NRAO VLA Archive Survey (NVAS) Data Products

All NVAS data is archived at the NRAO Array Operations Center, and is accessible over the network file system. Data is currently divided between three directories (corresponding to different hard disks):

• /home/archive_surveys/pipeline/
• /home/archive_surveys2/pipeline/
• /home/archive_surveys3/pipeline/

Each of these directories contain two subdirectories:

• position/
• project/

The position directory holds the single-source data, and the project directory holds the multisource data.

position subdirectory

The position directory contains subdirectories with names of sky positions in J2000 coordinates. For example: J173105.5+875413/.

This directory will hold all single-source data observed at this coordinate for all data sets (projects) processed by the pipeline. An example of one data set's single source files is:

DESCRIPTION	EXAMPLE (from J173105.5+875413)
FITS Image	14.9I0.53_AL364_1995NOV05_1_546.U1.43M.imfits
JPEG Image (full size)	14.9I0.53_AL364_1995NOV05_1_546.U1.43M.jpg
JPEG Image (thumbnail)	14.9I0.53_AL364_1995NOV05_1_546.U1.43M.JPG
Real-imagainary visibility plot	14.9F27BB_AL364_1995NOV05_1.ri.gif
uv-coverage plot	14.9F27BB_AL364_1995NOV05_1.uv.gif
Visibility amplitude plot	14.9F27BB_AL364_1995NOV05_1.vis.gif
Single-source calibrated visbility data	14.9F27BB_AL364_1995NOV05_1.uvfits

File names are described in detail on LorantSjouwerman's NVAS pilot web page.

A single position subdirectory may contain multiple sets of the above files, each from some different data set in the visibility archive. In the example directory I referenced above, there are at least 5 sets of these files. Sky position directories (e.g. J173105.5+875413/) may contain a removed subdirectory as well, which holds low-quality data we do not intend to distribute as part of the survey. (There are also HTML files in the position subdirectories. LorantSjouwerman uses these to build his web interface to this pipeline data. If you want to know about the HTML files, you should talk to him.)

project subdirectory

The project directory contains subdirectories with names of VLA project codes. For example: AR0231/.

This directory will hold all multi-source data products for this project code. An example of one data set's multisource files is:

DESCRIPTION	EXAMPLE (from AR0231)
AIPS calibrated visibility data	AR0231_1991APR15_1_8.46F26DD.uvfits
AIPS calibration tables (without data)	AR0231_1991APR15_1_8.46F26DD.clfits
C-shell script that starts AIPS processing	AR0231_1991APR15_1.0.aips.run
AIPS log	AR0231_1991APR15_1.0.aips.log
C-shell script that prepares (FILLs) data	AR0231_1991APR15_1.fill.run
AIPS data preparation (FILLing) log	AR0231_1991APR15_1.fill.log
Data download log	AR0231_1991APR15_1.data.log
C-shell script that moves data (when needed)	[pcode]_[date]_[#].move.run
Data moving log (when needed)	[pcode]_[date]_[#].move.log

Again, multiple sets of these files may exist in a project subdirectory, each for a different observing day. In the example I reference above (AR0231/), there are at least 8 sets of these files. (Again, there are also HTML files that LorantSjouwerman uses for the NVAS pilot Web site interface.)