TIPS-JIM Meeting
16 June 2005, 10am, Auditorium
1.
Attitude Observer Anomaly
Matt Lallo
2.
3.
On-Orbit Test
ACS/SBC P-flats
Newly Formed Imaging
Ralph Bohlin
Andy Fruchter
Techniques Group
Next TIPS Meeting will be held on 21 July 2005.
AttitudeObserverAnomaly
(AOA)on-orbittest10701
PreliminaryResults,16June2005
June2005TIPS,
M.Lallo&TelescopesBranch
TheAnomaly-Description
Since 2002 we’ve detected anomalously high gyro biases
- occur during terminator crossings
- magnitude of the bias has increased steadily
- 4 arcsec/hr after SM3B to a current -40 arcsec/hr
- predominantly seen in V3 translation
- event typically ~5-10 arcsec, beginning abruptly at day/night - night/day transition
This anomalous motion is usually only virtual, being inferred by
integrating the gyro data; once in Fine Lock, the field is held fixed
by the FGSs
However the worsening gyro bias has caused acq/reacq failures in
the past, and despite successful mitigation efforts, it can eventually
again impact the FGSs ability to acquire or re-acquire guidestars.
AOA Working Group (GSFC, STScI, Goodrich) formed late 2004
to pursue this. http://edocs1.hst.nasa.gov/ota/Observer/Observer.htm
TheAnomaly-SomePossibilities
The RSUs are accurately recording a local motion (i.e. equipment
shelf movement with respect to the OTA and rest of vehicle)
There is no motion local to the RSU and they are recording a
vehicle motion. Since there is no drift in science data this would
mean the OTA FOV is shifting and the FGSs are driving the
vehicle to hold the guidestars at fixed FGS XY
There is some problem in the control law involving both RSU and
FGS data
The RSU data is not correct for other reasons
TheTestObjectives
The test was to represent no risk to the vehicle (e.g. no cycling
RSUs)
Test was designed to determine the involvement of the OTA
structure in the AOA. It should answer the question of the
amount of anomalous motion attributable to the OTA
- obtained science data and measured off-axis PSF aberrations
- aberrations will be expressed in terms of Secondary Mirror tilts
& decenters
- magnitude and direction of image shifts resulting from the
calculated SM motions will be compared to the observed motion,
also directly quantified by the test.
TheTestDesign
Orbit 1 - Baseline and to establish known gyro bias
- FGS fine lock on previously used guidestars
- 100 TRANS mode scans with FGS1 on target star known to be single to FGS
(aberration info)
- 50 ACS/HRC custom sub-array exposures in parallel every 90 seconds. Target
known to be single to HRC (aberration and position info)
- 68 NICMOS/NIC1 multi-accum exposures in parallel every 30 seconds for
maximum time coverage (aberration and position info)
- 2 WFPC2/WF3 exposures at the end to better establish roll baseline
Orbit 2 - Measure position drift to directly observe AOA
- Drop to Gyro Track
- FGS POS mode astrometry (position info)
- 48 ACS/HRC exposures every 90 seconds (aberration and position info)
- 5 WFPC2/WF3 exposures to monitor relative roll changes
3
8
2
8.7
12.3
12.3
12.7
10.5
11.2
11.6
12.6
11.4
10.7
11.5
11.8
TheField
12.4
12.5
10.3
10.3
12.3
12.1
12.4
12.5
12.6
12.6
12.4
7.1
7.3
12.5
13.0
11.3
11.1
11.5
12.3
12.6
9.6
12.9
12.4
12.8
12.4
12.3
11.6
12.2
12.9
12.5
12.4
11.1
11.7
12.111.7
12.9
11.8
11.0
13.2
11.4
11.5
12.4
12.6
8.0
11.9
10.8
11.2
12.3 11.1
12.4
10.8
11.4
12.1
13.2
13.4
12.8
9.9
12.2
12.6
11.0
12.5
10.1
9.7
12.5
10.8
11.
14.1
13
11.9
11.9
12.3
12.8
12.8
12.69.3 13.3
14.2 13.4
12.4
13.0
10.8
11.1
8.1
8.9
11.2
13.0
12
12.5
13.4
11.7
11.5
13.9
11.9
12.0
12.6
12.2
12.5
12.1
11.5
12.7
11.9
11.9
12.6
11.5
11.2
12.5
8.8
11.2
9
10
14.0 7.0
12.4
13.2
13.6
12.7 12.1 11.9
12.4 10.7
12.6
14.0
13.9 12.4
11.9
12.3
12.7
13.
