Telescope and Instrument Performance
Summary (TIPS)
21 February 2002
AGENDA
1.
2.
3.
4.
5.
SISD Perspective
Cycle 11 Update and Cycle 12 Plans
WFPC2 Status
ACS Flat Fields
WFC3 Status (Detectors)
Harry Ferguson
David Soderblom
Anton Koekemoer
Ralph Bohlin
Massimo Robberto
Next TIPS Meeting: 21 March 2002
SISD Perspective
• Launch Feb 28
• New information
– Data handbooks released yesterday
• Major update, now modular (separate “books” for different
instruments), and available both in PDF and HTML
• Kudos to the team, including Bahram Mobasher, Jennifer
Mack, Tom Brown, Sylvia Baggett, Matt McMaster, Mark
Dickinson, Ed Nelan, Russ Makidon, Susan Rose, and Jim
Younger
– New NICMOS web site online
– work about to start on FGS/OSG and HD internal site
21 Feb 2002
H. Ferguson TIPS
1
Near-term priorities
• SMOV
– Science enabled:
•
•
•
•
•
FGS astrometry
STIS 3/27 (CCD & MAMA)
WFPC2 3/27
ACS basic ccd science 4/6 – SBC 5/6
NICMOS 4/24
• Cycle-11 Calibration plan
– Work beginning now
– Director’s office review early May
– Phase-2 proposals mid May
• Calibration workshop
– October, 2002 coordinated with ADASS
• Either as part of ADASS (downtown), or tacked on to the end (held at
STScI).
• Need volunteers for organizing committee
21 Feb 2002
H. Ferguson TIPS
2
• Dither working group formed
– Anton Koekemoer coordinating
– Coordinate near-term testing
– Develop road map for dither package evolution
• SHARE/FASST committees
• Study of Hubble Archive & Reprocessing Enhancements
• Future of Archive Services at Space Telescope
– Implementation study to begin, led by Chris Blades
21 Feb 2002
H. Ferguson TIPS
3
• Cycle-12 Preparations
• Unofficially: call for proposals likely to be released
October 2002
• proposals due Jan 24, 2003
• Execution starts July 2003
• Compressed schedule will reduced time from proposal to
receipt of data, but also poses a challenge when rolling out APT
– APT
• Rollout of NICMOS & STIS exposure-time calculators in June
– Common background model for all instruments
• Phase-1 tools to be released in June
– Incorporation of help facility requires coordination with HD on
documentation
• Orbit planner prototype testing underway
21 Feb 2002
H. Ferguson TIPS
4
Hubble Operations Dept.
Cycle 11 Phase II:
GO
Programs
Submitted
Not submitted; granted
extensions
Not submitted;
delinquent
GO Orbits
Percent
SNAP
orbits Programs
SNAP
Targets
148
2835
86%
11
1456
10
419
13%
2
202
6
38
1.1%
0
0
TIPS: 2002-02-21
1 of 4
Cycle 12 Proto-Schedule:
CP input due:
CP issued:
Phase I proposals due:
TAC meets:
Notification to proposers:
Phase II programs due:
Start of Cycle 12:
July 10, 2002
October 15, 2002
January 24, 2003
March 24-29, 2003
April 4, 2003
May 16, 2003
August 1, 2003
TIPS: 2002-02-21
2 of 4
Servicing Mission 3B: Summary
Nominal science SMS constructed for week of launch
(02056). It includes transition visits (configure SIs to
nominal SMS boundary states, slew to rendezvous
attitude, and provide command load breaks for
intercept).
•
Transition visits once per day, ~6 hours after launch
time.
•
Must be at rendezvous attitude no later than 7 hours
after launch.
•
Science continues if launch delayed.
Intercept SMS also created to maintain rendezvous
attitude (i.e., all science removed after rendezvous
time). Intercept SMS applies to one launch day only.
TIPS: 2002-02-21
3 of 4
Transition
If launch occurs, intercept to science SMS needed.
Science SMS interrupted and intercept SMS starts to
stay at the rendezvous attitude for an extended time.
The intercept time occurs within the transition visit so
that the FOT has 5 to 7 hours after launch to uplink the
new command loads. This timing requires delivery of
intercept SMS before launch.
Launch Delays
If launch delayed, intercept does not occur and
science SMS continues. New intercept SMS generated
for next launch opportunity. There are four intercept
opportunities in the 02056 calendar: Thursday through
Sunday.
