July 26, 2006
ALMA Pointing
18
ALMA
Core Pointing Model
Az/El non-perpendicularity
DA = +NPAE
tan(E)
-15.01/+28.62
NPAE
Az/El nonperp variation twice per Az rev, cosine
component
DA = -HVCA2 cos(2A) tan(E)
NA/-2.08
HVCA2
Az/El nonperp variation twice per Az rev, sine component
DA = +HVSA2
sin(2A) tan(E)
NA/-2.25
HVSA2
El nod 3X per Az rev, cosine component
DE = +HESA3 cos(3A)
-0.34/NA
HECA3
El nod 3X per Az rev, sine component
DE = +HESA3 sin(3A)
+0.94/NA
HESA3
Az encoder error 3X per rev, sine component
DA = +HASA3 sin(3A)
+0.38/NA
HASA3
El nod twice per Az rev, cosine component
DE = +HECA2 cos(2A)
NA/+1.53
HECA2
El nod twice per Az rev, cosine component
DE = +HESA2
sin(2A)
NA/-0.99
HESA2
Az encoder tilt, cosine component
DA = -HACA2 cos(2A)
NA/+2.94
HACA2
Nominal Cause
Correction Formula
Az encoder tilt, sine component
DA = +HASA2
sin(2A)
+0.73/-1.70
HASA2
Az encoder run-out, cosine component
DA = -HACA cos(A)
-4.42/NA
HACA
Az encoder run-out, sine component
DA = +HASA sin(A)
-1.20/NA
HASA
El encoder run-out, cosine component and/or vertical
flexure
DE = +HECE cos(E)
+30.09/-16.85
HECE
El encoder run-out, sine component
DE = +HESE
sin(E)
NA/-27.56
HESE
Ampl. (V/A)
Term