Manually setting the exposure time

The flux calibration process requires the exposure time of the observation being calibrated. This datum is stored in a standard location in the NDF file holding the spectrum. If your data originates from one of the usual sources, such as the AAT or UKIRT, then the exposure time will probably already be in the correct place in the data structure. However, if your data came from an unusual source then the exposure time may either be present in an unusual location or absent altogether. In these cases you will need to manually add the exposure time to the NDF. The item that has to be added is:

   MORE.FIGARO.TIME

It should be of type _REAL and expressed in units of seconds. Figaro applications `creobj' and `setobj' can be used to respectively create and set the exposure time. E.g. if your data file was called `myobs.sdf' and you wanted to set an exposure time of 90 seconds then you would type:

   ICL> creobj type=_REAL dims=0 object=myobs.MORE.FIGARO.TIME
   ICL> setobj value=90.0 object=myobs.MORE.FIGARO.TIME

If the structures `MORE' and `FIGARO' do not already exist in your data file then you will need to create them before creating the exposure time:

   ICL> creobj type=struct dims=0 object=myobs.MORE
   ICL> creobj type=struct dims=0 object=myobs.MORE.FIGARO