If launch is delayed into the following week (02063),
we handle it as above. The 02063 SMS is built anyway
so that it is available on time.
TIPS: 2002-02-21
4 of 4
SPACE TELESCOPE SCIENCE INSTITUTE
TIPS: 21 February 2002
WFPC2
Anton Koekemoer
Wide Field and Planetary Camera 2
• WFPC2 News:
– New WFPC2 Group Lead: Brad Whitmore (as of January 1, 2002)
• New WFPC2 Documentation
• Cycle 11 WFPC2 Science Usage
• WFPC2 SM3B Plans
• WFPC2 Software Development
• Filter Wheel Rotation Anomaly
1
SPACE TELESCOPE SCIENCE INSTITUTE
TIPS: 21 February 2002
WFPC2
Anton Koekemoer
Recent WFPC2 Documentation
ISRs:
WFPC2-2001-09 The WFPC2 Photometric CTE Monitor
Heyer
WFPC2-2001-10 An Improved Geometric Solution for WFPC2
Casertano, Wiggs
WFPC2-2001-11 Summary of WFPC2 SM3B Plans
Koekemoer et al.
WFPC2-2002-01 WFPC2 Clocks-ON Close Out
Schultz et al.
WFPC2-2002-02 WFPC2 Flatfield Updates 1995 - 2001
Koekemoer et al.
HST Dither Handbook v2.0, Jan. 2002 (Koekemoer et al.)
WFPC2 Data Handbook v4.0, Feb. 2002 (Baggett & McMaster, Editors;
Mobasher, Chief Editor, HST Data Handbook)
2
TIPS: 21 February 2002
WFPC2
Anton Koekemoer
SPACE TELESCOPE SCIENCE INSTITUTE
Cycle 11 WFPC2 Science Usage
Proposal ID
PI
Orbits
Filters
9354
Karkoschka
1
(Prime)
F225W,F336W,F410M,F467M,F588N,F673N,F953N,FQCH4N
9356
Zijlstra
60
(Prime/Snap)
F502N,F547M,F656N
9367
Hazard
22
(Prime)
F225W
9371
Chu
2
(Prime)
F555W,F675W,F814W
9385
Lemmon
2
(Prime)
F336W,F439W,F547M,F588N,F673N,FQCH4N
9393
Sromovsky
14
(Prime)
F225W,F336W,F410M,F467M,F547M,F588N,F631N,F673N,
F791W,F850LP,F935N,FQCH4N
9420
Davidson
6
(Prime)
F336W,F375N,F502N,F631N,F656N,F658N,F673N,F953N
9436
Kuijken
3
(Prime)
F814W
9461
Biretta
1
(Prime)
F300W,F450W,F606W,F814W
9481
Gardner
200
(Parallel)
F300W
9318
Casertano
(Pure Parallel)
F300W,F410M,F450W,F467M,F606W,F814W
9319
Casertano
(Pure Parallel)
F300W,F606W
Note: Other Cycle 11 GO Programs are also now using WFPC2 in parallel.
3
SPACE TELESCOPE SCIENCE INSTITUTE
TIPS: 21 February 2002
WFPC2
Anton Koekemoer
WFPC2 SM3B Preparations
State of WFPC2 after HST release
• WFPC2 will be placed in PROTECT/DECON (+22 C)
• Cooldown to -88 C as soon as practical after end of 12-day BEA
WFPC2 Pre-SM3B Calibration Program
• 8943: WFPC2 Lyman-Alpha Check: Pre-SM3B Baseline (Nov. 2001)
WFPC2 SMOV Calibration Programs
• 8950: WFPC2 SM3B Cooldown, Contamination Monitors,
Photometric Monitors, Internal Calibrations, Focus Checks
• 8951: WFPC2 SM3B Lyman-Alpha Check
• 8952: WFPC2 SM3B Flat Field Calibration
• 8953: WFPC2 SM3B Relative Photometry Check
• 8954: WFPC2 SM3B Point Spread Function Verification
4
SPACE TELESCOPE SCIENCE INSTITUTE
TIPS: 21 February 2002
WFPC2
Anton Koekemoer
WFPC2 Software Development
Revised WFPC2 Exposure Time Calculator (Biretta et al.)
• Additional options for photometry (either “optimal PSF weighting or simple
aperture photometry in a user-specified radius)
• More flexible background specification:
– high/average/low, or explicit user-specified value
– sky backgrounds calculated based on target position and sun angle
Dither Working Group (Koekemoer et al.)
