The ideal set of input files for MAKEE would be an object exposure of an isolated, unresolved point source of moderate brightest (V~15-20), a clear trace exposure of a bright, hot star (white dwarf standard such as 300 seconds on Feige 34), a flat field which clearly shows all orders, is not saturated and where there are clear gaps between the orders , and a normal (1-2 second) ThAr arclamp exposure. The slit length should be at least 5 times the PSF of the profile (7 arcsecond slit generally works well).

The setups should not be too blue or too red (range within 3500 to 9000 Angstroms) and the echelle angle should be in a reasonable range (within about -0.7 to +0.7). The setup angles (ECHANGL and XDANGL) between input files should agree closely (within 0.002) (see tolerances ). Assuming the guiding is good (with a gaussian looking PSF) and it is not too cloudy, MAKEE should produce good results.

Even though MAKEE will often produce good results even beyond these limits, this should be a guide as to when problems may occur. For example, good reductions have been made well below 3500 Angstroms and above 9000 Angstroms (although the wavelength accuracy degrades above about 9500). MAKEE has also been able to reduce very faint sources and bright sources (also adequate profile modelling is difficult for very bright sources which can cause pixel rejection problems). Also you may need to compromise between the slit length and the overlap of orders at the blue end of the spectrograph (MAKEE is designed to take care of a small level of order overlap in the blue). Also a faint source or even a quartz lamp with the D5 decker will often work adequately for the trace exposure.

MAKEE has been modified (and is still being modified) to better reduce a wide range of input files, but in general the closer your data is to the ideal case, the better your results.

Back to "MAKEE User Guide" main menu...

(June 2008)