Instrument states
J.10.4.3.1.1
Requirement description
ACS entry into each of four instrument states (Boot, Hold,
Operate, Observe) shall be demonstrated. Operations shall
be commanded via stored commands transmitted over the
Supervisory Bus.
Relevant SMOV activities
Aliveness and functional test
Relevant SMOV proposals
N.A.
Requirement status
Satisfied
Discussion
Aliveness and functional test as well as subsequent
normal operations confirmed that the requirement is
satisfied.
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Guido De Marchi – SMOV 3B closeout review – 30.09.2002
Detector states
J.10.4.3.1.2
Requirement description
ACS entry into each of the defined detector states shall be
demonstrated. Operations shall be commanded via stored
commands transmitted over the Supervisory Bus.
Relevant SMOV activities
Aliveness and functional test
Relevant SMOV proposals
All
Requirement status
Satisfied
Discussion
Aliveness and functional test as well as subsequent
normal operations confirmed that the requirement is
satisfied.
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Guido De Marchi – SMOV 3B closeout review – 30.09.2002
Command and data interfaces
J.10.4.3.1.3
Requirement description
ACS command and engineering data interface via the RIU
and science data transmission via the Science Data
Formatter (SDF) shall be verified by monitoring of normal
configuration and science activities.
Relevant SMOV activities
All
Relevant SMOV proposals
All
Requirement status
Satisfied
Discussion
Normal operations have confirmed compliance with this
requirement.
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Guido De Marchi – SMOV 3B closeout review – 30.09.2002
Load and dump on-board memory
J.10.4.3.1.4
Requirement description
The ability to load and dump on-board memory shall be
demonstrated.
Relevant SMOV activities
ACS-02
Relevant SMOV proposals
9002
Requirement status
Satisfied
Discussion
The capability of the ACS to dump the CS memory has
been successfully verified via special commanding.
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Guido De Marchi – SMOV 3B closeout review – 30.09.2002
Science data buffer check
J.10.4.3.1.5
Requirement description
The ability to read and write data from and to the science
data buffer shall be demonstrated.
Relevant SMOV activities
ACS-03
Relevant SMOV proposals
9003
Requirement status
Satisfied
Discussion
The ACS science buffer RAM was checked for bit flips
during SAA passages through special commanding. A
total of 268 Mbit (i.e. four times a standard WFC image)
were dumped and only four bits were found to be affected.
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Guido De Marchi – SMOV 3B closeout review – 30.09.2002
Moving mechanisms
J.10.4.3.1.6
Requirement description
The performance of the cal/coronagraph Door, M3 Fold
Mechanism, Im1 and M1 Alignment and Focus Corrector
Mechanisms, WFC/HFC Filter Wheels 1 and 2, SBC Filter
Wheel, and WFC and HRC CCD shutters shall be verified.
Relevant SMOV activities
ACS-05, ACS-16
Relevant SMOV proposals
9005, 9016
Requirement status
Satisfied
Discussion
The correct functioning of all moving parts (calibration
door, filter wheels, M3 fold mechanisms, focus corrector
mechanism, shutters, etc.) has been verified through
specific proposals (see above) and in the course of
standard operations.
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Guido De Marchi – SMOV 3B closeout review – 30.09.2002
Calibration lamps and LED
J.10.4.3.1.7
Requirement description
The functionality of the ACS Tungsten calibration Lamps
and Pre-Flash LED shall be verified. Operation of the
deuterium lamp shall be deferred for an initial outgassing
period following release of the observatory, as defined in
the CARD.
Relevant SMOV activities
ACS-05, ACS-32
Relevant SMOV proposals
9005, 9032
Requirement status
Satisfied
Discussion
Calibration lamps were tested in orbit and illumination
levels were found to be consistent with those obtained in
ground vacuum tests. The capability of the CCD arrays to
be pre-flashed so as to mitigate CTE degradation has
been demonstrated. The Deuterium lamp has been tested
as expected.
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Guido De Marchi – SMOV 3B closeout review – 30.09.2002
Functionality of the detectors
J.10.4.3.1.8
Requirement description
Functionality of all three ACS detectors shall be
demonstrated through normal SMOV operations. This shall
include the proper accumulation of signal over a specified
time, data readout (including compressed data), and, for
the CCD, readout of a single subarray and selection of gain
settings.
Relevant SMOV activities
ACS-05, ACS-08
Relevant SMOV proposals
9005, 9008
Requirement status
Satisfied
Discussion
All three detectors were shown to operate nominally.
Readout through all amplifiers, with different gain settings
and of select subarrays of various size and location were
successful. The saturation levels meet the expectations.
