Subsidiary data about uv database and image files are written in “extension files.” These include, for example, history records (HI files), plot instructions (PL files), calibration solutions (SN files), ad nauseum. Some extension files can become large. A history file uses 1024 bytes for every 14 history records, a small amount under most circumstances. A plot file is normally small, but the output from GREYS can be as large as one plane of the image and the output of KNTR is larger by a factor of the number of panes in the plot.
The CL (calibration) table contains the total model of the interferometer at each interval. Many of these logical records are blank in the case of most interferometers but, for the VLBA, these records will contain essential information. The CL table contains a logical record for each antenna in the array at each CL time stamp. The CL time stamps are set by the user when loading the data. The default for VLA data is every 5 minutes. For VLBI data, it is every 1 minute. Each CL logical record requires
Since most other files are considerably smaller, their sizes can be ignored. That they exist and may require some disk, should not be forgotten. To look at the full disk usage on your computer in summary form:
> USERID 32000 C R
to look at all user numbers.
Then to look at file sizes in detail: