19.7 SCALE_FLUX

[CALIBRATE\]SCALE_FLUX Find|Apply|List|Calibrate [Args...]

A set of commands to check flux calibration on a day to day basis. It gives the ratio between the observed flux (in the current UV data set) and the model flux for each separate period. The Model flux can be derived from Clean Component Tables using the MODEL command, or read from an outer file using READ MODEL.

Error bars are approximate. The User-defined command SOLVE_FLUX performs a more accurate evaluation of the error, but is typically 50 times slower.

SCALE_FLUX FIND [DateTolerance [UVmin UVmax]]
determines, by linear regression, the best scaling factor to match date by date the UV data set with the MODEL data set. Separate Periods are defined when Dates differ more than DateTolerance (default 1 day). Only data with baseline lengths in the range UVmin UVmax are considered for the regression (default all).

SCALE_FLUX APPLY VarName
apply previously determined flux scale factors to the MODEL data set, previously read by READ MODEL. This is in general used only in an iterative search way, e.g. by the user-defined command SOLVE_FLUX (which calls procedure solve_flux). The resulting UV data set is loaded into the specified VarName SIC variable.

SCALE_FLUX LIST
print out dates, baselines and determined flux factors

SCALE_FLUX CALIBRATE
apply previously determined flux scale factors to the current UV data set (i.e. divide the visibilities by the scaling factor of each date, and correct the weight accordingly). This may then be written using command WRITE UV .

SCALE_FLUX SOLVE [DateTolerance [UVmin UVmax]]
combines FIND and PRINT behaviours.