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VLA Low-band Ionosphere and Transient Experiment (VLITE)


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The astronomical imaging component of the VLITE project is based on a dedicated pipeline that was developed by NRL within the Obit and AIPS software packages.

VLITE data support the VLA through value-added PI science while the large field-of-view of VLITE enables a new stand-alone astrophysics component to study individual sources or samples of sources that fall well outside the primary observing band field-of-view.

Examples of total intensity radio images are shown above. The images of NGC 6946, W3 Main and W3 North Complexes, 3C 129, and DA 240 were fully processed using the VLITE astrophysics data processing pipeline. In the case of Abell 2255 and Arp 299, the data were calibrated using the processing pipeline and then they were imaged manually.

Astrophysics Data Processing Pipeline

The astrophysics data processing pipeline includes:

  • automated excision of radio frequency interference
  • delay calibration
  • bandpass and flux density scale calibration
  • imaging of each target
  • up to two rounds of phase-only self-calibration (if feasible) and (when appropriate) amplitude self-calibration
The output of the data processing pipeline includes:
  • observation logs and source catalog
  • antenna diagnostic plots
  • calibration tables
  • calibrated uv data
  • multi-frequency image cubes
  • broadband total intensity (Stokes I) images
The images and source catalog feed back into the transient search components of the project.

The quality of VLITE images produced depends on a number of factors, including the total on-source time. The visibility-plane filling factor for data plays a critical role in determining the impact of sidelobes on the sparse VLITE array. For any given total integration time, VLITE data which are spread over a large hour angle will generally have much better image fidelity than data from the same total time observed over a smaller (continuous) hour angle.

Below we provide examples for several VLA configurations of the typical field-of-view (FoV) processed by the VLITE astrophysics pipeine, the synthesized beam (θ), and the typical rms (σ) level in a 10 minute VLITE image. The rms level is appropriate for the 16-18 antenna VLITE observations, data from the VLITE 10 observations (November 2014 - July 2017) are significantly less sensitive.

VLITE 18 Antenna Specification

Config. FoV θ σ (10 min)
A 5" 2.1 mJy
B 3.5° 15" 5.4 mJy
C 45" 8.6 mJy
D 150" 21.8 mJy

Modified on Friday, 02-Jun-2023 11:03:52 MDT