Plot ? 
Symb ? 
Source * 
Average ? 
Thresholds ? 
N_ data 
QC1 parameter 
Data downloads 
Remarks 
method 
value 
unit 
method 
value 
1 
•  QC1DB 
MEDIAN 
0.779 
flux_ratio 
none  
29 
flat_spec_a 
this 
last_yr 
all

current flat / reference flat = a + b * (lam  lam0) 
2 
•  QC1DB 
MEDIAN 
3.9 
1/nm 
none  
29 
flat_spec_b 
this 
last_yr 
all

current flat / reference flat = a + b * (lam  lam0) 

*Data sources: QC1DB: QC1 database; LOCAL: local data source

Plot 1 scores: not implemented
 data source:  xshooter_flat (QC1 database) 
dataset:  flat_spec_a  • 
median:  0.779  flux_ratio 
thresholds:  none  
N_data plotted:  29 
[click plot for closeup] 
Plot 2 scores: not implemented
 data source:  xshooter_flat (QC1 database) 
dataset:  flat_spec_b  • 
median:  3.9  1/nm 
thresholds:  none  
N_data plotted:  29 
[click plot for closeup] 
This plot
This plot monitors XSHOOTER flat field spectra.
For this reason flat field spectra are generated and are
compared to a reference flat field spectrum.
We fit the flat field spectrum via the following linear formular:
current(lambda) = reference(lambda) * ( a + b * ( lambda  lambda_0 )
where lambda_0 is the center wavelength of the considered wavelength range,
parameter a is the relative overall flux of the spectrum, corresponding
to the lamp power and parameter
b is a first order chromatic deviation (the slope between the reference flat spectrum and
current flat spectrum). The reference spectrum is from 20151024.
This plot shows both parameters a and b, of which paramter b is the important one.
On 20151024, there is a=1 and b=0 by definition.
E.g. a = 1.22 means the current flux calibrated flat spectrum is 22%
brighter than the flux calibrated reference spectrum.
A negative b (e.g. b = 1e4) means the spectral slope of the current
spectrum is less steep, hence blueer than the reference spectrum.
In the trending plot, increasing b means the spectrum becomes redder, decreasing b means the spectrum
gets more blue.
General information
Click on any of the plots to see a closeup version.
The latest date is indicated on top of the plot.
If configured,
 data points belonging to the latest date are specially marked
 statistical averages are indicated by a solid line, and thresholds by broken lines
 outliers are marked by a red asterisk. They are defined as data points outside the
threshold lines
 "aliens" (= data points outside the plot Y limits) are marked by a red arrow (↑ or ↓)
 you can download the data for each parameter set if the 'Data downloads' link shows up
