These two OBs take extrafocal (Z= -0.8mm) pupil images which are 
used for focus and collimation.

They use the V-BESSEL for Blue and r-SLOAN for Red. The analysis
routine has been optimized for these filters; even if your science
observations will be carried out with different filters, use these
for the pupil images.

RB_rVfastextra.ob and RB_rVfastextra_off.ob both take two 16-sec 
images, one per channel, using a subregion of chip 2. 

The DEC is set to -90 degrees which signals not to slew the telescope; 
use "current" position.  You should slew to your target by loading the 
science OB, and clicking play then stop to slew but not carry out the 
integrations. 

The only difference between these two OBs is that RB_rVfastextra_off.ob 
will offset the telescope before integrating. This may be useful for 
target fields which contain extended or many non-stellar objects. It offsets
10 arcmin N, but this can be changed by editing the RA or DEC dither in the
boxes under "Dithering Offset Steps" on the "Observation Description" page.