TIPS-JIM Meeting
21 September 2006, 10am, Auditorium
1.
ACS Side-1 Anomaly Review Board
Conclusions
Ken Sembach
2.
Spectrophotometric Calibration of
Ralph Bohlin
NICMOS and Application to JWST Standards
3.
Calibrating a CVZ Astrometric Field in
the LMC with ACS for JWST
Rosa Diaz-Miller
Next TIPS Meeting will be held on 19 October 2006.
ACS Side-2 Performance Update
STScI TIPS Meeting
20-July-2006
Ken Sembach
1
ACS Timeline
Date (2006)
Event
June 19
ACS suspends at 17:15 UTC. Tiger Team formed.
June 20
ACS Suspend Status Meetings start.
Analysis of ACS data prior to suspension shows that it looks normal.
SMOV preparations begin in case switch to Side-2 is necessary.
June 21
ACS CEB Anomaly Review Board created.
June 22
Observing timeline intercepted with SMS containing no ACS activities.
Tiger Team passes off investigation to ARB.
ACS transitioned to Operate mode on Side-1 as recommended by TT.
June 23
ACS Team decides to recommend WFC temperature setpoint change.
June 27
ARB recommends switch-over to Side-2.
ARB endorses WFC temperature setpoint change.
June 29
FRR for switch-over to Side-2 held - Switch-over approved.
New FSW uploaded to ACS.
June 30
Uplink and realtime switch to Side-2. CCD electronics boards powered.
ACS safed for SMS intercept on July 2.
2
ACS Timeline (continued)
Date (2006) Event
July 2
Intercept of SMS with ACS activities.
July 3
Successful checkout of ACS memory / dumps.
July 4
WFC temperature setpoint lowered from -77 C to -81 C.
Successful resumption of CCD calibration and science observations.
July 7
ARB lifts moratorium on SBC observations.
ARB considers risks/benefits of ACS Side-1 testing.
July 11
ARB votes that risks to ACS assets outweigh benefits of Side-1 testing.
July 12
Press release for first Side-2 science observation released.
July 13
HST Project concurs that Side-1 tests should not be done at this time.
July 16
SMS contains SBC SMOV activities.
July-August Analysis of SMOV / science data in progress.
3
ACS Suspends
• What was observed
• All ones were read back from WFC and HRC CCD Electronics Box
(CEB) A/D telemetry FIFOs
• Status buffer messages : +15V and +5V supply voltages at high limits
• 36 CEB limit-checked parameters were found to be out-of-limits
• ACS current decreased 1.2-1.8 amps (no current spike in ACS)
• Anomaly lasted about 7 seconds before ACS suspended
• Ruled out
•
•
•
•
WFC and HRC CEB interface optocouplers in common package
WFC and HRC CEB FIFO read control
CEB A/D converters
Space weather-induced damage (excessive radiation)
4
CEB Power Switching
All relays independent and switched by individual RIU commands
LVPS1
ASPC1
(video)
MEB2
ASPC2
(video)
Clock1
(CCD control)
MEB1
LVPS2
Clock2
(CCD control)
Timing
(main control)
CEB
All boards are needed for operation of the entire detector.
Single fault affects at most half the science data.
One CEB each for WFC and HRC
Simplified – multiple diode
busses in hardware
Legend:
5V only
5
Anomaly Review Board Investigated Possible Failures
Case
#
Failure Mode
Anomaly
match
based on
ETU
testing
Implicates
Expected Telemetry
+5V
+15V
-15V
+35V
+5V
+15V
-15V
+35V
1
All Nominal
No
Problem intermittent or
+15V open beyond TLM
sample point
2
+15V open
(external)
YES
LVPS #3 Board
+5V
0V
-15V
0V
3
+15V open
(internal)
YES
MFL2815D
+5V
0V
-18V to
-20V
0V
4 or 5
6
7
8 or 9
-15V open
(external or
internal)
+15V
shorted
(internal or
external)
-15V shorted
(internal or
external)
No
MFL2815D or LVPS #3
+5V
+15V
0V
+35V
YES
MFL2815D or LVPS #3 or