• Cross-instrument group to coordinate testing new release of drizzle2.6 for
WFPC2, STIS, NICMOS (and also PyDrizzle, in conjunction with ACS team)
• Forum for discussing specifications for future dither software
New Darks software (Platais, Riess, Koekemoer)
• Software to facilitate creation of darks by users
5
SPACE TELESCOPE SCIENCE INSTITUTE
TIPS: 21 February 2002
WFPC2
Anton Koekemoer
WFPC2 Filter Wheel Rotation Anomaly
(Gonzaga et al., ISR in preparation)
Was discovered during routine checks of gain ratios over time:
• Measurement of average countrate in central 400x400 pixels ofVISFLAT
images (in FR533N), for gain 7 relative to gain 15
• Nominal ratio should remain constant ~ 1.97
• “Quantized” jumps were found above and below this value, to 1.90 and 2.05
6
SPACE TELESCOPE SCIENCE INSTITUTE
TIPS: 21 February 2002
WFPC2
Anton Koekemoer
Visual inspection revealed spatial shifts in filter features on the images:
Example: two WF3 images in the FR533N filter, showing a shift of ~10 pixels
7
SPACE TELESCOPE SCIENCE INSTITUTE
TIPS: 21 February 2002
WFPC2
Anton Koekemoer
More quantitative measurement of shift: plot cross-sections
Example: Vertical cross-section taken through two FQCH4N VISFLAT images
(i.e. varying y-pixel location, for a constant x-pixel location):
Average of Columns 1110 to 1130 in Mosaic’d images u2qq1707t & u2qq0z07p
1500
1250
Measured Region
at approx. (1120,700)
Counts
1000
750
500
250
0
250
500
750
Rows
1000
1250
1500
8
SPACE TELESCOPE SCIENCE INSTITUTE
Could the shift be caused by filter wheel displacements?
Filter Wheel Layout:
2.277 inches
(2077.8 pix)
WFPC2 Geometry:
Filter Wheel
Rotation Axis
TIPS: 21 February 2002
WFPC2
Anton Koekemoer
9
SPACE TELESCOPE SCIENCE INSTITUTE
TIPS: 21 February 2002
WFPC2
Anton Koekemoer
Use the measured x,y shifts to calculate a rotation offset angle:
Typical values for the rotational displacement are ~0.4 - 0.5 deg.
Final filter movement is sensed by means of IR LED encoder -> possibilities:
• damping pulse for final filter placement is becoming erratic
• Radiation degradation may be affecting the LED/sensor mechanism
10
ACS Flat Fields
Ralph Bohlin
REFERENCES FOR ACS FLAT FIELDS:
FLATS: PRELIMINARY HRC DATA AND ON-ORBIT PLANS, Bohlin, R., Hartig,
G., Lindler, D., Meurer, G., & Cox, C. 1999, Instrument Science Report, ACS 99-01,
(Baltimore:STScI).
FLATS: SBC DATA FROM THERMAL VACUUM TESTING, Bohlin, R., Hartig, G.,
& Meurer, G. 1999, Instrument Science Report, ACS 99-02, (Baltimore:STScI).
ACS FLAT-FIELD GROUND CALIBRATION PLANNING, Sparks, Wm., Hartig, G.,
Bohlin, R., & Martel, A. 2000, Instrument Science Report, ACS 00-04,
(Baltimore:STScI)
FLATS: PRELIMINARY WFC DATA AND PLANS FOR FLIGHT FLATS, Bohlin, R.
C., Hartig, G., & Tsvetanov 2000, Instrument Science Report, ACS 00-10,
(Baltimore:STScI)
HRC AND WFC FLAT FIELDS: STANDARD FILTERS, POLARIZERS, AND
CORONOGRAPH, Bohlin, R. C., Hartig, G. & Martel, A. 2001, Instrument Science
Report, ACS 01-11, (Baltimore:STScI)
HRC AND WFC FLAT FIELDS: RAMP FILTERS, Bohlin, R, C. & Hartig, G. 2002,
Instrument Science Report, ACS 02-01, (Baltimore:STScI)
HRC AND WFC FLAT FIELDS: DISPERSORS, ANOMALIES, AND
PHOTOMETRIC STABILITY, Bohlin, R, C. & Hartig, G. 2002, Instrument Science
Report, ACS 02-xx, (Baltimore:STScI)
RELATIVE GAIN VALUES AMONG THE FOUR WFC AMPLIFIERS, Bohlin, R, C.,
Hartig, G., & Sparks, Wm. 2002, Instrument Science Report, ACS 02-03,
(Baltimore:STScI)
HOW MANY ACS CCD MODES?
