UVIS and NAC Boresights
Relative to SRU-A
1.200
HSP
-Z Axis
1.200
.200
.570 NAC
.170
.100
+X Axis
FUV
1.200
EUV
1.300
Instrument Boresights Relative to Spacecraft SRU-A (mRad)
8/22/02
EUV
FUV
HSP
NAC
X Axis
1.2
0.2
1.2
0.576
Z Axis
1.3
0.1
-1.2
-0.171
UVIS Stellar Pointing Summary
Date
6/2/2000
6/21/2000
10/2/2000
4/3/2001
5/29/2001
10/30/2001
Target
Spacecraft AACS
Location (mRad
Relative to
SRUA)
X Axis Z Axis
EUV Channel
Location (mRad)
Hi Res
Slit
Lo Res
Slit
FUV Channel
Location (mRad)
Hi Res
Slit
Lo Res
Slit
NAC
Boresignt
Alp Psa II
(1)
Alp Psa II
(2)
0.63
0.13
0.57
0.14
Z=0
Z=0
0.61
0.10
Missed
Z=0
NAC
Boresight
Alp Vir II
Eps Cma I
Alp Vir III
0.57
-0.17
0.56
0.57
0.56
-0.28
-0.13
-0.28
No Data
Z=-0.25
Z=-0.23
Z=-0.24
Missed
Z=-1.48
Z=-1.47
Z=-1.48
Spacecraft AACS locations were calculated using a web-based spacecraft point tool: http://wwwpw.physics.uiowa.edu/~tfa/cassini.html.
The spacecraft pointing is adjusted to place the target on the NAC boresight. The first Alpha Psa
observation was located in line 510.1 and sample 561.9; therefore, the NAC boresight was
changed by -0.006 in X and –0.302 in Z for subsequent observations.
The X-axis boresight for the FUV from the ICO Spica observation was 0.1 mRad. At least part
of every observation with the Hi Resolution FUV slit is successful, implying that the FUV Xaxis boresigt is ~ 0.57 -0.375 = 0.195 ~ 0.2 mRad.
The X-axis boresignt for the EUV from the ICO Spica observation was 1.2 mRad. This is
consistent with the laboratory calibration, which showed that the EUV and FUV boresights are
displaced by ~1 mRad.
8/22/02