Keywords: class-herschel-fits

Next: Setting the source velocity Up: Quick start guide Previous: Observation header Contents

## Associated Arrays

The spectra imported from Herschel-HIFI FITS are also one of the firsts to use the so-called Associated Arrays in the CLASS observation. These arrays can be found under the structure `R%ASSOC%`. CLASS can understand those special arrays (see below where the dedicated documentation can be found). In practice, the Herschel-HIFI spectra provides the usual intensity array (i.e. in the `RY` variable), but also 2 arrays of the same size (same number of channels):

- the `BLANKED` Associated Array is an integer flag array indicating if the `RY` values should be blanked out (1) or not (0), under the user choice. This array is similar the usual bad values in CLASS, except that the actual values (i.e. before blanking) are still available. The typical use of this array is:

        LAS> LET RY R%HEAD%SPE%BAD /WHERE R%ASSOC%BLANKED%DATA.EQ.1

- the `LINE` Associated Array is an integer flag indicating if the `RY` values are in (1) or out (0) a spectral line window. If the option `/ASSOCIATED` is invoked with `SET WINDOW`, the command `BASE` will use this array (i.e. ignore channels in a spectral window) for baselining (see `HELP SET WINDOW` for details). Typical use is:

        LAS> SET WINDOW /ASSOCIATED  ! Will use the LINE Associated Array
        LAS> SHOW WINDOW             ! Check you will use the LINE Associated Array
        LAS> DRAW WINDOW             ! Draw the LINE Associated Array on the spectrum
        LAS> BASE                    ! Use the LINE Associated Array during baselining

Note that the Associated Arrays are removed by the commands that do not know how to process them. In this case, a warning is issued. This is being solved as the Associated Arrays are more and more integrated in CLASS. In order to know the current status, please check the dedicated documentation for your current CLASS version in the widget menu Help CLASS Associated Arrays.

Next: Setting the source velocity Up: Quick start guide Previous: Observation header Contents