Single Filters
(2 G800L from ECF)
2 Filter: Polarization
(omit ramps and spectra)
HRC Coronograph
(also omit 16 of 24 Pol modes)
Totals
2x more for complete –1, +1 step flat:
SBC: 8 Filters on Wheel 3 only 2 Flats
required
Current Grand Total
HRC
WFC
Possible
Delivered
24
19
43
41
72
57
129
87
24+72=96
…
96
40
192
76
268
168
+536
+26
2
196
TIPS meeting – Feb 21, 2002
WFC3 Status (detectors)
M. Robberto
UVIS CCD
IR FPA / Mux
"Data contained herein is exempt from ITAR regulations under CFR 125.4(13) -- data approved for public disclosure."
February 21, 2002
TIPS meeting
1
CCD Status
• Marconi has completed all deliveries.
– Original order of 6 devices.
• One (# 23) damaged back in Nov 01 and returned to Marconi for analysis
• Four (# 18 & # 178 and # 37 & # 40) selected for flight and characterized.
• One held in reserve.
– Supplemental order of 2 devices.
• Both (# 48 and #50) received, characterization of #38 underway in the
DCL.
– Closeout meeting held on 15 January 2002.
– Last detectors #37, #40, #50 shipped at Ball next week
• These are exceptional devices, with extremely uniform
behavior from device to device.
"Data contained herein is exempt from ITAR regulations under CFR 125.4(13) -- data approved for public disclosure."
February 21, 2002
TIPS meeting
2
WFC3 CCD Innovations
•
Low readout noise.
– Improves narrow-band and UV imaging sensitivity and enables shorter
sub-exposures in a long integration (providing more redundant images or
more thorough drizzling).
– Will challenge the instrument electronics.
•
High near-UV QE.
– Major WFC3 scientific thrust is enabled.
•
Extremely uniform detector spatial response.
– Simplifies calibration and improves photometric accuracy.
•
Charge injection for CTE degradation mitigation.
– Slows down effective device aging.
•
Fringing characterization and prediction for long wavelength
observations.
– Improves accuracy of narrow-band and narrow-line observations.
"Data contained herein is exempt from ITAR regulations under CFR 125.4(13) -- data approved for public disclosure."
February 21, 2002
TIPS meeting
3
Marconi CCDs Have
Very Low & Consistent Readout Noise
Read Noise For Marconi CCD43 Engineering Grade Devices
#187
#165
#188
#152
#189
#166
Units Spec Marc. DCL Marc. DCL Marc. DCL Marc. DCL Marc. DCL Marc. DCL
3
1.6
2.9
2.6
3
1.7
3.2
2.4
3.5
3.3
RN (A) e
(B) e
3
1.7
1.8
2.6
2.9
1.6
3
1.6
3.5
3.6
Read Noise For Marconi Flight Candidate Devices
#136
#178
#018
#023
#037
#040
#050
Units Spec Marc. DCL Marc. DCL Marc. DCL Marc. DCL Marc. DCL Marc. DCL Marc. DCL
3
3
3
2.2
3.1 <2.7 2.9
2.8
3.4
2.1
3.1
RN (A) e
(B) e
3
3.5
3
2.3
3.1 <2.7
3
3.5
3.1
2.2
3.1
Flight pair number 1
--- Flight pair number 2 candidates ---
By comparison, the SITe devices in the ACS instrument have
read noises in the range 4.5-5.5 e"Data contained herein is exempt from ITAR regulations under CFR 125.4(13) -- data approved for public disclosure."
February 21, 2002
TIPS meeting
4
Marconi CCDs Exceed Expectations for
High UV QE
Pair Number 1 flight CCDs versus the Specification
"Data contained herein is exempt from ITAR regulations under CFR 125.4(13) -- data approved for public disclosure."
