Continuity Correction

In order to avoid ``steps'' in the scrunched data, it is advisable to use this option for long-slit spectra (of course this isn't applicable to data such as form fibre arrays where a smooth curve is not to be expected). Select the POLY option in the main menu:

=========< M a i n   M e n u >=========

Look   : Look at values of data cube
Gaus   : Fit Gaussians to line profiles
Soft   : Produce soft-copy plots of diagnostics
Hard   : Produce hard-copy plots of diagnostics
Tols   : Apply tolerances
Disp   : Evaluate dispersion relation
Add    : Add more lines
Poly   : Fit polynomials in X-Sect direction
Exit   : Leave the program
Main Menu [EXIT] - POLY
keep fits with nag errors for poly fitting? [NO]
Weight fits? [YES]
Performing weighted fit

A plot of the sum of the squares of the residuals against order is displayed.

Go onto next plot? [YES]
 S E E K   M E N U

The residuals are plotted against cross-section. When these appear to be due to noise only, answer ``NO'' to leave the loop, and reply with the order required. A plot of the fit over the centres is given, and similar plots are displayed (two to a page) for the remaining lines, but can be suppressed.

Y for next plot;N to stop [YES]
Y for next plot;N to stop [YES]
Y for next plot;N to stop [YES] NO
(ORder) order for polynomial fitting [3] -
Order returned =   3
Further plotting may be suppressed by typing ``N''
Go onto next plot? [YES]
Performing weighted fit
Go onto next plot? [YES]
Performing weighted fit
Go onto next plot? [YES]
Performing weighted fit
Go onto next plot? [YES] NO
Performing weighted fit
Produce hardcopies of line centre & residual plots [NO]

=========< C o n t i n u i t y   F i t s >=========

Accept   : Accept fits
Retry    : Try again
Quit     : Give up
Continuity Fits [ACCEPT] -

The results are now stored and the user returned to the main menu.