JSA FAQ: examining data reduction parameters

If you know what hislist and provshow do, you can skip this entry.

Say you have downloaded your most excellent project product from the JSA and you are interested to see what went in it. Here's what you do (assuming, of course, that you have already sourced your Starlink startup files).

Convert the FITS file back to NDF (we'll call the result example for brevity):

 ; convert

; fits2ndf jcmts20100228_00040_850_reduced001_pro_000.fits example

So we now have our example.sdf

To see the history of the file, run the KAPPA hislist (history list) command:

; kappa

; hislist example

In the voluminous output, you will see the full parameters of any command ran on this file, for example, the makemap parameters that were used to generate this SCUBA-2 product:

In order to see what observations went into this product, use the KAPPA provshow (provenance show) command:

; provshow example

which will show you the entire provenance tree for your file.

Thanks to the NDF history and provenance mechanism, every operation on the data files is automatically recorded, so you have a complete record of what was done to the data.