WFC Linearity

We measured recently the linearity properties of the 4 CCDs of WFC. We performed two tests using dome flat light, in fast and slow readout mode. The first test uses data taken on 11 Aug 2011 by Ian Skillen in fast mode up to 60,000 ADU. The second test uses data taken on 29 Aug 2011 by Ovidiu Vaduvescu in slow mode with dimmer flat lights (in order to check the stability of the flat lamp) up to 40,000 ADU. We present the results in the following plots.

In slow mode, WFC is linear within 1% up to 40,000 counts.
In fast mode, WFC is linear within 1% up to 25,000 counts and to 2% up to 60,000 counts.
There is not much apparent difference between the 4 CCDs in both fast and slow readout mode.

WFC LINEARITY PLOTS:

WFC fast readout (click to enlarge):

CCD1	CCD2	CCD3	CCD4

WFC slow readout (click to enlarge):

CCD1	CCD2	CCD3	CCD4

Some old and mostly outdated CASU references (1998-2004) about the WFC linearity and other information can be found here.