Compression proved successful and is now routinely used
for dark and bias
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Guido De Marchi – SMOV 3B closeout review – 30.09.2002
CCD temperature set point
J.10.4.3.1.9
Requirement description
The ability of the TEC to cool and stably control the CCD
shall be tested at a small number of temperature set
points, in order to determine the coldest stable operating
point, which is the final setting desired. The requirement is
that this point be at least as cold as -80C.
Relevant SMOV activities
ACS-06
Relevant SMOV proposals
9006
Requirement status
Satisfied
Discussion
The operating temperatures were set at -80C for the HRC
and -77C for the WFC and were reached in 1.5 hr and 3
hr, respectively. They are stable to within 0.1 C. The -77C
operating temperature for the WFC was set so as to
decrease the load on the TEC in the absence of the
ASCS.
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Guido De Marchi – SMOV 3B closeout review – 30.09.2002
UV contamination monitoring
J.10.4.3.1.10
Requirement description
ACS operations shall minimize risk of contamination of
optics by materials outgassed internally or externally during
SM. ACS Cal Door shall be used to provide protection
while the OTA is viewing the bright earth during SMOV
program. A contamination monitoring program shall begin
as early as possible after the SM.
Relevant SMOV activities
ACS-10
Relevant SMOV proposals
9010
Requirement status
Satisfied
Discussion
ACS calibration door was shut during SM. No bright earth
observations were executed in SMOV phase. UV
monitoring programme started early on in SMOV to verify
contamination level. No evidence of contamination has
been seen so far.
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Guido De Marchi – SMOV 3B closeout review – 30.09.2002
SBC operations delay
J.10.4.3.1.11
Requirement description
High voltage operation of the ACS SBC MAMA detector
shall be delayed for an initial outgassing period following
release of the observatory, as defined in the CARD.
Relevant SMOV activities
ACS-10
Relevant SMOV proposals
9010
Requirement status
Satisfied
Discussion
The activation of the SBC high voltage was suitably
delayed to reduce any risks of contamination.
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Guido De Marchi – SMOV 3B closeout review – 30.09.2002
ACS to FGS alignment
J.10.4.3.2.1
Requirement description
The location of a reference ACS HRC camera aperture
shall be determined with respect to the FGS reference
frames to an accuracy of +/- 1 arcsec in V2-V3 coordinates
and 10 arcmin in aperture rotation angle.
Relevant SMOV activities
ACS-11
Relevant SMOV proposals
9011
Requirement status
Satisfied
Discussion
The accuracy on the location of the ACS apertures was
achieved and surpassed, with uncertainties of 0.05 arcsec
in the V2-V3 reference system and 3 arcmin in aperture
rotation angle.
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Guido De Marchi – SMOV 3B closeout review – 30.09.2002
Coronographic mask and finger
J.10.4.3.2.2
Requirement description
The relative positions of the ACS coronagraphic field
masks and Fastie finger, determined during ground test,
shall be confirmed.
Relevant SMOV activities
ACS-12
Relevant SMOV proposals
9012
Requirement status
Partialy satisfied
Discussion
Due to gravity release, the Fastie finger is no longer
exactly aligned with the coronographic mask. Observations
of very bright object might be affected by higher than
expected scattered light.
The Cycle 11 calibration program is evaluating the impact.
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Guido De Marchi – SMOV 3B closeout review – 30.09.2002
Coronographic acquisition
J.10.4.3.2.3
Requirement description
The ability of the FSW to perform isolated point source
acquisition onto the coronagraphic spots shall be
demonstrated with the ACS HRC detector. Successful
execution of these acquisitions will also demonstrate the
ability of the FSW to calculate the centroid of target
positions and to perform automated telescope pointing.
Relevant SMOV activities
ACS-12
Relevant SMOV proposals
9012
Requirement status
Satisfied
Discussion
Point source acquisition is performed as expected by the
FSW.
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Guido De Marchi – SMOV 3B closeout review – 30.09.2002
Corrector fine alignment
J.10.4.3.3.1
Requirement description
The encircled energy and image diameter shall be
measured over a grid of focus and tilt positions for both
IM1 and M1 correctors. These measurements will be used
to set the nominal corrector positions.
Relevant SMOV activities
ACS-13, ACS-14
Relevant SMOV proposals
9013, 9014
Requirement status
Satisfied
Discussion
By adjusting the IM1 and M1 corrector mechanisms the
image quality of the WFC and HRC was brought to the
required level.
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Guido De Marchi – SMOV 3B closeout review – 30.09.2002
Image quality
J.10.4.3.3.2
Requirement description
The image quality of the detectors over the full field shall
be measured via broad and narrow band imaging of stars.
The requirement for encircled energy in the WFC and HRC
is 75% within a diameter of 0.25 arcsec, through the
F502N filter. For the SBC is 30% within a diameter of 0.10
arcsec, through the Lyman alpha filter.
