Archiving at NRAO’s VLA and VLBA Telescopes

Abstract

All raw data recorded by the Very Large Array (VLA) since it began operation in 1980 have been archived, test observations and calibrations as well as program observations. The reels of tape are kept in a vault in the control building of the VLA on the Plains of San Augustin in New Mexico; the vault was filled several years ago and so recordings for recent years are in a trailer parked outside the control building. The data are in the public domain, by policy, with a proprietary period of 18 months for program observations. A subset of the observation catalog (all non-calibrator observations with duration longer than one hour) is distributed as a set of floppy disks (MS-DOS format) with a search program (for MS-DOS); the full catalog is available on a computer at the Array Operations Center in Socorro, New Mexico. One technical problem is that the existing catalog doesn’t tabulate which reel of tape in the vault has which day’s data. Reel numbers must be obtained from a log book at the VLA site. But the data tapes can be located in the vault, they are coded in a modest set of reasonably self-documenting formats, and a portable program which is exported by the National Radio Astronomy Observatory (NRAO) in all AIPS (Astronomical Image Processing System) kits can be used to read files copied from them.