13.5
13.8
13.2
14.0
7.8
6.8 13.1
7.8
12.6
1
13.2
12.6
10.4
11.6
10.5
10.7
11.3
11.6
8.9
12.5
13.3
12.7
11.6
12.7
13.0
12.1
12.5
11.9
11.5
13.0
11.1
12.4
12.0
13.0
12.6
10.
11.1
9.8 11.0
6.2
10.6
12.7
11.5
12.4
12.4
8.9
12.7
10.9
12.0
11.4
9.8
9.7
11.0
10.7
12.4
9.9
9.4
12.1
11.0
7.8
7.7
8.4
8.5
11.5
10.8
10.9
11.3
12.2
11.9 10.4
12.2
10.8
12.612.4
12.8
10.9
10.1
12.5
8.0
8.8
13.9
13.3
12.5
13.5
11.9
11.412.7
11.9
12.1
11.7
13.4
7.5
6.8
7.4
12.3
8.813.3
10.8
11.4
10.4
13.9
12.1
11.6
11.0
12.3
7.9
8.210.9
9.5
9.5
12.6
9.6 10.3
11.0
11.112.8
12.9
12.3
12.7
12.0
12.6
12.9
13.0
9.3
12.5 11.4
11.1
11.5
11.4
11.2
12.3
13.0
12.9
12.1
12.3
12.6
11.3
10.0
9.6
11.3
11.3
9.2
8.8
9.2
11.1
9.5
9.4
9.8
12.6
12.8
10.4
12.7
9.3 12.8
9.4
10.6
MeasuredMotions
Observed Motion of Target in HRC during gyro-guiding Orbit 2
750
700
HRC Y pixels (0.025 arcsec/pix)
650
V3
600
-V2
550
500
450
400
350
350
400
450
500
550
600
HRC X pixels (0.028 arcsec/pix)
Movie courtesy E. Bergeron & M. Reinhart
650
700
750
MeasuredMotions
Observed Motion of Target in HRC & WFPC2/WF3 during gyro-guiding Orbit 2
5.0
arcseconds displacement
3.0
2.0
Day entry
Night entry
4.0
1.0
0.0
V2
V3
V2
V3
-1.0
from
from
from
from
HRC
HRC
WF3
WF3
-2.0
-3.0
-4.0
18.8
18.9
19.0
19.1
19.2
19.3
19.4
19.5
19.6
Day 142 hours
19.7
19.8
19.9
20.0
20.1
20.2
MeasuredZernikes-Focus
ACS/HRC ACS/HRC
AOA Test: Focus
Measurements
& Lightshield Breathing Model
AOA Test:
Focus Measurements
-0.50
Focus
Focus (in
(in microns
microns @
@ Secondary
Secondary Mirror)
Mirror)
Focus (in microns @ Secondary Mirror)
-1.00
-1.50
-2.00
-2.50
0.00
0.00
-0.50
-0.50
Day entry
0.00
ACS/HRC AOA Test: Focus Measurements & Lightshield Breathing Model
-1.00
-1.00
-1.50
-1.50
-2.00
-2.00
-2.50
-2.50
-3.00
-3.00
-3.00
-3.50
-3.50
-3.50
-4.00
-4.00
-4.00
-4.50
-4.50
-4.50 AOA
-5.00
-5.00
-5.00
0.00
AOA
Test 1)
(Orbit 1)
Test
(Orbit
AOA
Test (Orbit
1)
AOA
Test
(Orbit
2)
AOA Test (Orbit 2)
AOA Test (Orbit 2)
Breathing
Breathing
Model Model
17.00 0.10
17.25
17.25
17.00
17.50
17.75 0.30
18.00
0.20 17.75
17.50
18.00
18.25
18.50 0.50
18.75
0.40 18.50
18.25
18.75
19.00
19.25 0.70
19.50
0.60 19.25
19.00
19.50
Orbital Phase
( 0(Day
= night
entry)
Hours
2005.142)
Hours (Day 2005.142)
19.75
20.00 0.9020.25
0.80 20.00
19.75
20.25
20.50
1.00
20.50
MeasuredZernikes-Aberrations
ACS/HRC AOA Test: Y-Coma v. Time
0.003
-0.001
0.002
-0.002
0.001
-0.003
0.000
-0.004
-0.001
Y-Coma
X-Coma
ACS/HRC AOA Test: X-Coma v. Time
0.000
-0.005
-0.002
-0.006
-0.003
-0.007
-0.004
-0.005
-0.008
-0.009
-0.010
17.00
