Data Access

by Stephan W. Witz last modified Jul 06, 2012 by Stephan Witz

The online archive contains all VLA data since observing started in 1976, and also serves the user community with EVLA data. The entire archive is now on disk, and is available via the Archive Access Tool (AAT) at http://science.nrao.edu/facilities/evla/archive/evla/ . This interface provides a basic data retrieval tool if you know the program code of your observations. It also provides an advanced query tool which enables searches based on a large number of user-specified criteria. Data can be downloaded via standard ftp protocols and via shipment of physical harddisks (see https://science.nrao.edu/facilities/evla/data-archive/data-shipment for the disk shipment policy). With the exception of some rapid response and large proposals, (E)VLA data associated with a given proposal normally are restricted to proprietary use by the proposing team for a period of 12 months from the date of the last observation in a proposal (Note: data taken more than 12 months previously may still be proprietary, if additional data for the same proposal have been taken within the last 12 months). Proprietary data may be downloaded by the observing team by logging in to the AAT with the my.nrao.edu/PST user account or by making use of the project key (see The Observations and Remote Observing).

Data are stored in the archive in the Science Data Model (SDM) format that will be used by both the EVLA and ALMA. They are available through the AAT in one of two formats:

- As a CASA Measurement Set.
- In UVFITS format, which can be read by either AIPS or CASA.

The raw SDM format will only be available by special request submitted through the NRAO Helpdesk.

Note that some archival data have known problems which, together with the possible fix, are listed at http://www.vla.nrao.edu/astro/archive/issues/ .