1. Atacama Large Millimeter/submillimeter Array Expanded Very Large Array Robert C. Byrd Green Bank Telescope Very Long Baseline Array The Expanded Very Large Array Rick Perley 1 and Sean Dougherty 2 1 NRAO, Socorro, NM 2 DRAO/HIA/NRC, Penticton BC

2. EVLA The Expanded Very Large Array The Expanded Very Large Array is a $90M upgrade of the Very Large Array. – Project began in 2001, will be completed in 2012 – on time, on spec, on budget. The EVLA will multiply by orders of magnitude the observational capabilities of the VLA. Key goals are: – Full frequency coverage from 1 to 50 GHz. – Up to 8 GHz instantaneous bandwidth, per polarization – New correlator with unprecedented capabilities – ~3  Jy (1- , 1-Hr) point-source continuum sensitivity at most bands. – ~1 mJy (1- , 1 km/sec, 1 Hr) line sensitivity at most bands. 2

3. EVLA Overall EVLA Performance Goals Providing orders of magnitude improvements in performance! ParameterVLAEVLAFactor Continuum Sensitivity (1- , 1 hr.)30  Jy3  Jy 10 Maximum BW in each polarization0.1 GHz 8 GHz80 # of frequency channels at max. BW1616,3841024 Maximum number of freq. channels5124,194,3048192 Coarsest frequency resolution50 MHz2 MHz40 Finest frequency resolution381 Hz0.12 Hz3180 # of full-polarization spectral windows26432 (Log) Frequency Coverage (1 – 50 GHz)22%100%5 3

4. EVLA Major EVLA Milestones All 28 antennas now converted to EVLA standards. VLA correlator was shut down on January 11. New EVLA correlator turned on March 2. Wideband Interferometric Digital ARchitecture (WIDAR) correlator contributed by Canada EVLA ‘early science’ OSRO and RSRO programs began March 2010 and continue through end of 2011. 2 GHz bandwidth available by June 2010. Correlator installation complete July 2010. Full bandwidth (8 GHz) available on all antennas late-2011. Receiver implementation will be completed end of 2012. 4

5. EVLA The ‘WIDAR’ Correlator A 10 petaflop special-purpose computer. – Designed and built by Canadian HIA/DRAO. Major capabilities: – 8 GHz maximum instantaneous bandwidth, with full polarization. – 16384 minimum, 4.2 million maximum frequency channels – 64 independently tunable full polarization ‘spectral windows’, each of which effectively forms an independent ‘sub-correlator’. – Extensive special modes: pulsar gating/binning, phased array, VLBI- ready, burst modes, and more. Most of this correlator now in place at the VLA site. Fundamental capabilities will be developed first, with specialty modes later. 5

6. EVLA Early EVLA Results Results shown from: – A 12-antenna sub-array used to test WIDAR-0 prototype. 8192 channel, Full polarization, Eight adjacent spectral windows – The full WIDAR, with all antennas. Eight tunable spectral windows For more early results, see posters: – WIDAR – the High-Performance Heart of the EVLA (DRAO WIDAR team) – EVLA and Early Galaxies: Current Status (Carilli et al.) – Zeeman Effect at 36 and 44 GHz from Class I Methanol Masers (Momjian and Sarma) 6

7. EVLA 3C147 Deep Field @ 1440 MHz 12 antennas, 110 MHz bandwidth, 6 hours integration Fidelity ~ 400,000:1 Peak/rms ~ 850,000:1 The highest fidelity image ever made with the VLA – using only a fraction of the full capability! The artifacts are due to non- azimuthal symmetry in the antenna primary beams. – Illustrates the need for advanced calibration/imaging software. 7 First Null Primary Beam Half Power