MEB Backplane or
Harness to CEBs
+5V
0V
-6V to
-8V
0V
No
MFL2815D or LVPS #3 or
MEB Backplane or
Harness to CEBs
+5V
+8V to
+11V
0V
+30V to
+35V
MFL2815D
inhibited or
internally
destroyed
No
(additional
testing in
progress)
MFL2815D
+5V
0V
0V
0V
Fault within MFL2815D
Fault on LVPS #3 Board, not in MFL2815D
Fault mode matches on orbit anomaly signature
6
ACS Resumes Exploration of the Universe
7
ACS Side-2 Orbital Verification Programs
Program
Analysis
10735
Cox
SBC MAMA Recovery
4 (I)
10737
Mack /
Gilliland
CCD Stability Monitor
5 (E)
10738
Program Name
Mack /Bohlin Earth Flats
10752
Sahu / Lallo
11005
Sirianni /
Lucas
11006
Cox
11007
Welty
11008
Sirianni
11009
Welty
Orbits
2 (I)
Cycle 14 Focus Monitor
1 (E)
Functional Test - MEB2 Switch
35 (I)
SBC Filter Wheel Checkout
7 (I)
ACS Side 2 Dump Test and Verification of ACS
Memory Load
1 (I)
ACS CCDs Side-2 Temp Setpoint
4 (I)
ACS Science Data Buffer Check/ Self-Tests for
CS Buffer RAM and MIE RAM
8 (I)
8
ACS WFC Temperature Setpoint Change
• HRC TEC setpoint maintained at -80 C
• WFC TEC setpoint lowered from -77 C to -81 C after Side-2 switch
• Lower WFC setpoint should improve science
• 2005 Aft Shroud Cooling System study
• Fewer hot pixels (and fewer anneals needed)
• Shorter charge transfer tails
• Gain in sensitivity for deep exposures is ~ 0.1 magnitudes (or
equivalently, about 20% in observing time)
• Lowering temperature now consolidates recalibration activities for
Side-2 switch and temperature change
• Change would likely have been needed within the next 12-24 months
9
Dark Current / Hot Pixels
WFC1
Side-2 (-81 C)
Side-1 (-77 C)
WFC2
Side-2 (-81 C)
Side-1 (-77 C)
Note: The white histogram is wider because only 4 images were used instead of 40. In both cases the tail of the
histogram is for 1 single day, the first day after the anneals of July 14 (white) and June 15 (yellow).
WFC1
WFC2
Dark Current: (e/pix/hr)
Side-2 (-81 C)
Side-1 (-77 C)
10.2
18.4
8.6
15.7
Ratio
(-81 C / -77 C)
0.55
0.55
10
WFC Hot Pixel Contamination (%)
Threshold
(e-/pix/sec)
Side1
(-77 C)
Side2
(-81 C)
(-81C /-77C)
>0.01
22.2
9.0
0.41
>0.04
3.8
1.3
0.34
>0.08
1.6
0.6
0.37
>0.10
1.1
0.5
0.45
Ratio of Hot Pixels (-77 C / -81 C)
Ratio
Side-1 (-77 C)
Side-2 (-81 C)
Note: 100x80 pix region, first day after annealing (only pixels brighter than 0.08 are shown)
11
Gain Ratio
• WFC: Gain=1 and Gain=2 (default)
• Side-2 Ratio
• Same as on Side-1 to 1 part in 104 (47 Tuc data)
• Quad-quad gains are consistent to 1 part in 103
(internal flats)
12
WFC Bias Jumps
A
Typical case
A
B
B
1 DN
C
C
D
D
Image stretched to show bias jumps.
1 DN
13
WFC Bias Jumps
A
Worst case
A
B
B
1 DN
C
C
D
D
Image stretched to show bias jumps.
1 DN
14
WFC Bias Jumps
• WFC
• Side-1 (Gain=2, default)
• Jump detected in 1/40 images
• Jump detected only on Amplifier B
• Side-2 (Gain=2, default)
• Jump detected in 7/35 images
• Jump detected on 2 or 4 amplifiers simultaneously
• Side-2 (Gain=1)
• Jump detected in 5/35 images
• Jump detected only on 1 amplifier at a time, mostly Amp B
• HRC
• No bias jumps observed on Side-1 or Side-2
15
Sensitivity
• Small sensitivity decrease
(expected) seen after lowering WFC
setpoint
• Sensitivity measured using stellar
photometry and internal flatfields
Filter
Gain
Side-2 Change in QE
F435W
2
F475W
2
-2.1%
F606W
1,2
-1.2%
F625W
2
-0.9%
F775W
2
-1.1%
F814W
1,2
-2.6%
-1.1%
-2.2%
(Internal)
-1.7%
(Internal)
A 4096x4096 composite WFC/F606W image of a
portion of globular cluster 47 Tuc obtained on
Side-2 (4 x 339 sec).
