TIPS-JIM Meeting
15 February 2007, 10am, Auditorium
1.
ACS Status Update
Marco Sirianni
2.
Update on NICMOS flat-field monitoring
Tomas Dahlen
3.
Speckle Interferometer for Measurement
Babak Saif
of Large Optical Structures
Next TIPS Meeting will be held on 15 March 2007.
ACS Current Status
M.Sirianni
TIPS Feb 15, 2007
Agenda:
• ACS Side-2 failure
• SBC reactivation
• ACS programs conversion
Timeline:
January 27, 2007
12:29:12 – ACS began WFC observation, shutter was closed because of a
GSACQ failure
12:34:17 – Initial spike in HST structure current
12:34:21 – Begin a 7-second ramp-up of HST structure and load bus current
12:34:28 – ACS PDU-2 fuse blows, ACS telemetry goes to zeros
12:34:33 – ACS suspended because of invalid mode
12:34:37 – NCS pressure sensor detects a pressure burst, initiating HV
protection and NCS safing
12:34:38 – ACS safed because of invalid mode
12:34:42 – HST enters Inertial Hold
January 29 – ACS Hybrid LEI team given “go” to prepare for Side-1 switch pending
ARB recommendation and HST Project approval
January 31 – ACS Side-2 ARB Kickoff Meeting. Goal: “Assess the risks of
recovering SBC Operations on ACS Side-1”
February 5 – ARB Status Briefing #1 to HST Project
February 9 - ACS heater zone B switched to Side-1
February 13 – ARB Status Briefing #2 to HST Project
February 15 - Flight Readiness Review
• HST was recovered from Inertial Hold Safemode DOY 028
– Health and Safety SMS intercept at 028/07:00
– HGA communications restored at 028:07:55
• Safing System is in its Nominal Operational Configuration
– Neon Leak Safemode Test was re-enabled 028/17:45 UT
• Battery performance is nominal
– Battery temperatures are below 0degC since event and converged
– System SOC increased 3-5 A-H
• TPS reporting nominal pressures
• FHSTs and FGSs powered back on
– Temperature and performance are as usual
• NCC was returned to its operate configuration on DOY 030/01:09 UT
• NICMOS was recovered to SAA Operate on 032/15:48 UT
– Subsequent filter wheel checkout was nominal
– Resumed science observations - NGC 4639
• WFPC2 resumed nominal science operations
– Calibration image of Omega Cen, a globular cluster
What was observed:
•
Structure current elevated in two events separated by ~3.5s
– First event persisted for ~1.5s and peaked at ~6A
– Second event persisted for ~7s, increased gradually, was very noisy,
peaked at ~18.6A, and ended abruptly
•
Main Bus current elevated during both events
– First event approximately tracked structure current
– Increase during second event peaked at ~37A
•
•
•
•
PDU-2 current elevated only during second event, increase peaked at
~13.6A
ACS input current monitor saturated at 12A during peak of second
event and returned to zero when event ended
ACS input voltage sagged by ~1.5V during peak of second event and
dropped to zero when next sampled after drop in currents
NCS/ESM Total Pressure Sensor measured peak pressure of 1.0E-4
torr
– Pre-anomaly reading was 1.6E-7
•
After the overcurrent event finished, the gas pressure decreased
exponentially
Possible origin of fault:
1. MEB1- LVPS2 (Side-2)
2. Auxiliary Power Box (APB)
3. Harnesses between LVPS2 and APB
Most likely cause of the fault:
Exploding/burning tantalium capacitor
The ARB is still investigating ways to rule out origin of the fault.
So far the primary goal of the ARB has been the assessment whether
SBC can be safely operated under side-1.
Current Situation
28V
Spacecraft
Input
Power
(PDU)
28V
Spacecraft
Input
Power
(PDU)
ACS
Hold Power 1
Powered
Units
Unpowered
Units
Previously
Failed Unit
Heater Power 1
Hold
Circuits
Side-1
Hold
Circuits
Side-2
Zone A1
Zone A2
Zone B1
Zone B2
TEC Power 1
Hold Power 2
Heater Power 2
TEC Power 2
TEC
CEB Power 1
Anneal Power 1
CEB Power 2
Anneal Htrs
Side-1
CEB
Anneal Htrs
Side-2
Anneal Power
SBC
Operate Power 1
Mechanism
Power 1
MEB
Side-1
Mechanisms
Side-1
MEB
Side-2
Mechanisms
Side-2
Calibration
Power 1
Operate Power 2
Mechanism
Power 2
Calibration
Power 2
Calibration Lamp Controller
Side-1 powered on for SBC Operation
28V
Spacecraft
Input
Power
(PDU)
28V
Spacecraft
Input
Power
(PDU)
ACS
Hold Power 1
Powered
Units
Unpowered
Units
Previously
Failed Unit
Heater Power 1
Hold
Circuits
Side-1
Hold
Circuits
Side-2
Zone A1
Zone A2
Zone B1
Zone B2
TEC Power 1
Hold Power 2
Heater Power 2
TEC Power 2
TEC
CEB Power 1
Anneal Power 1
CEB Power 2
Anneal Htrs
Side-1
CEB
Anneal Htrs
Side-2
Anneal Power
SBC
Operate Power 1
Mechanism
Power 1
MEB
Side-1
Mechanisms
Side-1
MEB
Side-2
Mechanisms
Side-2
Calibration
Power 1
Operate Power 2
Mechanism
Power 2
Calibration
Power 2
Calibration Lamp Controller
ACS Side-1 Checkout Programs
– Filter Wheel Check (#11094, 2 internal orbits, P.I. = C. Cox)
• Commands the SBC filter wheel to each of its positions (in both
directions)
• Verifies proper motion of wheel through encoder readout
• Test has been used previously (e.g., Side-2 switch)
– SBC MAMA Recovery (#11048, 4 internal orbits, P.I. = C. Cox)
• Initial MAMA turn-on and recovery from anomalous shutdown
– SBC was off when ACS was safed, so this is a conservative procedure
• Brings the MAMA back to operating condition while watching for
possible problems
– Signal processing check
– Intermediate high voltage ramp-up
– Full high voltage ramp-up
• Fold analysis provides detailed performance information
– Measures charge cloud size on anode and gain
• Darks and flats obtained during test
• Test has been used previously (e.g., Side-2 switch)
– Three Stage Contamination Check/Monitor
• Modification of Internal Flatfield Program (#11052, P.I. = R.
