Features

Quick Access to SRDP Features: NRAO Archive data.nrao.edu

 Download calibrated Measurement Sets for VLA or ALMA:

  1. Go to https://data.nrao.edu
  2. Search for some data (e.g., project code, target name, position/radius)
  3. Click the '+' to see more detail about the project
  4. For ALMA - Click the blue 'Download Restored MS' button for the desired data
  5. For VLA - Click the 'Select for Download icon' and click 'Download'

Run ALMA User-Defined Imaging (AUDI):

  1. Follow steps 1-3 from above
  2. Click the blue 'Download Restored MS' button for the desired data
  3. Fill out the dialog box for a frequency-based or velocity-based cube
  • A valid setting for the frequency-based cube is filled by default for the selected spectral window

 See the tutorial video for AUDI for more detail.

ALMA User-Defined Imaging (AUDI)

User-defined data cubes can be produced for proprietary ALMA data (by the PI or delegee) and non-proprietary data. Users can specify the spectral width and channel width in frequency or velocity units to produce a data cube that may better fit their science needs. Continuum imaging is also produced as part of this process in case it is needed for interpretation of the spectral line data. The cube imaging process makes use of the ability to restore a calibrated measurement set and the ALMA imaging pipeline. This feature has the same limitations as the calibrated measurement set download in that it can only operate on pipeline-reduced Cycle 5 data and beyond.

The imaging pipeline will operate using the current version of the ALMA imaging pipeline to take advantage of the most recent improvements to continuum finding, automasking, and self-calibration. Thus, imaging products may be different and likely superior to those delivered with an ALMA project by default.

The cube imaging process functions as follows:

  1. The selected dataset is restored to a calibrated state using the same process for download of a calibrated measurement set
  2. Imported into the ALMA imaging pipeline
  3. Custom cube(s) and continuum images are produced using a special imaging pipeline recipe which includes automated self-calibration

ALMA Calibrated Measurement set download

PIs and Delegees will be able to download calibrated measurement sets for their proprietary ALMA data once ingested into the ALMA archive and mirrored in the NRAO archive. Archive users can also download calibrated measurement sets for any non-proprietary data. Calibrated measurement sets can currently only be downloaded for datasets that were fully calibrated by the ALMA pipeline; manual reductions are not supported. Only Cycle 5 data and later from the 12m array and ACA can be restored using this process due to the way the data were archived in earlier cycles.

The calibrated measurement sets are generated on-the-fly when requested. As such, there will be a time lag between when a request is submitted and when the data are ready to be downloaded. The time for the calibrated data to be ready for download depends strongly on the size of the dataset. The restoration process reapplies the flagging done by the pipeline and apply the calibration tables produced and archived by the ALMA pipeline. The manual reductions follow a different workflow and are not compatible with being restored to a calibrated state in the same manner.

Time until dataset ready for different raw data sizes:

10 GB  -  ~1 hr

100 GB - ~10 hr

1 TB - ~60 hr
 

Quality Assured calibration for the VLA

The VLA calibration pipeline has been run on data immediately after collection since 2013 and operates on all data that are setup properly to run through the VLA pipeline. Data that are properly setup include: a Bandpass calibrator, a flux density calibrator, complex gain calibrators visited at recommended cycle times, and properly set scan intents in the Observation Preparation Tool (OPT). For bands that require reference pointing, the pointing is conducted at the recommended once per hour time interval. Pulsar data and Solar data are not processed in the VLA pipeline; the pipeline also does not currently support P-band data.

Data that are successfully processed by the pipeline for selected projects will then be reviewed by NRAO Data Analysts (DAs) and Scientists following a Quality Assurance (QA) process. As part of the QA process, the DAs and/or Scientists may perform additional flagging on calibrators and targets, and re-run the pipeline with additional flagging, if necessary. The goal is to provide the users with a calibrated dataset that is ready for imaging. The final calibration and flagging will be ingested into the archive. Raw data will still be available to the PIs and Co-Is immediately.

The calibration pipeline will still be run on all data, but they may not go through the QA process.

Spectral line datasets are not currently be supported by the QA process. The continuum portion of spectral line datasets will still be QAed. Users requiring spectral line observations should still follow the instructions on https://science.nrao.edu/facilities/vla/data-processing/pipeline#section-22 to calibrate their VLA spectral line data using the pipeline.

VLA Calibrated Measurement set download

PIs and Co-Is will be able to download calibrated measurement sets for their proprietary VLA data once calibration and QA have been performed. Archive users can also download calibrated measurement sets for any non-proprietary data. Calibrated measurement sets can currently only be downloaded for datasets that were fully calibrated by the VLA pipeline from mid-August 2016 and later (CASA 4.7.1 and later). Pulsar data, Solar data, and P-band  are not supported in the VLA pipeline.

The calibrated measurement sets generated on-the-fly when requested. As such, there will be a time lag between when a request is submitted and when the data are ready to be downloaded. The time for a calibrated data to be ready for download depends strongly on the size of the dataset. The restoration process applies hanning smoothing, reapplies the flagging done by the pipeline, applies the calibration tables produced and archived by the VLA Pipeline, and runs statistical weighting.

Updated Archive Interface

The archive frontend has been completely revamped to feature an updated interface to enable data discovery. The archive serves data for the VLA (legacy data and Jansky VLA), ALMA, VLBA, and GBT (partial).

Images from the VLASS survey are also being served by the archive, except for the VLASS Pilot data.

Users can search for data in a variety of ways and initiate restorations of datasets to a calibrated state in the archive.

Connect with NRAO

The National Radio Astronomy Observatory and Green Bank Observatory are facilities of the U.S. National Science Foundation operated under cooperative agreement by Associated Universities, Inc.

Founded in 1956, the NRAO provides state-of-the-art radio telescope facilities for use by the international scientific community. NRAO telescopes are open to all astronomers regardless of institutional or national affiliation. Observing time on NRAO telescopes is available on a competitive basis to qualified scientists after evaluation of research proposals on the basis of scientific merit, the capability of the instruments to do the work, and the availability of the telescope during the requested time. NRAO also provides both formal and informal programs in education and public outreach for teachers, students, the general public, and the media.

The National Science Foundation (NSF) is an independent federal agency created by Congress in 1950 "to promote the progress of science; to advance the national health, prosperity, and welfare; to secure the national defense..."

AUI collaborates with the scientific community and research sponsors to plan, build, and operate cutting-edge facilities. We cultivate excellence, deliver value, enhance education, and engage the public.