August 3, 2016 US RMS Futures II, ngVLA Overview ngVLA Overview Mark McKinnon US RMS Futures II August 3, 2016

US RMS Futures II, ngVLA Overview Outline General overview Community engagement Preliminary technical concept Technical issues Summary Additional information

August 3, 2016 US RMS Futures II, ngVLA Overview Next Generation VLA Thermal imaging at milli-arcsecond resolution 10x effective area and resolution of JVLA – ~300x18m antennas; ~300km baselines Frequency range: 1-115GHz Locate in southwest US, centered on present location of JVLA

August 3, 2016 US RMS Futures II, ngVLA Overview ngVLA Location JVLA: elevation ~ 2200m Good 3mm site 550km

August 3, 2016 US RMS Futures II, ngVLA Overview Notional Parameters Carilli et al. 2015, ngVLA memo #5

August 3, 2016 US RMS Futures II, ngVLA Overview Instrument Performance Comparison Angular resolution Effective collecting area

August 3, 2016 US RMS Futures II, ngVLA Overview Science Working Groups Four science working groups (SWGs) established at ngVLA workshop at 2015 AAS – Cradle of Life (co-chairs: Isella, Moullet, Hull) – Galaxy Ecosystems (Murphy, Leroy) – Galaxy Assembly through Cosmic Time (Casey, Lacy, Hodge) – Time Domain, Cosmology, Physics (Bower, Demorest) SWG white papers (ngVLA science goals) published in arXiv and ngVLA memo series in Oct 2015 Preliminary science requirements developed from white papers (Carilli)

August 3, 2016 US RMS Futures II, ngVLA Overview Meetings and Community Engagement ngVLA Science Workshop #1, AAS, Seattle, Jan 4, 2015 ngVLA Technical Workshop #1, Pasadena, CA, Apr 8-9, 2015 – Topics: antennas, correlators, receivers – Conclusion: no technical obstacles to achieving ngVLA goals ngVLA Technical Workshop #2, Socorro, Dec 8-9, 2015 – Topics: operations concept, data digitization & transmission, computing architecture, time and frequency distribution US RMS Science Futures in the 2020s, Chicago, Dec – Funded by AUI and Kavli Foundation ngVLA Science Workshop #2, AAS, Kissimmee, FL, Jan 4, 2016 US RMS Science Futures II, Baltimore, Aug 3-5, 2016

August 3, 2016 US RMS Futures II, ngVLA Overview Antennas and Receivers Preliminary antenna concept (Lamb, Srikanth) – Diameter: 18m (12m-25m under consideration) – Optical configuration: offset Gregorian, feedarm on low side – Mount: alt-az Receiver package concept (Grammer, Weinreb, Soriano) – Frequency coverage: continuous over ~10-50GHz and GHz, with low frequency coverage down to ~1GHz – Receivers cryogenically cooled, with multiple receiver bands in a cryostat. Two configurations under consideration: 6 bands in 3 cryostats (baseline) 3 bands in a single cryostat (ultra-wideband feeds)

August 3, 2016 US RMS Futures II, ngVLA Overview Data Transmission (DTS) and Correlator Output of most receivers digitized at the receiver output using miniaturized DTS modules – Highest frequency receiver will have a single block down-conversion prior to its sampler – ADC output converted to optical, combined on optical fiber, and transmitted to a central processing facility Various options for time & frequency distribution being explored – GPS-disciplined masers, fiber optic connection to central site, satellite-based timing Correlator (D’Addario) – Likely FX architecture – Technology implementation (FPGA, GPU, ASICS) under discussion

August 3, 2016 US RMS Futures II, ngVLA Overview Science Operations and Computing ngVLA is envisioned to be a general purpose, PI-driven, pointed instrument. Implications: – Variety of observing modes to support PI science goals – Full suite of project lifecycle tools (e.g. proposal submission, observation preparation, scheduling, archive access, helpdesk) – Flexible data reduction system – Increased complexity for Science Ready Data Products (SRDPs) – Data proprietary period Fully dynamic scheduling to maximize observing efficiency and to facilitate rapid response for time domain science Computing design drivers: PI-driven operations model, large data volumes/rates, and minimal operations cost (Kern, Butler)

August 3, 2016 US RMS Futures II, ngVLA Overview Technical Issues under Discussion Phase calibration (Woody, Butler) – Paired antennas, dedicated reference array, water vapor radiometers, fast switching, self-calibration Array configuration (Condon, Butler) – Sensitivity to low surface brightness – Fixed or moveable antennas – VLBI implementation Antenna optical configuration (Lamb, Srikanth) – offset Gregorian, symmetric Cassegrain, other Receiver band definition (Grammer, Weinreb, Soriano) – Tradeoffs between system temperature, aperture efficiency, beam shape, operating cost, etc. with receiver band ratio

August 3, 2016 US RMS Futures II, ngVLA Overview Summary ngVLA: an enticing/exciting concept for the future of radio astronomy Significant support from user community in developing the ngVLA science case via SWGs Community engagement in development of ngVLA science case and technical concept through sponsored workshops Progress has been made in advancing ngVLA science case and technical concept; much work remains to prepare for DS2020

August 3, 2016 US RMS Futures II, ngVLA Overview Additional Information ngVLA webpage – Sign-up for ngVLA mailing list – ngVLA memo series – ngVLA science working groups –

August 3, 2016 US RMS Futures II, ngVLA Overview science.nrao.edu public.nrao.edu The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc.