1. One-Gyro Operations FGS Observations
Tips
Feb 21, 2008
Ed Nelan

2. One Gyro Science - FGS
One-Gyro test included 5 orbits of FGS “astrometry”
FGS2r & FGS3 guided
FGS1r observed a bright star in POS mode for the duration of the orbit.
provides an independent check of PCS performance.
One of the orbits used FGS2r in “single guide star” mode (no roll star).
This orbit used two targets in FGS1r to detect roll changes.
Merle Reinhart scripted the phase2 proposal (11078).

3. One Gyro Science - FGS: guide stars
visit
Dom GS
mag
Sub GS 01
NABC000295F3
13.0
NABC000109F2
13.9 02
NABC000350F3
13.7
NABC000137F2
14.19 03
NABC000112F2
14.0 04
NABC000146F2
13.3
none
----- 06
NABC000038F3
14.2
N7IF000091F2
12.9

4. Visit 01
V=13.9
V=13.0
Upgren69
V=9.6

5. Visit 02
V=14.2
Upgren69
V=9.6
V=13.7

6. Visit 03
V=14.0
Upgren69
V=9.6
V=13.7

7. Visit 04
star1
V=9.6
guide star
V=13.3
Star2
V=13.1

8. Visit 6
V=14.2
star1
V=9.6
V=12.9

9. One Gyro Science: observed jitter in FGS1r
visit
Dom GS
mag
Sub GS
X* (mas)
Y* (mas) 01 F3
13.0 F2
13.9
2.6
4.7 02
13.7
14.2
3.2
3.9 03
14.0
2.8
4.2 04
13.3
none
-----
2.3
3.3 06
12.9
3.1
3.4
* This is the standard deviation of the FGS1r centroids

10. One Gyro Mode: astrometry summary
FGS1r observations under 1-gyro mode suggests that PCS performance is not degraded relative to 2-gyro (or 3-gyro) operations.
Visit 04 (single guider) did not exhibit any roll changes greater than what is observed under single guider in 2-gyro & 3-gyro operations.
Single FGS guiding appears to be “fine” in 1-gyro operations.
There appears to be no reason to avoid using faint guide stars (V~14) in 1-gyro operations.