February 21, 2002
TIPS meeting
5
IR-FPA Status
Detector
#
11
14
15
18
20
21
22
24
25
27
30
31
32
33
Produced
13-Mar-01
30-Mar-01
18-Apr-01
20-Apr-01
20-May-01
25-May-01
13-Jun-01
14-Jun-01
6-Jul-01
19-Jul-01
1-Aug-01
23-Aug-01
4-Oct-01
13-Sep-01
MILESTONES
Comments
Due
Delivered Test report
9-Apr-01 27-Apr-01 26-Mar-01 pixel crosstalk
23-Apr-01 27-Apr-01 10-May-01 pixel crosstalk
23-Apr-01 16-May-01 30-May-01 QE non-uniformity at cutoff
4-Jun-01
8-Jun-01
11-Jul-01 at Ball, integrated into qual unit
4-Jun-01
8-Jun-01
18-Jul-01
4-Jun-01
8-Jun-01
20-Jul-01
6-Jul-01
18-Jul-01
1-Sep-01
6-Jul-01
18-Jul-01
1-Sep-01
6-Jul-01
18-Jul-01
1-Sep-01 warm image shows unbonded pixels
3-Aug-01
7-Sep-01 15-Oct-01 Flight backup candidate
3-Aug-01
7-Sep-01
8-Nov-01 Flight backup candidate
3-Aug-01 12-Oct-01
1-Oct-01 Flight candidate
4-Oct-01 26-Oct-01
8-Nov-01
4-Oct-01 12-Oct-01
9-Nov-01 Flight candidate
• In addition, MUX #10 was delivered to Ball and is being integrated into
the surrogate IR detector build
"Data contained herein is exempt from ITAR regulations under CFR 125.4(13) -- data approved for public disclosure."
February 21, 2002
TIPS meeting
6
Rockwell Test Results
FPA #
Parameter
Gain
Read noise
Dark Current
Persistence
QE @ J
QE @ 1.5 ? m
Units
e - /mV
e /pix
11
14
361
65
15
18
20
21
22
24
300
40
321
47.2
315
47
274
39
315
43
315
47.5
0.049
0.34
0.37
0.104
0.388
0.357
1.42
45.2
0.504
47.1
e - /pix/sec
e /pix/sec
after 96 min
%
72.7
27.9
24
20.6
42.7
0.165
32
%
86.1
31.2
27.1
33.8
64.6
44.4
58.8
50
%
ke -
>99
>97
>99
>99
>97
>90
>97
>85
>99.7
>102
>99.1
>100
Operability
Full Well
0.5
0.6
Parameter
Gain
Read noise
Units
e /mV
e - /pix
25
308
27
499
68.8
30
350
57.7
FPA #
31
347
44.7
Dark Current
e - /pix/sec
e- /pix/sec
after 96 min
0.153
0.136
0.133
0.037
0.086
0.129
0.041
0.499
0.207
0.43
0.067
0.083
0.125
0.055
%
%
50.6
68.2
39
53.6
43.8
55.9
61.3
81.1
25.4
39.3
55.1
76
28.4
38.9
Persistence
QE @ J
QE @ 1.5 ? m
32
300
33.9
33
332
48.1
34
360
42.1
Operability
%
>99.2
>99.7
>99.8
>99.7
>99.7
>99.7
>99.6
Full
keexempt from >104
>150
>110
>110
>100
>132
"Data Well
contained herein is
ITAR regulations
under CFR
125.4(13) -->100
data approved
for public disclosure."
February 21, 2002
TIPS meeting
7
RSC Dark Current and QE
Results
min
The dark current
and QE
performance of
the detectors
showed dramatic
improvement
over the course
of the program
100%
100%
min
"Data contained herein is exempt from ITAR regulations under CFR 125.4(13) -- data approved for public disclosure."
February 21, 2002
TIPS meeting
8
Dark current
1
y = 3E-17e0.2313x
0.01
10
0.001
140
145
150
155
160
165
Temperature (K)
FPA15:
DC= 0.04e/s @ 150K
1
10
0.1
0.01
135
140
145
150
155
160
temperature (K)
FPA18:
DC= 0.34e/s @ 150K
165
dark current (e/s)
0.0001
135
dark current (e/s)
dark current (e/s)
0.1
1
0.1
0.01
144
146
148
150
152
154
temperature (K)
FPA22:
DC= 0.39e/s @ 150K
"Data contained herein is exempt from ITAR regulations under CFR 125.4(13) -- data approved for public disclosure."