16
Point Spread Function
•Astrometric and photometric analysis of WFC Side-2 47 Tuc data (J. Anderson)
• Temporal change noted was well within normal orbit-orbit and epoch-epoch ranges
• No evidence for additional underlying spatial dependence of PSF
Constant Library
Library + Perturbation
Empirical library PSF
for WFC/F606W
On average, 22.4% of light falls in
central pixel (+15%, -12%)
-1
+3
-1.0
-5
+1
-0.5
+6
+2
+0.3
+7
+3
+0.5
% Residual
Photometry
supported
to 0.005
mag
Astrometry
supported
to 0.01 pix
in
both x and y
Same as
on Side-1
17
Mechanisms Affected by Side-2 Switch
• Fold mirror / cal door / coronagraphic spot
• Resolvers and electronics
• Positions are within usual ranges seen for Side-1 motions.
• Filter wheels
• Resolvers and electronics
• Filter Wheel #1: positions are the same as on Side-1
• Filter Wheel #2: currently a small offset w.r.t. Side-1 (investigating)
• Shutter
• LEDs, photodiodes, and electronics
• No test performed yet
• Post-flash illumination
• LED
• No test performed yet (low priority)
18
Coronagraphic Spot Position
Side-2
Motion on Side-2
is well within
historical Side-1
envelope of positions.
19
NICMOS SPECTROPHOTOMETRY
R. Bohlin
06Sep21
1. Review non-linearity
2. Primary, secondary standard stars
3. JWST standard star program
REFERENCES
Grism Sensitivities and Apparent Non-Linearity, R. C. Bohlin, D.
Lindler, & A. Riess 2005, Instrument Science Report, NICMOS
2005-002, (Baltimore:STScI)
NICMOS Count Rate Dependent Non-Linearity in G096 and
G141, Bohlin, R. C., Riess, A., & de Jong, R., 2006, Instrument
Science Report, NICMOS 2006-002, (Baltimore:STScI)
*ISRs @ http://www.stsci.edu/hst/nicmos/documents/isrs
Bohlin, R. C. 2007, in The Future of Photometric,
Spectrophotometric, and Polarimetric Standardization, ASP Conf.
Series, Vol. xxx, ed. C. Sterken, "HST Stellar Standards with 1\%
Accuracy in Absolute Flux", also Astro-Ph 0608715
Calibrating a CVZ Astrometric
Field in the LMC with ACS for
JWST
Rosa I. Diaz-Miller
Space Telescope Science Institute
September 21st, 2006
TIPS Meeting
Astrometric Field in the LMC with ACS for JWST
◆
•
•
•
•
•
Collaborators:
Jay Anderson (Rice University)
Ralph Bohlin (STScI)
Stefano Casertano (STScI)
Jerry Kriss (STScI)
Matt McMaster (STScI)
Sep 21st, 2006
•
•
•
•
Massimo Stiavelli (STScI)
Vera Platais (STScI)
James Rhoads (UA)
Jeff Valanti (STScI)
Rosa Diaz-Miller
Astrometric Field in the LMC with ACS for JWST
◆
◆
◆
Rationale for Cross Calibration of JWST
Strategy for securing an astrometric field
Preliminary results
Sep 21st, 2006
Rosa Diaz-Miller
Rationale for Cross Calibration
◆
HST astrometric observations are essential for calibrating
JWST field distortion.
➥ Meet JWST calibration requirements
Field distortion correction within any instrument and guide
star shall not exceed 0.005 arcsec RMS
➥ This will enable the precise target positioning required for
multi-object spectroscopy with NIRSpec.
➞ MSA: (750 x 350) shutters, each (200 x 450) mas2
➥
➥ Enable higher quality science early in mission.
◆
JWST self calibration?
o
➥ JWST
roll angles at one time +/- 5
➥ JWST will need more than 60 days to attempt good self
calibration of an astrometric field.
➥ Changes in stability of JWST’s mirror might have smaller
time scales.
Sep 21st, 2006
Rosa Diaz-Miller
Astrometric Field in the LMC with ACS for JWST
◆
Added Advantages of HST-JWST cross calibration:
➥ Save JWST observing time
➥ External check on JWST astrometric solutions
➥ HST/ACS field with astrometric precision better than can likely be
obtained from JWST alone.
◆
How well can ACS do?
➥ Arbitrary ACS-WFC fields can achieve 5 mas accuracy.
