July 26, 2006
ALMA Pointing
20
Accelerometer Measurements
of BUS Pointing Errors
0.07
0.14
900
En
coder Error
0.
23
±
0.0
1
0.8
±
0.5
1
Mosaicking at 0.05 deg/s
AEC
a
(arcsec)
VertexRSI
a
(arcsec)
0.
50
±
0.
03
1.70
±
0.
07
1
OTF at 0.5 deg/s
0.
50
±
0.
13
±
0.
11
±
0.0
2
0.
94
±
0.2
6
±
0.20
±
0
.05
900
Tracking With Wind
0.
29
±
0.
09
±
0.
05
0.
58
±
0.
15
±
0.
08
10
Tracking With Wind
0.
22
±
0.
08
0.
47
±
0.
11
10
Sidereal Tracking (no wind)
0.
45
±
0.
10
±
0.
11
±
0.0
2
0.81
±
0.24
±
0.20
±
0.05
900
Stationary Pointing (9 m/s wind)
D
t
(sec)
Measurement Condition
a
Contributions to each quoted value are defined, respectively, as pointing
Variation, spread, wind power spectrum
uncertainty, and wind extrapolarion uncertainty.
Both antennas ended-up with a 13-term pointing model.