid-late 2009?) we plan to move quickly to replace the existing VLA correlator. • This WIDAR setup should provide, for all EVLA antennas, two basic modes: • Two independent sub-bands of 128 MHz each, with full polarization, and 128 channels/correlation. • One sub-band, RR and LL polarizations, 128 MHz BW, 512 channels per correlation. • For both modes, the bandwidth can be divided by powers of two while keeping number of channels fixed. • We will remain in this state for some time to ensure reliability and stability. • When stable and reliable, the VLA correlator will be decommissioned. (Not sooner than late 2009).

  15. Early WIDAR Science • Most early science experiments with this initial WIDAR configuration will likely: • Utilize high frequency bands (K, Ka, Q) • Not utilize high spatial resolution • By doing this, we minimize data set size and computing processing impact, and maximize science opportunities. • Only EVLA antennas can be used with WIDAR – the unconverted VLA antennas will be temporarily decommissioned. • In Sept 2009, only 4-5 VLA antennas left.

  16. WIDAR Science, 2010 and Beyond • All WIDAR hardware components will be here by late 2009. • WIDAR observational capabilities will rapidly grow through 2010. • Growth path not determined – much will depend on early science opportunities. • Most likely path is to maximize bandwidth quickly. • More complicated and flexible modes to be added (much?) later. • Increased number of channels • Greatly increased frequency resolution • Flexible correlator resource allocation • Pulsar mode observing • Phased array mode observing

  17. Major Milestones • Test 4-station prototype correlator on the sky July – Oct. 2008 • Four antenna test and verification system • Not available for science • Testing of 10-station correlator: Oct ’08 – Sept. 09 • Full Correlator Installation Jan ’09 – Dec ’09 • VLA’s correlator turned off Sept. 2009 • New correlator capabilities will be much greater • About 4 VLA antennas will not be usable (temporarily) • Resident Shared Risk Observing Begins ~December 2009 • Last antenna retrofitted Sept. 2010 • Last receiver installed Sept. 2012

  18. Resident Shared Risk Observing (RSRO) • We are planning a ‘Resident Shared Risk Observing Program’, to begin in late 2009: • Experienced observers favored • Resident in Socorro for at least 2 – 3 months • Early access to EVLA data products • Proposals will be peer reviewed • Support is possible (but budgets are questionable) • Details of this program under development • Announcement early next year (?)

  19. NRAO Opportunities • We are beginning a series of workshops to develop users knowledge of and interest in the EVLA. • The first of a series of EVLA workshops, with the theme ‘The EVLA Vision: Galaxies Through Cosmic Time’, is being held in Socorro, December 16 – 18. • Positions available! • Jansky Postdocs, • Tenure-track scientist • Software Management (CASA). • Check the NRAO website.

  20. In Conclusion • After many years of hard work, new EVLA systems are coming on line at a rapid pace. • The WIDAR correlator is being assembled now, and undergoing testing. • Correlator capabilities well in excess of those currently available will come in late 2009. • Rapid expansion in capabilities – particularly in sensitivity and spectral surveying – will come through 2010. • More exotic and powerful capabilities will arrive over the next few years. • The EVLA will be, through the next one or two decades, what the VLA has been over the past two decades.

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