Relevant SMOV activities
ACS-15, ACS-23
Relevant SMOV proposals
9015, 9023
Requirement status
Satisfied (WFC, HRC), Partialy satisfied (SBC)
Discussion
The encircled energy is as follows:
WFC: 80% within 0.25 arcsec diam in F502N
HRC: 80% within 0.25 arcsec diam in F502N
SBC: 25% within 0.10 arcsec diam in F122M
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Guido De Marchi – SMOV 3B closeout review – 30.09.2002
Coronograph repeatibility
J.10.4.3.3.3
Requirement description
The internal stability of ACS from coronagraphic field stop
to HRC detector shall be monitored. The image shifts shall
be compared to the specified stability of 0.12 HRC pixels
RMS over 1300 s and +/- 0.20 HRC pixels over a three
hour period.
Relevant SMOV activities
ACS-16
Relevant SMOV proposals
9016
Requirement status
Satisfied, Partially satisfied
Discussion
The stability requirements have been met. Typical image
shift is < 0.09 HRC pixel rms in 2400 s, but drift rates of up
to 6 mas between acquisitions were seen.
Solution: execute target acquisition with coronograph in
place and do not shutter between alignments.
Commanding implementation in progress.
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Guido De Marchi – SMOV 3B closeout review – 30.09.2002
Pointing stability
J.10.4.3.3.4
Requirement description
The pointing and throughput stability of the OTA-ACS
combination shall be measured over several orbits to: 1.
Confirm that the typical Thermal environment after SM3B
does not cause unacceptable image drifts. 2. Determine
ACS image quality and pointing stability before and after
the start of NCS operation.
Relevant SMOV activities
ACS-17
Relevant SMOV proposals
9017
Requirement status
Satisfied
Discussion
Operational constraints imposed the test to be executed
after NCS activation, thus point 2. could not be verified by
design. The nominal jitter is 3 mas. Smooth drift rates of
up to 6 mas per hour have been detected, which are
similar to those seen in other SIs, probably due to the
FGS.
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Guido De Marchi – SMOV 3B closeout review – 30.09.2002
Point spread function
J.10.4.3.3.5
Requirement description
The ACS Point Spread Function (PSF) in normal imaging
and coronagraphic modes shall be measured.
Relevant SMOV activities
ACS-23, ACS-25
Relevant SMOV proposals
9023, 9025
Requirement status
Satisfied
Discussion
The PSF has been characterized for all cameras in most
imaging modes, including coronography. The measured
PSFs compare well, in general, with the pre-launch
expectations.
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Guido De Marchi – SMOV 3B closeout review – 30.09.2002
Geometric distortion
J.10.4.3.4.1
Requirement description
The plate scale, orientation and geometric distortion shall
be measured for each of the ACS channels by imaging an
astrometric field. Relative location of each aperture in the
FGS frame shall also be determined with these
measurements.
Relevant SMOV activities
ACS-27, ACS-28
Relevant SMOV proposals
9027, 9028
Requirement status
Satisfied
Discussion
Through the observation of dense stellar fields, the
platescale and geometric distortion have been assessed
for all three cameras (accuracy < 0.05 pixel rms). The
location of the apertures with respect to the FGS reference
frame is now accurate to within 0.05 arcsec.
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Guido De Marchi – SMOV 3B closeout review – 30.09.2002
Dark rate and annealing
J.10.4.3.4.2
Requirement description
Dark rate and read noise and CTE for each CCD detector
shall be measured, as well as dark rate for the SBC MAMA
detector. The hot pixel creation rate shall be assessed and
the efficacy of the hot annealing cycle shall be
demonstrated.
Relevant SMOV activities
ACS-05, ACS-22, ACS-31
Relevant SMOV proposals
9005, 8947, 9022, 9031
Requirement status
Satisfied
Discussion
Detector performances (dark rate, read noise and CTE)
have been constantly monitored throughout SMOV. Each
annealing cycle removes ~60% of hot pixel in WFC and
~80% of hot pixel in HRC. The installation of the ACSC is
expected to reduce the dark rate by one order of
magnitude.
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Guido De Marchi – SMOV 3B closeout review – 30.09.2002
Instrument sensitivity
J.10.4.3.4.3
Requirement description
Instrument sensitivity vs. wavelength shall be measured for
a subset of ACS modes. Sensitivity measurements shall be
performed using astronomical standard stars. As part of
this process, UV sensitivity measurements shall be
obtained as early as possible, to enable early trending of
UV sensitivity.
Relevant SMOV activities
ACS-20, ACS-10
Relevant SMOV proposals
9020, 9010
Requirement status
Satisfied
Discussion
The sensitivity of all three cameras with all filters in most
instrument modes has been tested on standard stars. A
UV monitoring programme has been started to identify any
sensitivity decrease at UV wavelengths (none seen so far).
