July 26, 2006
ALMA Pointing
23
ALMA Prototype Antenna Performance Summary
VertexRSI
AEC
(15,21,32) mm*
(15,18,30) mm*
15/20 mm (non-repeatable/repeatable)
Path Length Stability
1.5-1.8 sec
1.4-1.8 sec
1.5 degree move in 1.5 seconds; settle to 3 arcsec peak
pointing error
Fast Switching
0.3-1.1 arcsec*
0.3-0.8 arcsec*
0.6 arcsec over 2 degree radius
Offset Pointing
1.3-1.8 arcsec*
2.0-2.6 arcsec*
2 arcsec all-sky
Absolute Pointing
16±5 mm
17±5 mm
25 mm RMS (20
mm goal)
Surface Accuracy
Performance
Specification
Property
* Without metrology
** Dt < (3,10,30) minutes