Effective 10 August 2010, we can offer binning 
in all 4 WFC chips and windowing in chip 4 only. 

WFC BINNING:

WFC binning can be set with the following command: 

SYS > bin 1 1  (1x1 pixels, no binnig, by default)
SYS > bin 2 2  (2x2 pixels, pixel scale 0.66")
SYS > bin 1 1  (3x3 pixels, pixel scale 1.0 ")

Following some bias tests to probe the noise in 
binning modes 2x2 and 3x3, we found some differences 
between no binning and binning in the sense that chips 
1+4 have similar noise (binning versus not binning), 
while chips 2+3 present higher noise used in binning 
modes (about 2-5 times higher) than used without binning. 
Probably this effect is due to electronics (WFC uses two 
amplifiers) which we could not investigate yet. 

Regarding reading time for the whole 4 CCD mosaic
measured in slow and fast readout modes, we measured 
the following times: 

bin 1x1 - 48 sec slow mode (28 sec fast mode)
bin 2x2 - 25 sec slow mode (15 sec fast mode)
bin 3x3 - 15 sec slow mode ( 8 sec fast mode)


WFC WINDOWING:

WFC windowing is possible only in chip 4. 
To set binning window [X1:X2,Y1:Y2] (with X and Y 
coordinates to cover the necessary region (CCD 
coordinates of chip #4) around the object, type: 

sys> window 4 '[X1:X2,Y1:Y2]'

to disable this window, type:

sys> window 4 disable

Once again, CCD #4 is the only chip that can be windowed.

Moreover, one can define four different windows at 
the same time on CCD #4 (provided they do not overlap), 
namely window 1, window 2, window 3 and window 4. 
Remember, these are not related with the four chips. 


Contact: 
Ovidiu Vaduvescu (ovidiuv@ing.iac.es)
Andrew Cardwell  (cardwell@ing.iac.es)
Pablo Rodgriguez Gil (prguez@ing.iac.es)