8. EVLA Orion-KL Spectrum – 3 GHz Wide 8 Three short obs. of Orion, each 1024 MHz wide, with ~1.5 km/sec velocity resolution and 2.5” spatial resolution, show 31 strong lines. From ammonia (NH3): 8 lowest meta-stable inversion transitions (J,K) = (1,1) to (8.8) (6,6) line from 15 NH 3 isotopologue, the 4(1,4)-4(0,4) line from NH 2 D. meta-stable (9,8) & (10,9) lines, Two E/A doublets of methyl formate: CH 3 CHO OCS 2-1 Three lines from SO 2 Ten strong methanol maser lines from E-type series (J=2 – 11). One unidentified line Numerous weak lines. 24072 channels

9. EVLA Orion-KL: Zooming in … 9 Left Side: The lowest 1.0 GHz, showing identifications. Right Side: The two lowest meta-stable transitions, showing blended hyperfine structure. Two SO 2 lines

10. EVLA Spectra from the 128 x 128 x 24012 data cube 10 Moment-0 Image End to end processing done in CASA by Steve Myers Data Cube available at: http://science.nrao.edu/evla/ projectstatus/index.shtml

11. EVLA EVLA K-band Observations of massive young stellar objects in NGC6334-I 8 x 8 MHz subbands with 256 channels, 0.4 km/sec; 10 minutes on source!!!! Test for RSRO project AB1346 (PI Crystal Brogan): “A Diagnostic K-band Survey of Massive Young Protostellar Objects” which will use 16 subbands NGC63 34-I maser s NH 3 (3,3)

12. EVLA Crystal’s ‘RSRO’ Project : A Diagnostic K-band Survey of 30 Massive Protostellar Objects 12 In the “best case” scenario we will use 32 subbands (solid and dotted lines above) which includes a number of rare and deuterated species In the “great case” scenario we will use 16 subbands (solid lines above) Current tests uses 8 of the subbands above

13. EVLA Early Science Programs Two early science programs: March 2010 through December 2011. Open Shared Risk Observing (OSRO): – A ‘business as usual’ observing protocol. – Observers will access EVLA in same manner as current for VLA. – Initial configuration provides 512 spectral channels with one or two spectral windows of 128 MHz (maximum) each. Resident Shared Risk Observing (RSRO): – Must be resident in Socorro for at least 3 months. – Participants will have access to more extensive observing capabilities. – Participants will assist NRAO staff in expanding capabilities – Observing time proportional to length of residency. – 27 proposals received on first call, 13 have been accepted. For details, see: – http://science.nrao.edu/evla/earlyscience/osro.shtml 13

14. EVLA 14 WIDAR Growth: 2010+ Observational capabilities will grow rapidly through 2010 - 11 All early observations will be with the ‘fundamental homogeneous correlator setup’ – All spectral windows adjacent, with same width & channelization, arranged to maximize total bandwidth (BW) coverage Resident observers (RSRO Program) should have access to: – 2 GHz/polarization BW (all antennas) by mid-2010 – 8 GHz/polarization BW (all antennas) by end of 2011. – Recirculation (increased spectral resolution) by late 2010 – Independent spectral window tuning by early 2011 – Flexible resource allocation (trading spectral windows for more spectral resolution) by mid 2011

15. EVLA Summary EVLA is now conducting science observations with all antennas and unprecedented new capabilities Wide-band (full tuning range) receivers available on all antennas – Highest frequency bands (18 – 50 GHz): mid 2010 – 4 – 8 GHz: end 2010 – Remaining four bands: 2012 Ever Increasing Science opportunities: Mar 2010 - Dec 2011 – Basic modes via OSRO Program: 256 MHz max BW, and you stay home – Advanced modes via RSRO Program: 2 – 8 GHz max BW, and you come to Socorro – Specialty modes as implemented, guided by user interest Full Regular Observing begins Jan 2012 15

16. EVLA 16 Full-Bandwidth Availability Timescale During transition, L, C, and X band receivers are on all antennas.

17. EVLA Spectral Windows Continuity 17 Eight continuous subbands, each of 128 MHz, spanning 1 – 2 GHz band. 1.024 GHz Satellites Aircraft Navigation Cellphones Single baseline, ampscalar average, showing RFI, but also extensive ‘empty space’. These are raw data, with no bandpass correction. Same data, vector average, showing how RFI is decohered over a few minutes integration. GPS