AOA Test (Orbit 1)
AOA Test (Orbit 2)
17.25
17.50
17.75
AOA Test (Orbit 1)
AOA Test (Orbit 2)
-0.006
18.00
18.25
18.50
18.75
19.00
19.25
19.50
19.75
20.00
20.25
-0.007
17.00
20.50
17.25
17.50
17.75
18.00
18.25
0.012
0.011
0.011
0.010
0.010
0.009
0.009
0.008
0.008
0.007
0.007
0.006
0.006
0.005
0.005
0.004
0.003
0.002
0.001
19.25
19.50
19.75
20.00
20.25
20.50
19.50
19.75
20.00
20.25
20.50
AOA Test (Orbit 1)
AOA Test (Orbit 2)
0.004
0.003
0.002
0.001
0.000
0.000
-0.001
-0.001
-0.002
-0.002
-0.003
AOA Test (Orbit 1)
AOA Test (Orbit 2)
-0.004
-0.005
-0.006
17.00
19.00
ACS/HRC AOA Test: Y-Astigmatism v. Time
Y-Astigmatism
X-Astigmatism
ACS/HRC AOA Test: X-Astigmatism v. Time
0.012
-0.004
18.75
Hours (Day 2005.142)
Hours (Day 2005.142)
-0.003
18.50
-0.005
17.25
17.50
17.75
18.00
18.25
18.50
18.75
19.00
Hours (Day 2005.142)
19.25
19.50
19.75
20.00
20.25
20.50
-0.006
17.00
17.25
17.50
17.75
18.00
18.25
18.50
18.75
19.00
Hours (Day 2005.142)
19.25
MeasuredZernikes-Aberrationswithphase
ACS/HRC AOA Test: Y-Coma v. Orbital Phase
Day entry
0.003
0.002
0.001
-0.001
-0.002
-0.003
-0.004
-0.005
AOA Test (Orbit 1)
AOA Test (Orbit 2)
-0.006
ACS/HRC AOA Test: 0o Astigmatism v. Orbital Phase
0.012
0.20
0.30
0.40
0.50
0.60
0.70
0.011
0.80
Orbital Phase (0 = night entry)
0.90
1.00
0.010
0.009
0.008
0.007
0.006
0.005
0.004
0.003
0.002
0.001
0.000
-0.001
-0.002
-0.003
-0.004
-0.005
AOA Test (Orbit 1)
AOA Test (Orbit 2)
0.012
0.011
0.01
0.009
-0.006
0.00
0.008
0.007
0.10
0.20
0.30
0.40
0.50
0.60
Orbital Phase (0 = night entry)
0.70
0.80
0.90
1.00
0.006
./!+,0123,0+2
0.10
Day entry
-0.007
0.00
0o-Astigmatism (in microns)
Y-Coma (in microns)
0.000
0.005
0.004
0.003
0.002
0.001
0
-0.001
-0.002
-0.003
-0.004
-0.005
-0.006
-0.022
-0.023
-0.024
-0.025
UpcomingWork
Optical modeling will back out Secondary Mirror movements like
tilt and decenter needed to produce the observed coma and
astigmatism at the off-axis ACS/HRC (and secondarily, at
NICMOS/NIC1). From these tilts and decenters over time, the
resulting image motion will be derived and compared with
observed to tell us the OTA’s role in the anomaly
FHST maps (also taken throughout the test) are being processed
for maximum spatial resolution and can provide additional
information. They are mounted to the same local shelf as the
RSUs
More reporting to come
0.012
0.011
0.01
0.009
0.008
0.007
./!+,0123,0+2
0.006
0.005
0.004
0.003
0.002
0.001
0
-0.001
-0.002
-0.003
-0.004
-0.005
-0.006
-0.022
-0.023
-0.024
-0.025
TIPS-JIM Meeting
16 June 2005, 10am, Auditorium
1.