Bohlin)
– D2 flat for all 6 filters (6 orbits)
– Subset of filters (2 orbits) each week to monitor until external
(NGC6681) observation is obtained (maximum of three weeks)
• Modification of SBC Flux Calibration Program (#11056, P.I. =
J. Walsh)
– Single orbit ASAP on white dwarf standard WD1657+343
(visible now)
» F122M, F165LP, PR110L PR130L
– Second orbit one week later
• UV Contamination Monitor (#11050, P.I. = R. Gilliland)
–
–
–
–
–
Observation of NGC6681 (1 external orbit)
NGC6681 becomes visible ~ February 28
Comparison against historical data
Exposures in all 6 filters and 2 darks (in occultation period)
Repeat up to 4 times
Conversion of ACS programs
SPD and HST MO have asked INS to review existing cycle15 ACS
proposals to identify candidates for a conversion to WFPC2 or NICMOS
~ 120 programs are receiving a double technical review by INS.
An internal Feasibility Review panel will asses science and time with
guidance from the technical reviews.
Most of the PIs will be notified in early March. (PI can/will appeal
Review of phase-1s is coordinated by L.Smith.
Phase-2s will be processed following the usual procedures
(with limited reviews).
Backup Slides
WFPC2: Omega Cen - f814W (after anomaly event)
APB
Debris possible in
LVPS2 and APB
Side 2
Physical
Isolation
Hold Power
presently active
LVPS 2
LVPS 1
SBC
Fuse
Open
Fuse
OK
CEBs
Physical
Isolation
Only new powered
state in vicinity of
anomaly suspects is
MEB1 CS/SES
sections; Physical
Isolation is provided
MEB 1
MEB 2
STIS MEB
ACS, Side-2 with panels removed
APB is mounted to truss; here shown unsecured and resting in cavity
WFC Dark Current
WFC Hot Pixels
The new the temperature setpoint
brought dark Current and hot pixels
back to the level after only 18 months
on orbit.
TIPS-JIM Meeting
15 February 2007, 10am, Auditorium
1.
ACS Status Update
Marco Sirianni
2.
Update on NICMOS flat-field monitoring
Tomas Dahlen
3.
Speckle Interferometer for Measurement
Babak Saif
of Large Optical Structures
Next TIPS Meeting will be held on 15 March 2007.
Update on the NICMOS flat –field monitoring
Tomas Dahlen & NICMOS team
TIPS, Feb 15, 2007 - Tomas Dahlen
21
Update on the NICMOS flat –field monitoring
•
The current pipe-line flats are the “Post NCS On-Orbit
Flat-fields” from 2002
•
Flat-fields have been monitored every Post NCS cycle
most frequently in F110W, F160W and F222M
at least some flats have been taken in all available filters/grisms
Q: have the flat-fields changed over time since 2002 in a way that
would require an updated set to be constructed/distributed?
To investigate this we create
1) “Single-date-flats” from each observing run
2) “Epoch-flats” from combining flats over time-spans ~1 yr
TIPS, Feb 15, 2007 - Tomas Dahlen
22
Update on the NICMOS flat –field monitoring
Dates when flats have been taken (2002-2007)
Wave-length
Red=cam 1 Green=cam 2 Blue=cam 3
TIPS, Feb 15, 2007 - Tomas Dahlen
23
Update on the NICMOS flat –field monitoring
Changes in flat-fields:
1) Overall DQE changes
2) Spatial changes in normalized flats
TIPS, Feb 15, 2007 - Tomas Dahlen
24
Update on the NICMOS flat –field monitoring
Overall DQE changes
Figures show change in counts/s (with mean normalized to unity).