February 21, 2002
TIPS meeting
9
156
FPA31 dark current ramps
FPA31010800s
7200s Exposure
FPA31
exposure
Dark Current vs Read Number
d07_150k_dk_00XX.fits
59000
01
02
03
58000
04
05
06
57000
Mean Sci Pix (DN)
07
08
09
56000
10
11
12
55000
13
14
15
54000
16
18
20
53000
22
1
3
5
7
9
Read Number
11
13
15
17
24
C. Hanley 11 Jan 2002
• Ramp slope decreases with time
• Second read decreases with time
"Data contained herein is exempt from ITAR regulations under CFR 125.4(13) -- data approved for public disclosure."
February 21, 2002
TIPS meeting
10
FPA31 dark current settling time
Cycle power
FPA31
Mean Signal in Last Read vs Time
59000
A sequence of 20 ramps 3 hr
long, each with 1+16 samples
(one every 675s)
58000
Mean Sci Pix (DN)
57000
56000
55000
54000
53000
0
50000
1day
100000
150000
Time (seconds)
2days
200000
250000
"Data contained herein is exempt from ITAR regulations under CFR 125.4(13) -- data approved for public disclosure."
February 21, 2002
TIPS meeting
11
FPA31 dark current settling time
Cycle power
FPA31 Dark Current Over Time
0.2
{
CEIS
0.1
0
Dark Current (e-/s)
-0.1
-0.2
-0.3
-0.4
FPA31 dark current settles
after ~ 2 days
-0.5
-0.6
-0.7
-0.8
0
50000
1day
100000
150000
Time (seconds)
2days
200000
250000
"Data contained herein is exempt from ITAR regulations under CFR 125.4(13) -- data approved for public disclosure."
February 21, 2002
TIPS meeting
12
FPA31 dark anomaly
FPA31 appears to have
two populations of pixels,
each with their own dark
current behavior.
November 01 data
"Data contained herein is exempt from ITAR regulations under CFR 125.4(13) -- data approved for public disclosure."
February 21, 2002
TIPS meeting
13
FPA31 dark – 2 populations
1hr
1hr
1hr
October 24 data
"Data contained herein is exempt from ITAR regulations under CFR 125.4(13) -- data approved for public disclosure."
February 21, 2002
TIPS meeting
14
Dark current summary
• FPA31 dark current is ~0.05e/s/pix, once the FPA is set.
• Settling time is ~36 hr.
• For the first ~36 hr the dark current is dominated by a large
drift in the output signal.
• Irregular behavior still present after 36 hr on short ramps.
• The drift is similar to the “reset anomaly”, but it has larger
time-scale and is related to the FPA power cycling. Reset
anomaly can be corrected.
• Power cycling of IR FPA is not expected to routinely occur
on WFC3.
"Data contained herein is exempt from ITAR regulations under CFR 125.4(13) -- data approved for public disclosure."
February 21, 2002
TIPS meeting
15
Quantum efficiency
FPA31
1.0
0.9
0.8
Q1
0.7
Q2
0.6
Q4
Q3
0.5
OK
0.4
$
0.3
$$
0.2
0.1
0.0
500
700
900
1100
1300
1500
1700
1900
January 11 data
"Data contained herein is exempt from ITAR regulations under CFR 125.4(13) -- data approved for public disclosure."
February 21, 2002
TIPS meeting
16
Readout noise
active area
electrons
electrons
inboard
36
12
34
10
32
8
30
SB Jan 16,2001
"Data contained herein is exempt from ITAR regulations under CFR 125.4(13) -- data approved for public disclosure."
February 21, 2002
TIPS meeting
17
Readout noise
Summary of the RON measured on active pixels
•
•
•
•
•
FPA#15:
FPA#18:
FPA#22:
FPA#25:
FPA#31:
32 e/pix/read
30 e/pix/read
30 e/pix/read
28 e/pix/read
31 e/pix/read
"Data contained herein is exempt from ITAR regulations under CFR 125.4(13) -- data approved for public disclosure."
February 21, 2002
TIPS meeting
18
Reference pixels
4×507 horizontal
1×507 horizontal
1014 × 1014
active pixels
1×507 vertical
4×507 vertical
1014 × 5 reference pixels
"Data contained herein is exempt from ITAR regulations under CFR 125.4(13) -- data approved for public disclosure."
