The read-out noise is the noise introduced in the data by the read-out
process of CCDs. It is measured from pairs of bias exposures. The rms
scatter of the differences between two bias exposures is computed and
divided by 1#1
The read noise value is stored in the database using the ReadNoise
class. A query using the select method such as the following will
select the most recently created, valid ReadNoise object available for
the given instrument, date and chip:
To derive the read noise using the DPU (for all 32 CCDs of OmegaCAM
simultaneously in this example) you can do the following (again fill in
instrument and date as appropriate):
To derive the read noise on your own machine you can do the following:
1.1.2 Querying
awe> rn = ReadNoise.select(instrument='OMEGACAM', date='2017-10-01', chip='ESO_CCD_#65')
awe> rn.read_noise
1.99976016871049
1.1.3 Deriving the read noise
awe> # Example using distributed processing
awe> dpu.run('ReadNoise', i='OMEGACAM', d='2017-10-01', C=1)
awe> # Example using a Task (single CCD)
awe> task = ReadNoiseTask(instrument='OMEGACAM', date='2017-10-01'
chip='ESO_CCD_#65', commit=1)
awe> task.execute()