ngVLA Tools & Materials
ngVLA Configuration Tools
NOTE (7/14/21): A new configuration (Rev. D) has recently been
developed by the ngVLA Imaging and Calibration work group as part of Conceptual Design Review (CoDR) preparation. The corresponding requirements and description documents are being prepared for the CoDR, however the Rev. D configuration files can be obtained now for your ngVLA simulation work. Please contact Chris Carilli at ccarilli-at-nrao.edu to obtain them.
A CASA guide that shows how to create simulated data for the ngVLA including a model repository is available at this link.
Configuration files for each ngVLA subarray can be downloaded below. Alternatively, these configuration files are included as part of CASA distributions 5.5 and greater. They can also be added to older versions of CASA as described in the Simulating ngVLA Data CASA guide.
Configuration Files for CASA (updated Dec 3, 2018): The files below are for the reference configuration of the ngVLA as approved by the project in July 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 diameter antennas such as ngVLA + SBA — is not currently supported in the current CASA release (except for ALMA).
- ngvla-revC.cfg: The ngVLA reference array configuration. This array includes 244 antennas of 18m diameter, and it extends over a maximum baseline of ~8860 km. The array will not be reconfigurable, hence we have designed a configuration that performs well on a range of angular scales, from ~0.001" to 1" at 30 GHz. The ngVLA reference array is composed of the Main interferometric array plus the Long Baseline Array (LBA), i.e., all of the 18m antennas of the ngVLA. The only antennas not appearing in this reference array are the 6m antennas of the Short Baseline Array (SBA), which is provided in a separate subarray below.
- ngvla-main-revC.cfg: The ngVLA Main interferometric array (also known as the Spiral214) includes 214 antennas of 18m diameter and has baselines up to ~1000 km. The Spiral214 array can be characterized by three scales, starting from the Core with 94 antennas in a semi-random distribution within a region of 1 km diameter. Extending from the Core are 74 antennas in a five-armed spiral pattern out to 30 km baselines (the Plains array). The remaining 46 antennas (the Mid-Baseline array) are then distributed mostly to the South in a roughly three-arm spiral pattern, extending into parts of Texas, Arizona, and Mexico. Each of these three scales is broken out into separate subarrays in the following configuration files.
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, in particular memos 16, 30, 35, and 41.
- ngvla-core-revC.cfg: This configuration consists of the 94 core antennas from the full 244 antenna array above. This configuration is suitable for imaging lower surface brightness regions, and provides a resolution of about 2" at 30 GHz.
- ngvla-plains-revC.cfg: This configuration is just the 168 antennas (94 core stations + 74 antennas included in the five spiral arm pattern) located on the Plains of San Agustin. This configuration is suitable for imaging spatial scales similar to the existing VLA.
- ngvla-mid-subarray-revC.cfg: This configuration contains only the 46 antennas which are in the Main array but not the Plains or Core subarrays.
- ngvla-lba-revC.cfg: This configuration, having only the 30 antennas located in 10 different continental-scale stations, is another subarray of the full 244 antenna array above. Long baseline stations are located in Hawaii, Washington, California, Iowa, Massachusetts, New Hampshire, Puerto Rico, the US. Virgin Islands, and Canada.
- ngvla-sba-revC.cfg: This Short Baseline Array (SBA) has 19 close-packed antennas of 6 m 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. The SBA is the only subarray which is not part of the full 244 antenna reference configuration file. NOTE: In order to get the correct primary beam for the SBA (6 m antennas), a special procedure is required (see page 11 of ngVLA memo 43). Support for heterogeneous arrays other than ALMA (e.g., simultaneously using the ngVLA 18 m and 6 m antennas) is currently being commissioned.
- A technical note on how to run ngVLA simulations, 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
The receiver configuration has progressed since the Reference Design, with an improved cascade analysis for the preferred 6-band concept.
This latest system noise estimate (updated Oct. 28, 2021) reflects the updated cascade analysis and refinements based on ngVLA Memo #96.
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.