MCCLASS / COLORS

Purpose:

Calculation of colour indices and their errors for an object table, using the flux data :_F_$$$$ und their errors :sFc$$$$. These colour indices are also used for the calibration tests with the stellar main sequence using MCCLASS/MAINSEQ and for the classification with MCCLASS/CLASSIFY. For COMBO-17 usage, see particulars below.



Syntax:		MCCLASS/COLORS  [flux-table]  

	   	   flux-table = Name of object table
				(no default)



Example:	MCCLASS/COLORS  flux16h_Dec00.tbl
Remarks:

Colour indices are in units of CD magnitudes. The CD magnitude is defined as CDmag = -2.5 * log10(F phot) - const. The AB magnitude contains F nue as an argument for the logarithm and the ST-Magnitude has F lambda. As a result, the CD magnitude is always the mean of AB and ST magnitude. These three magnitudes are physical definitions. Astronomical magnitudes have the ratio of object flux and Vega flux as an argument of the logarithm. All magnitude systems are calibrated such, that Vega has ABmag = CDmag = STmag = mag = ... = 0.0 at 548 nm wavelength. The CADIS filter set has the following colour indices, e.g.: 
:bmr		
:rmi	
:imk	
		
:bmb489		:v396mb
:b531mr		:bmv465	
:b612mr		:v522mr
:rmb700		:v535mr
:b752mi		:v611mr
:imb855		:v628mr
:imb909		:rmv683
		:rmv702
The column names of the colour indices are always constructed along the same scheme. They are denoted :{bluer filter}m{redder filter}.


COMBO-17 use:

In COMBO-17 every survey field needs its own colour-calculating prg to allow for good variability correction in the survey, which is essential for high-quality photometric redshifts of QSOs. The respective commands for the fields are collected in the directory MCC and are:

  • @@ MCC:mc_colors_A901
  • @@ MCC:mc_colors_A901_Asinh
  • @@ MCC:mc_colors_AXAF
  • @@ MCC:mc_colors_AXAF_Asinh
  • @@ MCC:mc_colors_FDF
  • @@ MCC:mc_colors_S11
  • @@ MCC:mc_colors_S11_Asinh
The *Asinh.prg versions are to be used for a new classification due in summer 2005, while the other versions are the basis of the commonly used catalogues in the J2003 series.



Back to COMBO-17 index page

Last update July 19, 2005, CW