Nine Detectors Free!

Yes, if you are using the LWS01 or LWS02 AOT, your ISO data will typically contain a sparse sampling of wavelengths across the entire LWS band between 43.0 to 196.7 um, gathered from the "other" nine detectors not selected for the primary part of your specified measurement. This is one of the truly wonderful attributes of the LWS - you can look at a line, detect it, and get a good measurement of the FIR continuum of an object at the same time completely free!

You can calculate the noise at each grating step from the other detectors, approximately, by running the time estimator, lws-te, and seeing how much time is spent at each grating step in your measurement. You can then use the inverse of formula 6.8 of the LWS Observers Manual to compute the noise to expect in a grating step from the other detectors:

Noise = NEFD / [ (2 t ) ^ 1/2 ]

where the NEFD is obtained from table 3 or 6 in the LWS Observer's Manual and the Noise is expressed in units of 10^(-17) W/m^2. One must choose a "sample" NEFD for each detector, since it is impossible to predict beforehand the exact wavelengths which the other detectors will be seeing. Typically you will get mant steps in thes other detectors. If, for example, you have specified an LWS02 observation with a spectral step size of 4 and a scan width of 2, you will have 20 data points (wavelengths) in you line measurement. In each of 9 other detectors, you may have this many data points as well.

Caveat: You are not assured of getting data from all nine detectors, because your observation may be accomplished in a scan mode or an overscan mode that may place the incoming radiation "out of reach" of the wavelength coverage of some of the other nine detectors. Also, it is yet unclear if the same calibration routines that will be applied automatically for you for your specified AOT data will also be applied to the output of the other nine detectors; there may well be further calibration work necessary on the part of the observer to recover this addition data.