Total change 2002-2007 is typically a decrease by 1-2%
TIPS, Feb 15, 2007 - Tomas Dahlen
25
Update on the NICMOS flat –field monitoring
Could the decrease in DQE be due to change in detector temperature?
Pre and Post NCS DQE
Temperature variations
Post NCS
T=77K
Pre NCS
T=62K
Decrease in detector temperature would lower
DQE:
~2% per ΔK at F110
~1.5% per ΔK at F160
~1% per ΔK at F222
Gold points: Mounting cup temperature
Rest of points: Temp-from-bias (Bergeron 05)
(www.stsci.edu/hst/nicmos/documents/papers/2005_Calibration_Workshop)
TIPS, Feb 15, 2007 - Tomas Dahlen
26
Update on the NICMOS flat –field monitoring
Overall DQE changes
Gray lines: predictions from temperature dependence of DQE
CONCLUSION: Direction of DQE change is consistent with decrease in temp,
but seems smaller than suggested by the change of temp-from-bias.
If mounting cup temp reflects detector temp, then another explanation is needed
to explain the decrease in DQE
TIPS, Feb 15, 2007 - Tomas Dahlen
27
Update on the NICMOS flat –field monitoring
DQE spatial changes
As a measurement of spatial changes we define a “spatial ratio”:
R(sp)=mean(abs[ratio-image – 1]), where: ratio-image=date-flat/pipe-line flat.
Figures show change in R(sp) with time
Strongest variations at short wave-lengths
F110W: increase from 0.002 to 0.007
F160W: increase from 0.002 to 0.004
TIPS, Feb 15, 2007 - Tomas Dahlen
28
Update on the NICMOS flat –field monitoring
Ratio images for cam 1+F110W
200
2
200
3
200
5
200
6
200
4
200
7
R(sp) increases from 0.002 (2002) to 0.008 (2007) (Stretch = +/- 2%)
TIPS, Feb 15, 2007 - Tomas Dahlen
29
Update on the NICMOS flat –field monitoring
Ratio images for cam 2+F110W
200
2
200
3
200
4
200
5
R(sp) increases from 0.002 (2002) to 0.005 (2005)
TIPS, Feb 15, 2007 - Tomas Dahlen
30
Update on the NICMOS flat –field monitoring
Ratio images for cam 3+F110W
200
2
200
3
200
5
200
6
200
4
200
7
R(sp) increases from 0.002 (2002) to 0.006 (2007)
TIPS, Feb 15, 2007 - Tomas Dahlen
31
Update on the NICMOS flat –field monitoring
What is the photometric uncertainty due to the spatial
variations?
To investigate this, we measure the ratios between the new
flats and the pipe-line flats at random positions over the CCD.
Cam
1
Cam
2
Cam
3
Figure plots the distribution for F110W.
Cam1+F110W (2007)
34% probability of error >0.01 mag
1% probability of error >0.02 mag
Cam 2+F1110W (2005)
3% probability of error >0.01 mag
0% probability of error >0.02 mag
Cam3+F110W (2007)
14 % probability that error >0.01 mag
2 % probability that error >0.02 mag
TIPS, Feb 15, 2007 - Tomas Dahlen
32
Update on the NICMOS flat –field monitoring
Combining flats
1) Flats are divided into 5 epoch
Example: cam1 + F160W
IMAGE
S/N
t(bias) t(cup)
N(image) date
cam2_F160W_pipeline
596
cam2_F160W_ep1
836
76.49 77.11
24
~2002
cam2_F160W_ep2
864
76.33 77.12
24
~2003
cam2_F160W_ep3
706
76.13 77.19
16
~2004
cam2_F160W_ep4
449
75.61 77.17
8
~2005
cam2_F160W_ep5
700
74.99 77.15
14
~2006
8?
2) Each flat has a ‘use after’ date
3) And an associated temperature
4) Typical S/N = 500-1000
TIPS, Feb 15, 2007 - Tomas Dahlen
33
Update on the NICMOS flat –field monitoring
•
•
•
•
Conclusions (prel.)
DQE has decreased 1-2% since 2002
Spatial changes up to 1%
In total: ~0.03 mag photometric error (“worst case” F110W)
“Epoch” flats soon ready for delivery
TIPS, Feb 15, 2007 - Tomas Dahlen
34
TIPS-JIM Meeting
15 February 2007, 10am, Auditorium
1.
ACS Status Update
Marco Sirianni
2.
Update on NICMOS flat-field monitoring
Tomas Dahlen
3.
Speckle Interferometer for Measurement
Babak Saif
of Large Optical Structures
Next TIPS Meeting will be held on 15 March 2007.
Presentation not available yet; awaiting ITAR clearance
Speckle Interferometer
for Measurement of
Large Optical Structures
TIPS
February 15, 2007
Babak Saif, Bente Eegholm (SAI)
Perry Greenfield, Warren Hack
TIPS-JIM Meeting
15 February 2007, 10am, Auditorium
1.
ACS Status Update
Marco Sirianni
2.
Update on NICMOS flat-field monitoring
Tomas Dahlen
3.
Speckle Interferometer for Measurement
Babak Saif
of Large Optical Structures
Next TIPS Meeting will be held on 15 March 2007.