Attitude Observer Anomaly
Matt Lallo
2.
3.
On-Orbit Test
ACS/SBC P-flats
Newly Formed Imaging
Ralph Bohlin
Andy Fruchter
Techniques Group
Next TIPS Meeting will be held on 21 July 2005.
ACS HRC
F475W POL0V
P-flat rms(%)= 0.99 0.22 0.96
0.900
1.050
lphe01306sm02f475wpol0v-aft
Bohlin: prtimg 14-Jun-2005 11:56
ACS SBC P Flat
F125LP N/A
P-flat rms(%)= 7.38 0.00 0.00
0.900
1.050
7135
Bohlin: prtimg 14-Jun-2005 14:12
1.20•10
4
Row 200 SBC P-flat
Counts
1.15•104
1.10•104
1.05•104
1.00•104
0
200
400 600
X-pixel
800 1000
ACS SBC P Flat
ANY N/A
P-flat rms(%)= 5.45 0.92 5.38
0.900
1.050
psbcintsm37f125lp
Bohlin: prtimg 14-Jun-2005 15:59
Cycle 14 Proposal for ACS SBC Internal Lamp Usage
For delta L-flats between filters, 6 internal orbits:
F115LP, F125LP, F140LP,
F150LP, F165LP, F122M at 2500s each for total of
For new Prism P-flats with S/N=100 per pixel, 34 internal orbits:
PR110L & PR130L at ~12 hours each for a total of
4.1 hours
23.6 hours
After the additional 28 hours of lamp burn time, ~67% of the lamp lifetime
will remain after 4.5 years on-orbit.
TIPS-JIM Meeting
16 June 2005, 10am, Auditorium
1.
Attitude Observer Anomaly
Matt Lallo
2.
3.
On-Orbit Test
ACS/SBC P-flats
Newly Formed Imaging
Ralph Bohlin
Andy Fruchter
Techniques Group
Next TIPS Meeting will be held on 21 July 2005.
Imaging Techniques
Working Group
Andy Fruchter
What and Who
Intended to assist in the development of
imaging techniques likely to be of wide benefit
to the Institute and its users
Open to all
To join, send email to majordomo@stsci.edu
with the message subscribe itwg
Pixel-based CTE
Correction
A reasonable algorithm already exists to
correct stellar photometry
But how does one handle spectra?
Remove CTE from weak lensing?
Correct astrometry?
Two Approaches will be
Used:
Approximate CTE with a multi-parameter model
based on detailed physics of detector (Bristow
code).
Attempt a more empirical approach starting
with a small number of traps
Trap Parameters
Parameters of Traps used in
simulation of CTE effects for
STIS CCD
(STIS-CE ISR 2002-01, P. Bristow)
ISWG presentation
May 31, 2005
Paul Goudfrooij
7
A Simple Model of Trapping/Detrapping
traps
traps
traps
Assume:
• fixed traps_per_pixel
• Pt=trap probability/transfer
• Pd=detrap probability/transfer
• npix=npixels
Create a fake Image
• Sources of variable flux, at variable positions
• background
Read out charge
• Each clocking step: transfer charge, subtract trapped
charge, add detrapped charge
Drizzle is not Perfect :-(
Relative photometry is very stable -- but
aperture correction depends on Drizzle
parameters
Exact PSF depends not only on parameters but
also sub-pixel phase of input pixels
Noise in output image is correlated
Drizzle++
Drizzle can be used to iteratively approach true
band-limited signal
Final image has (nearly) the statistical power of
Drizzle without the artifacts
The
Result
WFPC2 + Noise
Excited? Enthused?
Merely Curious?
To join, send email to majordomo@stsci.edu with
the message subscribe itwg
Have a look at past presentations at http://
www.stsci.edu/~fruchter/itwg
Next meeting, Tuesday, 21 June: Discussion of
CTE with Paul Bristow
TIPS-JIM Meeting
16 June 2005, 10am, Auditorium
1.
Attitude Observer Anomaly
Matt Lallo
2.
3.
On-Orbit Test
ACS/SBC P-flats
Newly Formed Imaging
Ralph Bohlin
Andy Fruchter
Techniques Group
Next TIPS Meeting will be held on 21 July 2005.