Structure of RO files

Since SCUBA can produce data from more than one sub-instrument simultaneously and yet only one file is wanted for each observation, the RO files are in fact HDS container files containing NDFs. In general there is one NDF for each sub-instrument used plus one NDF containing all the observation parameters (it is a blank NDF containing a FITS extension).

For example, a map observation with the LONG and SHORT wave array would produce an RO file with the following structure:

% hdstrace m97az98_red_0001
M_970308_50  <SCUDR_MAP>

    LONG  <NDF>
        ....image from long-wave array

    SHORT <NDF>
        ....image from short-wave array

    HEADER <NDF>
        ....Observation parameters in FITS extension

The image from the long wave array would be displayed in KAPPA with:

% display clear axes m97az98_red_0001.long

and the FITS information would be displayed with:

% fitslist m97az98_red_0001.header

In addition to one NDF per sub-instrument, there is also one NDF per measurement. For example, the RO file from a FOCUS observation would contain an NDF for each FOCUS position names MEAS_1, MEAS_2 etc. - this is the case for FOCUS and ALIGN observations. Skydip data is slightly different since the names of the NDFs are of the form SUB_WAVELENGTH (i.e. SHORT_450 and LONG_850).

If an observation is only using a particular bolometer (eg a FLATFIELD or PHASE observation) there will be an NDF for the bolometer (eg H7) rather than for the array as a whole.