1. 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?

2. 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

3. 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

4. Resolution vs. Frequency

5. 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

7. 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)

8. 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.

9. 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

10. 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

11. 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

12. 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

13. 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.

14. 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

15. 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

16. 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

17. 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

18. 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

19. 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.

20. 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 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

21. This slide for handouts only
FREQUENCY BANDS

22. 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.