VLA/VLBA INTEGRATION With appropriate outfitting, the VLA+NMA+VLBA could be one integrated instrument covering all resolutions from arcminutes to well under a milliarcsecond. Question for the community: How much of the outfitting of the VLBA antennas required to obtain this capability should be part of the EVLA Phase 2 project?

SOME INTEGRATION IS REQUIRED Use of LA and PT in NMA forces integration Those stations need EVLA systems This means that the required hardware designs will exist Their use forces integrated scheduling The boundary between EVLA and VLBA becomes fuzzy PT link already significantly impacts VLBA scheduling VLBA is seriously compromised without PT and LA No short spacings and only 8 antennas NMA is compromised without PT and LA

BENEFITS OF EVLA/VLBA INTEGRATION Continuous coverage of baselines 25m to 8600km Choose resolution based on science Provide wide uv range for quality imaging Many subarray combinations possible NMA adds the equivalent of 4 new VLA configurations: 100 and 300 km “arrays” when used with VLA 1000 and 3000 km “arrays” when used with VLBA Wide band EVLA correlator offers much improved sensitivity for high resolution observations Receiver upgrades open new regions of spectrum Leverages past investments in antennas, sites, and equipment Gives experience with SKA scale array

Resolution vs. Frequency

UV Coverage of VLBA+NMA “VLBA C Configuration” 1000 km scale UV Coverage of VLBA+NMA Blue: VLBA-VLBA Red: NMA-NMA and NMA-VLBA “VLBA B Configuration” 3000 km scale

SCIENCE ON VLBA+NMA Matched resolution at multiple frequencies to understand source physics Jet slowing regions in FRIs. Milliarcsecond resolution of thermal sources Identify ultra compact HII regions in nearby galaxies Scattered sources at L band - includes most galactic objects Includes pulsars and OH masers Jets from galactic compact objects like AGN but with fast evolution Stellar masers - where is the missing flux? Intermediate scale absorption studies (eg HI)

Matched Resolution Imaging Example: Free free absorption in 3C84 Effects of limited short baselines: Jet features almost completely resolved out at 43 GHz Southern extension resolved out above 5.0 GHz Same-resolution imaging limited to about factor of 4 in resolution on VLBA Note, this could be done on much weaker sources with EVLA bandwidths.

Multiscale Imaging Limitations Note huge resolution difference NMA partially fills missing resolutions VLBA-EVLA connection needed to fill well 0.1" Superluminal feature VLBA 1.7 GHz Stationary feature Where does it slow? VLA-A 5 GHz 3C120

Galactic Superluminals Black hole - accretion disk systems with x-ray sources and radio jets Like small scale AGN Evolve fast Can see state changes that are too slow in AGN VLBA has too much resolution source moves several beams during observation VLA has too little resolution to study jet in detail GROJ1655

Regions of Enhanced Star Formation Optical/HI VLBA (10 mas res.) MRK273 Much improved short spacing coverage needed (VLBA+NMA) Star formation rate from SNR counts Image thermal gas with few mas resolution From Carilli

Masers Many masers are resolved on all but shortest VLBA baselines Need to add NMA for decent high resolution imaging 2.7 Jy VLA 0.4 Jy VLBA From C. Brogan

EXPECTED VLBA UPGRADES INDEPENDENT OF EVLA 86 GHz being installed now Pointing and surface improvements underway 22 GHz improved amplifiers New data transmission system (Maybe Mark V or S3) Probable increase in sustainable bit rate Limited by station electronics and correlator to ~256 MHz Recording and real time possibilities Big operational and maintainability advantages over current system.

MINIMAL INTEGRATION VLBA data transmission system for some or all NMA antennas Recorders, if used, located at VLA or Socorro using fiber links (est. $35k/site + disks for Mark V) Use existing VLBA correlator Use existing VLBA electronics at VLBA sites Problem: Limited sensitivity Bandwidth less than 2 percent of EVLA bandwidth 256 MHz with new data transmission system on VLBA 16 GHz on EVLA

