|
|
|
QC
PLOTS |
|
CURRENT |
HISTORY |
dark
level |
|
|
RON |
|
|
QC1
database (advanced users): browse
| plot
|
Click on CURRENT
to see the current trending (Health Check).
Click on HISTORY
to see the historical evolution of the trending. |
Dark frames are measured daily as part of the calibration
plan in sets of 3 frames for each DIT value. Darks with DIT = 1 and 300
sec are taken every day as health check. Darks with other DITs are only
measured when they are triggered by settings used during the night.
|
DARK frame. Example
frame for detector #3 with DIT = 1 sec. Detector glow is present
in the corners close to the amplifiers.
|
top
Dark
level and read-out noise |
All QC1 parameters for CRIRES dark exposures are measured
on the central area with x = 256 ... 768 and y = 128 ... 384 for each
detector array separately in order to avoid contamination from the detector
glow.
QC1 parameters
parameter |
QC1 database: table, name
|
procedure |
median dark level |
crires_dark, darkmed |
The median level of each input raw frame is determined;
the QC parameter is the average of the three values. |
read-out noise (RON) |
crires_dark, ron12
crires_dark, ron23 |
The difference of the second and first (RON1) and
of the third and second (RON2) input frame is calculated. The read-out noise is calculated from the difference image as follows:
- generate 100 13x13 pixel windows
- compute the pixel standard deviation in each window
- the read-out noise is the median of these measurements multiplied with sqrt(NDIT/2).
RON2 is the more reliable determination. |
standard deviation |
crires_dark, dark_stddev |
This is the standard deviation of the median levels
of the three input frames. |
Trending
Dark level and read-out noise depend on the DIT. Both
parameters are trended for the daily health check settings with DIT =1
and 300 sec for each detector (chip) separately. For the read-out noise,
the ron23 value is chosen.
History
2010-09: ron on detectors 3 and 4 increased after intervention
2011-04-14: temperature of detectors 3 and 4 adjusted, ron and dark levels back to normal
2011-10-11: ron decreased on detectors 3 and 4 after intervention because of low detector temperatures; fixed on 2011-10-17
|