Goddard Space Flight Center
HST Project
ACS-R
SMOV Optimization Campaign
Iteration 1 Summary
June 2, 2009
Ed Cheng
Goddard Space Flight Center
Summary
HST Project
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Performance is outstanding, and as intended.
ACS-R Team and STScI agree that the Optimization Campaign can be
truncated.
 Current SMS constraints allow us to shorten to two weeks.
 Enables early start to normal SMOV activities (and science).
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Discovered a minor bug and making some minor tweeks.
Realtime uplink commanding is limited to adjusting one set of voltage
offsets.
 Mostly affects half-speed mode.
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Bias
100 sec Dark
Mission accomplished!
ACS-R SMOV Optimization Campaign
2
June 2, 2009
Goddard Space Flight Center
Performance Summary
HST Project
Parameter
Jan 2007
(actual)
May 2009
(predicted)
“Problemmatic”
May 2009
(OC Iter 1)
Read noise (e-)
C&S: 5.5
DSI: 4.0
10
DSI: 4.0-4.8
C&S: 4.4-5.7
Dark current
(e-/pix/hr)
10.7
15
100
20-25
Hot pixels (%)
0.68
1.1
1.5
1.1
84,000
84,000
40,000
~80,000
< 0.1
< 0.1
0.5
TBD
0.999949
0.999921
0.99990
0.99989
Cross-talk
4x10-5
4x10-5
4x10-4
1x10-4
Gain instability (%)
< 0.1
< 0.1
< 0.2
TBD
Full well depth (e-)
Non-linearity (%)
CTE
ACS-R SMOV Optimization Campaign
3
June 2, 2009
Goddard Space Flight Center
Optimization Campaign Timeline
HST Project
Deletion Recommended
Now
ACS-R SMOV Optimization Campaign
4
June 2, 2009
Goddard Space Flight Center
Iteration 1 Main Discoveries
HST Project
Discovery
Action
Minor timing irregularities noted in
oscilloscope mode data.
Bug in Flight Assembly Code found and
resolved in ground testing. No impact to
normal operations. Will be repaired in
final FAC drop.
Half-speed mode noise is unrealistically
low.
Saturation of ADCs because offset is not
optimized for half-speed mode. Offset
change requested in realtime uplink.
Science Data Control Register
Examining result more carefully. Taking
optimization shows lower noise for a non- a little more time before deciding on
default value.
uplinking any new values.
Reset Gate voltage is well-behaved at a
lower value than pre-failure.
Keeping the new default (8V) instead of
the pre-failure value (12V). Slight noise
benefit and stability benefit. Margin
demonstrated by proper operation at 7V.
“Hypersensitivity” of Quadrant to C a
small change in Vod.
Investigation in progress. Default value
appears to give good performance.
ACS-R SMOV Optimization Campaign
5
June 2, 2009
Goddard Space Flight Center
Realtime Uplink Request
HST Project
ACS-R SMOV Optimization Campaign
6
June 2, 2009
Goddard Space Flight Center
To Do
HST Project
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Understand the funnies and figure out if we want an uplink for Iteration 2
to address these.
Confirm results with Iteration 2 data.
ACS-R SMOV Optimization Campaign
7
June 2, 2009