July 26, 2006
ALMA Pointing
6
Optical Pointing Telescope
±
NRAO Design
±
4-inch Refractor
±
IR (
l
> 700nm)
and
clear focus correction
filters
±
Rolled-Invar Tube
±
COTS CCD/Frame
Grabber
±
EPS = 1.1 arcsec per
pixel
±
FOV = 12x9 arcmin
±
Sensitivity > 7th mag in
5 second exposure
¥
Designed and built by Antenna Group in Tucson.
¥
Based on OPT used on NRAO 12m.
¥
Minor problems were:
¥
Focus shift with temperature change.
Likely from lens cell.
¥
CCD nonuniformities.
Confused peak finding algorithm.
¥
Analog CCD output.
Digital less complicated.