CORRELATOR OPPORTUNITY EVLA WIDAR correlator can handle VLBI data This is a nearly-no-cost option except interfaces and delays Could be from recordings but real-time much preferred EVLA correlator has extra station inputs Natural breaks at units of 8 stations (32, 40, 48) VLA has 27. NMA + VLA has 37. Each 16 GHz station input can take: 2 stations at 4 GHz each (16 times upgraded VLBA bandwidth) 4 stations at 1 GHz each (4 times upgraded VLBA bandwidth) EVLA correlator can also be the next VLBA correlator Expansion only required for >4 GHz on all stations at once Operationally and psychologically unites the instruments

OPTIONS FOR EVLA PHASE 2 CONTRIBUTIONS TO VLBA/EVLA INTEGRATION 1.) Provide the data connection from 8* VLBA antennas to the EVLA correlator Correlator connections and enhancements LO and IF enhancements for wider bandwidth Data transmission system 2.) Enhance compatibility of station capabilities Upgrade some or all receivers to EVLA standards * Connections and upgrades required for LA and PT regardless because they are in NMA

CORRELATOR OPTIONS 1. Add VLBI interfaces, but no additional baselines This slide for handouts only CORRELATOR OPTIONS 1. Add VLBI interfaces, but no additional baselines Some stations restricted to 4 GHz (assignments not fixed) 4 GHz is 16 times VLBA correlator max so big gain Would complicate scheduling but covers most science Estimate $500k (Note VLBI systems at NMA not needed) 2. Add baselines to cover all stations at full bandwidth Fullest integration but costs roughly $4M (40 to 48 stations) Natural break at 48 allows 3 extra stations (eg GBT …) But transmission of ~100 Gbps from distant stations may be too expensive for a long time (technically feasible now) 3. Second new correlator for NMA+VLBA+Other Estimate (old) $4M for 24 station, 4 GHz of WIDAR design

LO/IF OPTIONS 1: 256 MHz: Use current formatter, BBC’s etc. This slide for handouts only. Costs are rough estimates. LO/IF OPTIONS 1: 256 MHz: Use current formatter, BBC’s etc. Would probably continue to use VLBA correlator No cost per VLBA station beyond Mark V May incur significant costs to interface NMA stations 2: 1 GHz: Sample VLBA 500 MHz IFs New samplers, formatter and data transmission Keeps VLBA LOs and IF converters Estimated cost: $50k per station 3: 4 or 16 GHz: Use EVLA LO/IF system Must replace much VLBA IF and maybe LO systems Estimated cost for 16 GHz: $550k per station

DATA TRANSMISSION OPTIONS This slide for handouts only DATA TRANSMISSION OPTIONS 1. Mark V or equivalent Probably will be done from non-EVLA funds Bandwidth 1 Gbps (256 MHz - more eventually) Can do recording or real-time 2. Real time system on fiber Minimum 512 Mbps (128 MHz, 2 bit samples) Intermediate 4-16 Gbps (1-4 GHz, 2 bit) Ultimate 96 Gbps (16 GHz, 3 bit) - Full EVLA bandwidth Cost, not technology, is the concern Most of cost is in the fiber line and those costs are still very unclear 2000 estimate for customer owned dark fiber: 10 to 100 M$ one time “purchase” plus ~5% annual maintenance fee. Price dropping fast - order of magnitude per year for 5 years in UK.

RECEIVER OPTIONS: 1: No change 2: Key upgrades only. For example: This slide for handouts only RECEIVER OPTIONS: 1: No change 10-20% bandwidths. Some lines missing. No 30 GHz Receivers are more modern than VLA so many ok 2: Key upgrades only. For example: Replace 6 cm with 4 - 8 GHz EVLA receiver (8  ~$70k) Covers 6 GHz masers and good for geodesy and phase referencing Add 30 GHz EVLA receiver (8  ~$135k) Add WVR system to 1 cm receivers Improve low frequencies (Prime focus is available, cost unknown) 3: Full EVLA receiver set (8  ~$550k) Complete frequency coverage How important is this on long baselines? 86 GHz for NMA

This slide for handouts only FREQUENCY BANDS

OPTIONS SUMMARY Full Integration 48 Station correlator ($4M above NMA 40) 16 GHz from VLBA ($4.5M plus fiber access) Full EVLA receiver suite ($4.5M) Partial Integration with powerful capabilities 40 Station correlator ($500k above NMA) 4 GHz from VLBA with new LO/IF ($3M plus fiber access) or 1 GHz with current LO/IF (just sampler and fiber access) Selected receiver upgrades (variable but near $2M) Costs are estimates subject to change.