column name 
parameter 
content 
ORDER 
order number 
counting from 1 to N where N is the maximum number 
I_CH 
index of chunk 
for each order, parameters are evaluated at certain
X positions (chunk; typically 50100) 
X_CH_0 
X position of chunk 
X position in px 

P_CH 
Y position of signal in chunk 
measured Y position of the maximum in the signal
as found by the optimum extraction routine 
P_ERR0 
variance of Y position 
error related to P_CH 
P_F0 
Y position of signal after first fit 
A 2nd order polynomial is fitted to the P_CH values
where all values with an error above a threshold (2 sigma rms) are
excluded. 
P_F1 
Y position of signal after second fit 
A kappasigma routine is used to clean the positions
P_CH from outliers with high weight factors (low P_ERR0 but outlier
in P_CH). Then a final 2nd order polynomial fit is performed. The
:P_F1 values are then used to extract the signal. 
M_0 
mask value (0 or 1) 
mask value before first fit (1 is good) 
M_1 
mask value (0 or 1) 
mask value before last fit (1 is good) 

P_FWHM 
crossdispersion width of signal 
measured crossdispersion width per chunk (these
values are obtained by fitting a Gaussian to the signal profile but
they are measured in the sense that they are independent of each other) 
P_FWHM_ERR 
variance of FWHM 
error related to P_FWHM 
S_CH_0 
width of signal after first fit 
A 2nd order polynomial is fitted to the P_FWHM values
where all values with an error above a threshold (2 sigma rms) are
excluded. 
S_CH_1 
width of signal after final fit 
A kappasigma routine is used to clean the FWHM
values from outliers with high weight factors (small errors). 

BKGVAL 
background value of fit 
background value (linear offset) used to obtain
the fit; this number contains any contribution to the background like
sky, scattered light, extended emission. It is usually dominated by
sky emission, especially in case of moon light background. BIAS is
not included here (it has been removed prior). 
BKGERR 
error of BKGVAL 
associated error 