KEYWORDS: Antennas, Radio astronomy, Observatories, Telescopes, Optical correlators, Data storage, Data processing, Data centers, Control systems, Printed circuit board testing
A future large area radio array optimized to perform imaging of thermal emission down to milliarcsecond scales is currently under consideration in North America. This `Next Generation Very Large Array' (ngVLA) will have ten times the effective collecting area and ten times longer baselines (300 km) than the JVLA. The large number of antennas and their large geographical distribution pose significant challenges to ngVLA operations and maintenance. We draw on experience from operating the JVLA, VLBA, and ALMA to highlight notable operational issues and outline a preliminary operations concept for the ngVLA.
We give an overview of the scientific commissioning and early operation of the Karl G. Jansky Very Large Array (VLA). The Expanded VLA Construction Project was a decade-long project to transform the capabilities of the VLA, culminating in its re-dedication in 2012 as the Jansky VLA. The need to keep a vibrant and engaged user community throughout the entire construction project translated into operational requirements (one of which was allowing the minimum down-time possible), and the need for a mechanism to provide the community with early access to the new capabilities alongside on-going construction and commissioning, using a staged approach. This access was enabled during the EVLA Construction Project by defining an Open Shared Risk Observing (OSRO) program for the general community, and a Resident Shared Risk Observing (RSRO) program for those requesting capabilities not fully commissioned in exchange for a period of residency to help commission and test those capabilities with the assistance of NRAO staff. The OSRO program has become the General Observing (GO) program in full operations, and the RSRO program has continued as a means of maintaining, and adding to, an active pool of users with innovative ideas for new capabilities, driven by their science. Besides the new technical capabilities, the start of full operations of the Jansky VLA also introduced full dynamic scheduling, including the ability for fast (less than 24 hour) response to triggers and targets of opportunity, and the delivery of pipeline-calibrated visibility data for continuum projects. We discuss some of the challenges resulting from the new capabilities and operational model for the VLA.
KEYWORDS: Data archive systems, Data storage, Calibration, Visibility, Telescopes, Standards development, Observatories, Algorithm development, Data modeling, Software development
The Expanded Very Large Array (EVLA) project is the next generation instrument for high resolution long-millimeter to
short-meter wavelength radio astronomy. It is currently in early science operations, with full science operations to
commence in January 2013. The EVLA construction project provided new software for all aspects of operation of the
telescope, including both that required for controlling and monitoring the instrument and that involved with the scientific
workflow. As the telescope transitions into full operations we are also developing the software and operations policies
that allow us to manage the large amounts of data collected by the instrument (up to terabytes for a single observation;
petabytes per year for all observations). We present an overview of our data management software and policies for the
EVLA, as well as some early experience we have gained with the storage and distribution of data, post-processing,
automatic processing, and centralized reprocessing of data, and storage of derived products back into our science
archive.
Begun in 2001 with a total budget of around $100M, the Expanded Very Large Array (EVLA) project is the only major
upgrade to the VLA undertaken since the interferometer was dedicated in 1980. The goal of this 11-year long project is
to improve all the observational capabilities of the original VLA - except for collecting area and spatial resolution - by
at least an order of magnitude. To achieve this, the 28 VLA antennas have been modernized with new digital data
transmission systems that link to a new, wideband, fiber optic digital LO/IF system, and eight new sets of cooled
receivers are under construction that will offer full frequency coverage from 1 to 50 GHz, with instantaneous bandwidths
up to 8 GHz provided by two independent dual polarization frequency pairs. The new WIDAR correlator provided by
NRAO's Canadian EVLA partner replaced the old VLA correlator in early 2010 and is currently undergoing
commissioning.
The long duration of the EVLA construction project coupled with the need to maintain the scientific productivity and
user base of the telescope obviously precluded shutting down the old array while new infrastructure was built and
commissioned. Consequently, the construction plan was based on the fundamental assumption that the old VLA would
continue to operate as new EVLA capabilities gradually came online; in some cases, additional complexity had to be
designed into new hardware in order to maintain transitional interoperability between the old analog and new digital
systems as the latter were installed and commissioned. As construction has advanced, operations has increasingly had to
coexist side by side with EVLA commissioning and verification. Current commissioning plans attempt to balance
making new EVLA capabilities available to the user community as soon as they have been installed and verified, and
maintaining a stable and robust end-to-end data acquisition and delivery process for the user community.
Conference Committee Involvement (4)
Observatory Operations: Strategies, Processes, and Systems X
17 June 2024 | Yokohama, Japan
Observatory Operations: Strategies, Processes, and Systems IX
19 July 2022 | Montréal, Québec, Canada
Observatory Operations: Strategies, Processes, and Systems VIII
14 December 2020 | Online Only, California, United States
Observatory Operations: Strategies, Processes, and Systems VIII
13 December 2020 | San Diego, California, United States
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