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Guido De Marchi – SMOV 3B closeout review – 30.09.2002
Polarization calibration
J.10.4.3.4.4
Requirement description
The instrumental polarization as function of wavelength
shall be measured for both WFC and HRC channels.
Relevant SMOV activities
N.A.
Relevant SMOV proposals
N.A.
Requirement status
N.A.
Discussion
It was decided, before launch, to defer this activity to the
Cycle 11 calibration period.
It should be noted that a TOO Proposal required us to
implement this proposal on a fast track as a Cycle 11
Interim calibration program.
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Guido De Marchi – SMOV 3B closeout review – 30.09.2002
Flat field stability
J.10.4.3.4.5
Requirement description
The flat field uniformity per pixel and cosmetic defects shall
be measured for each detector. The ability to determine the
residual variations using the ACS internal calibration
sources shall be demonstrated. The difference between
sky flats and internal flats and temporal stability of the flat
field correction shall be assessed.
Relevant SMOV activities
ACS-18, ACS-19, ACS-24
Relevant SMOV proposals
9018, 9019, 9024
Requirement status
Satisfied
Discussion
Flat field uniformity has been verified for all three
detectors, differences from the ground calibration have
been characterized and internal flats are now used to
monitor variations. The first generation flat field are good
to ~1%. Second generation sky flats will be generated on
~6 month timescale when enough deep imaging proposals
have accumulated to achieve required S/N.
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Guido De Marchi – SMOV 3B closeout review – 30.09.2002
Early release observations
J.10.4.6.1
Requirement description
SMOV activities shall include early release observations
with at least ACS and NICMOS science instruments. The
resulting science data products shall be released into the
public domain to demonstrate the improved HST
capabilities.
Relevant SMOV activities
ERO-01
Relevant SMOV proposals
8992
Requirement status
Satisfied
Discussion
Astounding astronomical images have been collected and
released, which have had impressive resonance both in
the media and in the astronomical community worldwide.
These data have shown that the ACS can improve by an
order of magnitude the discovery efficiency of the HST.
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Guido De Marchi – SMOV 3B closeout review – 30.09.2002
ACS Status
˜
The ACS group has performed above and beyond
expectations during SM3B/SMOV
– ACS finished SMOV ahead of schedule
• Moved program up ~3 weeks: enabled by effective
planning
– Key science enabled
• WFC flats & zero-points installed during SMOV
• Bias and daily dark program operational since April
• Geometric calibration characterized during SMOV
• Initial image quality assessment completed
• Image stability verified
– Science operations started in record time
– High impact ERO program
– OPUS/CALACS performed with no major errors
• Majority of fixes to support calibration
ACS Group key players
Mark Clampin
ACS Group Lead
Guido DeMarchi
Instrument Scientist (SISD)
Ron Gilliland
Instrument Scientist (SISD)
Chris O’Dea
Instrument Scientist (SISD)
William Sparks
Instrument Scientist (SISD) [Deputy]
Roland van der Marel
Instrument Scientist (SISD)
George Hartig
Instrument Scientist (NISD)
Ralph Bohlin
Instrument Scientist (NISD)
Max Mutchler
Data Analyst (SISD)
Jennifer Mack
Data Analyst (SISD)
Doug van Orsow
Data Analyst (SISD)
Cheryl Pavlovsky
Data Analyst (SISD)
Colin Cox
Senior Software Analyst (SISD)
John Krist
Senior Optical Analyst (SISD)
Warren hack
Programmer (SSG)
Alan Welty
Commanding (ESS)
Tom Wheeler
Engineering (ESS)
Alison Vick
Program Coordinator
Beth Pierello
Program Coordinator
ST-ECF (Walsh, Pasquali, Pirzkal)
Grism Support
ACS IDT key players
SBC Image Quality
Flux Arc s e c -2 (relative to total stellar flux)
Coronagraph Performance
10
-2
1.8" Spot Azimuthal Me d ian Profiles
F435W
F814W
10 -4
Direct (no coronagraph)
10 -6
C o ronagraph only
10 -8
Co ronagraph - star
10
-10
0
2
4
Arcsec
6
8
Flat fields
Photometric response for a given star is now the same to ~1% for
any position in the WFC field of view.
˜
˜
Quality of flat fielding is shown in 47 Tuc CMD
Annealing
WFC
60000
40000
20000
0
0
30
60
90
Days since March 30th
120
150
2500
2000
Hot Pixels with e/s > 0.08
Hot Pixels with e/s > 0.04
80000
1500
HRC
1000
500
0
0
30
60
90
Days since March 30th
120
150