February 21, 2002
TIPS meeting
19
Fixing reference pixels
Vertical reference pixels are “light sensitive”
Adding a delay time at the beginning of each line read eliminates the effect
50
1ms
0ms
45
2ms
3ms
8ms
40
35
adu
30
Horizontal
25
Vertical
20
15
10
5
0
0
6
12
18
24
30
Fowler DCS
"Data contained herein is exempt from ITAR regulations under CFR 125.4(13) -- data approved for public disclosure."
February 21, 2002
TIPS meeting
20
Reference pixels drift in 60hr
59000
dark
57000
vertical
horizontal
Reference pixels are stable within ~100e
over a time-scale of ~2.5 days
53000
51000
49000
47000
45000
0
50
100
150
200
250
300
sample
46200
horizontal
vertical
46150
46100
counts
counts
55000
46050
46000
45950
45900
0
50
100
150
200
250
300
sample
"Data contained herein is exempt from ITAR regulations under CFR 125.4(13) -- data approved for public disclosure."
February 21, 2002
TIPS meeting
21
CONCLUSIONS
FPA 31 has been deeply investigated
• QE above Performance Specs at λ>1.35µm
below Minimum Specs at λ<1.2µm
• Dark Current meets specs by a factor ~4, but
– Needs ~ 36hr to settle
– Irregular behavior common for short exposure times
•
•
•
•
•
OK
NO
??
NO
NO
RON ~30 electrons/read
Linearity and well depth
Amplifier glow
Cosmetic
Reference pixels
OK
OK
OK
OK
"Data contained herein is exempt from ITAR regulations under CFR 125.4(13) -- data approved for public disclosure."
February 21, 2002
TIPS meeting
22
• One between FPA#31 or FPA#33 to be delivered next
week
• Rockwell has produced two extra non-flight parts,
FPA#35, #36 currently under test. Preliminary data
confirm QE and RON measured at DCL.
• Rockwell has delivered to UH (D. Hall) a detector with
5µm material and HI-1R MUX for RON test.
• Rockwell has agreed to grow LOT 5. Expected 6-8 weeks
for PECs/test device data and 4 months for flight parts.
• Contractual issues worked on.
• New plan for 2nd detector build under discussion with
BALL.
"Data contained herein is exempt from ITAR regulations under CFR 125.4(13) -- data approved for public disclosure."
February 21, 2002
TIPS meeting
23
MEMORANDUM
TO:
Distribution
DATE:
February 21, 2002
SUBJECT:
Questions and Answers from the 21 February 2002 TIPS Meeting
SISD Perspective
Presenter – Harry Ferguson
No questions.
Cycle 11 Update and Cycle 12 Plans
Presenter – David Soderblom
Q: Is there any change to the SM3b launch date?
A: There is no change.
WFPC2 Status
Presenter – Anton Koekemoer
Q: Will the Dither Working Group work on a release of the meta-drizzle tool and make it available to the
user community?
A: The Dither Working Group plans to discuss the specifications for future drizzle software, and metadrizzle is on the discussion list.
Comment: The issue and information regarding the study of the WFPC2 filter wheel rotation anomaly
have been disseminated to the WFC3 community.
Q: Could other shifting anomalies, such as the jitter shifting, be caused by the filter wheel rotation
anomaly?
A: It is possible, and we will need to investigate this further.
ACS Flat Fields
Presenter – Ralph Bohlin
Q: Why would the structures seen on the ACS WFC flat fields go across from one chip to the other?
A: The two detector chips were split from the same whole chip and were matched back, and so one would
expect to see flat field structures to cross from one chip to the other.
Q: What are the other faint circular structures seen on the flats?
A: Those are dust particles on the window, and the magnitudes of those are less than 1%, which will not be
of significant impact.
Q: How reproducible are the flat fields and are there significant variations?
A: The flat fields are highly reproducible, and variations are less than 1%.
1
Q: Regarding the filter shift problem, one would expect the linear ramp filters to be more problematic.
Have flat fields been taken for those filters?
A: No, as long as the dust contamination is not larger than expected, we do not anticipate any problem with
the flats. Actual science data might have problems, though.
Q: Given that the data from the resolver can determine the filter wheel’s offset, could we implement a fix
in the calibration pipeline?
A: It is possible, but there is no current plan to pursue this.
WFC3 Status (Detectors)
Presenter – Massimo Robberto
Q: What is the implication of the measured persistence value for the IR detectors?
A: The measured persistence is simply the dark current as measured 96 minutes after the illumination, and
it does not provide insights to cosmic-ray persistence issues.
2