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  - 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.
FIGARO A general data reduction system