1. VLBA Sensitivity Upgrade Project Status Jon Romney NRAO, Socorro 7 th US VLBI Technical Coordination Meeting Haystack Observatory 2009 November 3–4

2. 2009 / 11 / 3-4 – jdr7th US VLBI Technical Coordination Meeting 2 Project Goal Expand the VLBA’s data-path bandwidth to 4 Gbps by 2011 Goal has been widely and frequently announced within the radio astronomy, astrometry, and geodesy communities. VLBA users are waiting to exploit it to enable a variety of compelling new science.

3. 2009 / 11 / 3-4 – jdr7th US VLBI Technical Coordination Meeting 3 Implementation Goal Corresponds to: 2 IFs @ 500 MHz BW @ 2-bit Nyquist samples [i.e., retaining VLBA’s original IF system.] New Elements RDBE sampler/filter unit. Mark 5C recording system. DiFX software correlator.

4. 2009 / 11 / 3-4 – jdr7th US VLBI Technical Coordination Meeting 4 Project Status DiFX Software Correlator Operational Comparisons with original VLBA correlator yielded excellent results. Exactly matched integrations show amplitude and phase agreeing far better than realistic expectations. Science use cases, analyzed by expert VLBA users, finding primarily limitations of data-analysis algorithms, not problems in correlator results. DiFX alone enables some new scientific techniques. High spectral resolution. Wide-field imaging. Special pulsar processing. Announced for correlation of all observations proposed Oct. 1. Observation trimester beginning mid-January. Planning to ramp up use beginning as soon as possible. But DiFX can’t really come into its own without wideband observations.

5. 2009 / 11 / 3-4 – jdr7th US VLBI Technical Coordination Meeting 5 Status, continued RDBE & Mark 5C Absolutely central to achieving 4-Gbps goal. Some initial efforts successfully behind us: ROACH final design, layout, exhaustive testing, beginning of production. Mark 5C concept design, development and production of 10 Gig E interface mezzanine board. But both efforts have encountered schedule slippages, sufficient to become serious concerns. Both NRAO &Haystack have major competing priorities: EVLA & MWA. Conduant also? To recover schedule, we need to consider alternative approaches, possibly including Additional personnel resources. (Matt Luce recently joined NRAO team, for FPGA development.) Simplified, less comprehensive design “at least initially”. We hope to revisit these points throughout this meeting!

6. 2009 / 11 / 3-4 – jdr7th US VLBI Technical Coordination Meeting 6 Thank You