➥ Errors less than 2 mas are possible with proper distortion correction
using multiple roll angles. Current distortion correction => 0.01 pixels
and 0.01 mag accuracies for ACS/WFC (Anderson & King 2000,
2003,2006)
Sep 21st, 2006
Rosa Diaz-Miller
Astrometric Field in the LMC with ACS for JWST
◆
Astrometric-calibration field for JWST:
➥ High stellar density
➥ Most stars usable
➥ Stellar density variation < 2
➥ Separation ~10 FWHM
➥ S/N ~ 100 at V=24
➥ Small proper motions
➥ Field in the JWST CVZ
Sep 21st, 2006
Rosa Diaz-Miller
Astrometric Field in the LMC with ACS for JWST
◆
LMC is ideal. About 10 stars per 3.75x3.75 arcsec2
C. Smith, S. Points,
the MCELS Team and
NOAO/AURA/NSF
Sep 21st, 2006
Rosa Diaz-Miller
Astrometric Field in the LMC with ACS for JWST
◆
Astrometric Calibration Strategy to get errors < 2 mas
◆ Multiple dithered observations of the same field and
different roll angles
➥ ACS-WFC filter F606W
➥ Mosaic of images to cover
a 5.4x5.4 arcmin2 region.
➥ 5 fields, 60” apart
➥ 6 points dither pattern per
field with steps of ~3-10
arcsec
➥ Large dynamic range
➥ Two roll angles separated
by 75o
➥
30” dithers
Sep 21st, 2006
Rosa Diaz-Miller
Astrometric Field in the LMC with ACS for JWST
◆
Correcting for distortion
➥ Use PSF library to
determine position of each
star (Anderson & King
2005, PASP, 115, 113;
ACS ISR 2006-01)
➥ Measure all the stars in
each image.
➥ Solve for the distortion
coefficients fitting the
residuals with fourth-order
polynomials
➥ Cross identify stars in the
various images.
Anderson, J. 2005, HST Calibration Workshop
Sep 21st, 2006
Rosa Diaz-Miller
Astrometric Field in the LMC with ACS for JWST
◆ First orientation: 30 exposures
◆
About 100,000 bright enough stars in the field. (J. Anderson)
Composite
image
Sep 21st, 2006
Close up
Rosa Diaz-Miller
Astrometric Field in the LMC with ACS for JWST
Identified stars in each field (field P1 in red, P2 in blue, P3 green, P5 magenta)
Close-up
Sep 21st, 2006
Rosa Diaz-Miller
Astrometric Field in the LMC with ACS for JWST
◆RMS
residuals for first orientation fields.
◆ PSF blurrier than library ( ~10% less flux in the core.)
◆
Current accuracies ~0.03-0.02 pixels
Sep 21st, 2006
Rosa Diaz-Miller
Astrometric Field in the LMC with ACS for JWST
RMS residuals along x
axis for field P1
Sep 21st, 2006
Rosa Diaz-Miller
Astrometric Field in the LMC with ACS for JWST
◆
RMS residual along Y axis for field P1
Sep 21st, 2006
Rosa Diaz-Miller
Astrometric Field in the LMC with ACS for JWST
◆
RMS residuals are derived from 6 dither pointings with
the constrain that a star should be at least in 5 of the 6
pointings
➥ Since we have large dithers => in this analysis we are missing
some stars.
➥ Need to change this constrain
➥ Need to add the short exposure
◆
After all geometric distortions have been removed from
the 5 fields, we are still left with a distortion that has
scales of about 1000 pixels. We need to remove this
distortion.
Sep 21st, 2006
Rosa Diaz-Miller
Astrometric Field in the LMC with ACS for JWST
AVG= 30 pointings
Sep 21st, 2006
Rosa Diaz-Miller
Astrometric Field in the LMC with ACS for JWST
AVG= 30 pointings
Sep 21st, 2006
Rosa Diaz-Miller
Astrometric Field in the LMC with ACS for JWST
RMS residuals for master frame (average of 30 pointings)
Sep 21st, 2006
Rosa Diaz-Miller
Astrometric Field in the LMC with ACS for JWST
RMS residuals for master frame (average of 30 pointings
Sep 21st, 2006
Rosa Diaz-Miller
Astrometric Field in the LMC with ACS for JWST
◆
Second orientation: 12 pointings
➥ Stars well fit by the empirical PSF library
➥ Internal consistency with which we are
measuring positions and fluxes is better than
0.01 pixel and 0.01 mag
➥ We need to compare with first orientation
Sep 21st, 2006
Rosa Diaz-Miller
Astrometric Field in the LMC with ACS for JWST
◆
Summary
➥
First orientation: 30 pointings
➞ Current accuracies ~0.03-0.01pixels
➞ Re-derive PSF library?
➞ Add short exposures.
➞ Find extra correction to the distortion.
➥
Second orientation: 12 pointings
➞ Stars very well fit by my empirical library PSF
➞ Compare with first orientation
➥Expect
to get accuracies to 1mas (0.5 mas)
➞ Need to remove extra distortion first
Sep 21st, 2006
Rosa Diaz-Miller