ngVLA Simulation Tools & Materials
ngVLA Configuration Tools
We are expecting to have the ngVLA configurations included in the release of CASA version 5.3. Addtionally, an updated CASAGuide is forthcoming. In the interim, we have the following materials available for direct download:
Configuration Files for CASA (updated April 24, 2018): The files below are for the reference configuration of the ngVLA as approved by the project in April, 2018. These should be used for simulations and calculations that explore the science capabilities of the ngVLA. We expect that such investigations will lead to suggested modifications to these notional configurations for specific science cases, and hope the community will report on such findings via ngVLA memos and/or refereed publications.
We note that imaging with heterogenous arrays -- i.e., arrays with different diamter antennas -- (e.g., ngVLA + SBA or VLBA + ngVLA) is not currently supported in teh current CASA release (except for ALMA).
- ngvla-revB.cfg: The reference configuration of the main array. This array includes 214 antennas of 18m diameter, to baselines up to 1000 km. The array will not be reconfigurable, hence we have designed a configuration that performs well on a range of angular scales, from 0.01" to 1" at 30GHz. The Spiral214 array can be characterized by three scales, starting from the core with 94 antennas in a semi-random distrbution within a region of 1km diameter. Extending from the core are 74 antennas in a five armed spiral pattern out to 30km baselines (the "plains" array). The remaining 46 antennas are then distributed mostly to the south, in a rough three arm spiral pattern, out to a maximum baseline of 1000km, into Texas, Arizona, and
Mexico. The array configuration is practical, accounting for logistical limitations such as topography and utility availability. Investigations are underway to improve the imaging sensitivity and fidelity while accounting for additional limitations such as local RFI sources and land management and availability.
Numerous memos and science studies have been published that address the imaging parameters for optimal performance (sensitivity, PSF). We refer interested parties to the ngVLA memo series, and in particular, memos: 16, 30, 35, 41.
- ngvla-core-revB.cfg: This configuration is just 94 core stations from the full 214 antenna array above. This configuration is suitable for imaging lower surface brightness regions, and provides a resolution of about 2" at 30GHz.
- ngvla-plains-revB.cfg: This configuration is just the 168 antennas (94 core stations + 74 antennas included in the 5 spiral arm pattern) located on the plains of San Agustin. This configuration is suitable for imaging with similar spatial scale capabilities of the existing VLA.
- ngvla-sba-revB.cfg: A small array of 19 close-packed antennas of 6m diameter to complement array core for very low surface brightness imaging. The use of 4 18 m antennas in total power mode to fill in the uv-hole left by the SBA is being investigated. NOTE: In order to get the correct beam for the SBA (6m antennas), a special procedure is required (see page 11 of ngVLA memo 43).
- ngvla-gb-vlba-revB.cfg: Includes the full 214 antenna configuration above, with an additional 10 continential-scale antennas: 5 18m antennas randomly placed at the Green Bank site and individual 18m antennas located at the existing Saint Croix, Hancock, North Liberty, Brewster, Owens Valley, Mauna Kea VLBA sites.
- A technical note on how to run ngVLA simulation, and in particular, how to set realistic noise levels in them.
- A zip file including all above configurations, the technical note on running the simulation, and a README file.
ngVLA Receiver Configuration
A summary of various receiver configurations being considered for the ngVLA (updated March 28, 2018).
ngVLA Sensitivity Calculator
The ngVLA Sensitivity Calculator is under development. Please refer to the Performance Table under the current Reference Design page to compute your sensitivity estimates for now.