| |
| QC PLOTS |
| |
CURRENT |
HISTORY |
| FF
level: |
|
|
| FF
saturation: |
|
|
|
|
Click on CURRENT to see the current trending (Health Check).
Click on HISTORY to see the historical evolution of the trending. |
In addition to the fibre localization information, the flat field
calibrations are taken in order to register the gain variations of the CCD (pixel
to pixel, or fixed-pattern noise), fringing, and the fibre-to-fibre sensitivity variations.
To properly record these properties, it is important to monitor the level of the
flat field exposures, and avoid underexposure as well as saturation.
| top Exposure
level (robotic flat field) |
The exposure level obtained by the robotic flat-field lamp is routinely
monitored in a pattern involving the L543.1 setup in every slit system ("HC settings").
A single flat frame is measured. The mean exposure level of the raw file is measured
(including the fibre signal and the inter-fibre signal), trended and scored. Thresholds
are defined to detect underexposure or overexposure.
While the FFLEVEL plots monitor these standard setups regularly, the
mean exposure level in all fibre flats is evaluated in a similar way in the
FFLEVEL_ALL plots, but with the scoring thresholds being less sensitive since they
cannot be fine-tuned for every single setting.
Finally, the FFLEVEL_WLN plot records the mean exposure level over
wavelength.
QC1 parameters
| parameter |
QC1 database: table, name |
procedure |
| mean signal |
giraffe_flat..mean_raw |
measured across whole frame, in ADU |
Trending
Panels of the trending
plot:
 |
| Boxes 1-2: FF exposure level. Data are from HC calibrations
in the L543 setup, for Medusa1 and 2. The boxes 4-6 contain similar data for IFU1,
IFU2 and Argus. |
Plots of spectrally resolved relative fibre transmission can be found
here.
| topSaturation
(robotic flat-field) |
A saturated flat field can still be used for localization of the fibre signal (unless
in extreme cases), but the information related to pixel-to-pixel gain variations, to
fringing and to fibre-to-fibre sensitivity is lost in the saturated regions. Therefore
all measured flats are monitored in terms of saturated pixels.
QC1 parameters
| parameter |
QC1 database: table, name |
procedure |
| number of saturated pixels |
giraffe_flat..qc_numsat |
number of pixels with values > 65,000 |
Trending
 |
| Boxes 1 and 2: number of saturated
pixels for Medusa1 and Medusa2. The values are usually 0, a flat with saturation
clearly stands out. |
top
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