Plot
? |
Symb
? |
Source
* |
OPS?
** |
Average ? |
Thresholds ? |
N_
data |
QC1
parameter |
Data
downloads |
Remarks |
| method |
value |
unit |
method |
value |
| 1 |
• | QC1DB |
no |
none |
|
ADU |
none | |
121 |
mean_signal |
this |
last_yr |
all
|
new CCD (after 2008-04): mean image flat value in ADU, as function of exposure time |
| 1 |
o | QC1DB |
no |
none |
|
ADU |
none | |
31 |
mean_signal |
this |
last_yr |
all
|
old CCD (before 2008-04): mean image flat value in ADU, as function of exposure time |
| 2 |
• | QC1DB |
no |
MEAN |
2.2965 |
ADU/el |
3SIG | ± 0.06114 |
24 |
conad |
this |
last_yr |
all
|
new CCD (after 2008-04): GAIN*, from image flats with exptime < 10 sec |
| 2 |
o | QC1DB |
no |
none |
|
ADU/el |
none | |
12 |
conad |
this |
last_yr |
all
|
old CCD (before 2008-04): GAIN*, from image flats with exptime > 60 sec |
| 3 |
• | QC1DB |
no |
none |
|
ADU |
none | |
115 |
median_dit |
this |
last_yr |
all
|
values from plot1, normalized by exptime (only for new CCD) |
| 4 |
• | QC1DB |
no |
none |
|
ADU |
none | |
116 |
conad |
this |
last_yr |
all
|
values from plot2 (any exptime; only for new CCD)
(*note: the QC1 parameter is called conad by mistake, it should read gain) |
| |
|
*Data sources: QC1DB: QC1 database; LOCAL: local text file | **OPS: to indicate that OPSLOG data are included
|
This plot
This is the trending plot for the monitoring of the GIRAFFE
linearity and GAIN, derived from image flats. These data are taken
about monthly.
Note the CCD change between 2008-03 and 2008-05 which required a change in
plot scales and content.
A sequence of image flats is exposed
between 0.5 and 220 secs. Their average exposure level is plotted against the
exposure time (box 1). The fitted function corresponds to
mean = 245*exptime for the old CCD, and 195*exptime for the new CCD. In box 3,
non-linear residuals are plotted vs. exposure time (new CCD only).
The gain (in electrons per ADU) is
also monitored here, as box 2. It is measured from
the difference between two identical raw frames, by comparing the square root
of the signal to its measured rms. The mean GAIN value is indicated in the plot.
PLot 4 (for the new CCD only) shows the GAIN values plotted over exposure
time. The asymptotic value for texp -> 0 is the true GAIN. The value stored in
the file headers is indicated as "nominal".
General information
Click on any of the plots to see a close-up version.
The latest date is indicated on top of the plot, data points belonging to that date are specially marked.
If configured,
- 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
|
