The second parameter defines the reference frame. When Reference Frame='N' (for North), the Orientation angle is the standard astronomical Position Angle, measured CCW to the East from celestial North. When Reference Frame='Y', Orientation angle=0 and Map Lines are fixed along the ISO telescope Y-axis. The spacing of points along these Map lines is the "Step Size in M" in arcseconds. The spacing between the Map Lines is the "Step Size in N" in arcseconds.

M and N are integers and may take values between 1 and 32 inclusive. The points are visited in the following order (for a grid of M=4, N=3)

01 02 03 04

08 07 06 05

09 10 11 12

The distance on the sky between points in one line (the M direction) is given by the step size which must be between 0 and 180 arcsecs (in fact, you should not use less than 10 arcsecs to allow the instrument to be synchronised to the telescope movements) In the N direction the step size should be between 2 and 180 arcsecs inclusive. These two values are also integers.

Spectrum Start Wavelength (in microns) - a real value between 43.0 and 196.7

Spectrum End Wavelength (in microns) - a real value between 43.0 and 196.7 This must also be larger than the starting wavelength

Spectral Sampling Interval - expressed as the number of spectral samples per spectral resolution element. The value is an integer (allowed values are 1,2,4,8 with the default value being 4)

Number of exposure values - The exposure values are use to calculate the integration time required to achieve the required signal to noise ratios (or better) at each of the wavelengths given. This is an integer value between 1 and 10

Fast Flag - indicating if individual scans are to be carried out as quickly as possible. This may be required for observing small features on a large continuum. This is a character which may take the values 'y' or 'n'

Expected Wavelength of line - This should be the wavelength after correction for redshifts, etc relative to the solar frame of rest. This is a real value in the range 43.0 to 196.7 microns

Spectral Scan Width - Expressed as the number of spectral resolution elements to scan each side of the expected wavelength for each line. If zero is specified the grating remains at a fixed position during the measurements on the line. This allows an undersampled spectrum to be obtained in a short time. This is an integer value which may be one of the following; 0,2,3,4 for LWS02; 3,4,5 for LWS04.

Spectral Sampling Interval - expressed as the number of spectral samples per spectral resolution element for each line. This is an integer value which may be one of the following; 1,2,4,8. The default value is 4.

Fast Flag - indicating if individual scans are to be carried out as quickly as possible. This may be required for observing weak lines on a large continuum. This is a character value which may be 'y' or 'n'

Continuum Flux - for the object at the line wavelength. This is a real value given in Janskys and must be greater or equal to 0.0 This value may only be set to 0.0 if the Integrated Line Flux is not zero

Integrated Line Flux - for the object at the line wavelength. This is a REAL value, given in W m-2, and must be greater than or equal to 0.0 This value may only be set to 0.0 if the Continuum Flux is not zero.

The width of the line - in the LWS field of view. This is a REAL value, given in microns, whcih must be greater than or equal to 0.0. This parameter is only necessary if the LFLUX value corresponds to a spectrally resolved feature. If not then the value should be set to zero

Required Signal to Noise Ratio - per spectral step for the line. This is a REAL value and must be set to zero if the Required Total Integration TIME is non zero, otherwise the allowed values are >= 1.0

Required Total Integration Time - per spectral step. This is a REAL value, in seconds, and must be set to zero if the Required Signal to Noise Ratio is non zero, otherwise the allowed values are > 0.0