TIPS/JIM
May 17, 2012
Agenda:
INS Division News (John MacKenty) with Tom Brown on JWST
A New Photometric Correction Formula for ACS (Marco Chiaberge)!
ITSD Reorganization (Marty Durkin)!
FGS CVAC Test Results (Pierre Chayer)!
Next TIPS/JIM: June 21, 2012
JWST NEWS
•
Geoff Yoder is replacing Rick Howard as JWST Program Director at NASA HQ
•
MIRI should be delivered to GSFC on May 29
•  MIRI detector analysis proceeding in parallel at JPL
•
FGS+NIRISS should be delivered to GSFC by the end of July
•
NIRCam will be in I&T this summer, with a significant staffing contribution from STScI
•
The Project is currently working to recover mass margins by exploring various options
TIPS/JIM
May 17, 2012
Agenda:
INS Division News (John MacKenty) with Tom Brown on JWST
A New Photometric Correction Formula for ACS (Marco Chiaberge)!
ITSD Reorganization (Marty Durkin)!
FGS CVAC Test Results (Pierre Chayer)!
Next TIPS/JIM: June 21, 2012
A NEW CTE PHOTOMETRIC
CORRECTION FORMULA FOR ACS
Marco Chiaberge
TIPS meeting 05/16/2012
CHARGE TRANFER EFFICIENCY (CTE) per pixel
Defined as CTE = 1 - ΔQ/Q = 1 - CTI
For an ideal CCD CTE = 1.0
For real CCDs CTE < 1
Manufacturing imperfections in the crystalline lattice
Radiation damage (increasing with time)
CTE on ACS was not 1.0 at lunch!
The total CTE is CTEN
significant effect for large CCDs
CTE depends on flux, sky level, # of transfers
The effect of CTE on stellar photometry
is to reduce the measured flux
A significant fraction (all?) of the “lost” flux
goes into the “tail”
Timeline of ACS CTE corrections
Time dependent formula based on 3 epochs
March 2003 – Feb 2004
Riess & Mack ISR 2004-006
Revised formula Chiaberge et al. ISR 2009-01
New approach for data analysis, 4 epochs
Increased accuracy
Δmag = 10A • SKYB • FLUXC • Y/2000 • (MJD-52333)/365
Linear in log Δmag v log flux and log sky!
Anderson & Bedin 2010 pixel-based CTE correction
Included in the new CALACS
WHY DO WE STILL NEED A
PHOTOMETRIC CORRECTION FORMULA?
We need to keep monitoring the time dependence
and make sure that photometry is correctly recovered
Some users may prefer to use a correction formula.
The correction formula may be more accurate for some
regions of the parameter space
What should we use for extended sources?
Photometric test
D
C
Y1
B
A
Y2
Y Transfers=ΔY=Y1-Y2
WFC
For y=1024
ΔY=0
Δmag=0
Post-SM4 Observations
Programs: CAL/ACS 11880, 12385, 12730
FILTERS:
F606W, F502N
EXP TIMES: Between 30s and 400s
5 Background levels
between ~0.1 and 40eLow sky
CR-REJECTION, no dithering
1 epoch/cycle
Target: 47 Tuc (7’ off center)
Cycle 19: + pointing 3’ south of 47Tuc center for the lowest sky level
9 external orbits
47 Tuc 7’ off center
~ 2000 stars
47 Tuc 3’ off center
~ 7000 stars
ANALYSIS PROCEDURE
(semi-automatic, thanks to Pey Lian!)
•  1 Generate “clean”, deep, drz image using all data
•  2 Identify saturated pixels and mark them
on the DQ extension of FLT files
•  3 Mask out area around the saturated stars
•  4 Find stars on the deep mosaic, then measure flux of all stars
that are detected on (both of) the single_sci files (aperture phot)
•  5 Fit Δmag vs # of transfers for different bins of flux
(rejecting outliers with iterative sigma clipping)
•  6 Find the best fit model parameters to reproduce the
dependence of Δmagy=2000 on Sky and Flux levels
F502N 30s November 2011
A linear fit is performed
for each bin of flux
(red lines)
Rms errors on the slope
are estimated
(yellow lines)
At y = 2000
Mag loss of 0.56 ± 0.07 mag
CTE Correction formula assumed dependence on flux
Δmag = 10A • SKYB • FLUXC • Y/2000 • (MJD-52333)/365
2 problems:
Cycle 17
Cycle 19
Y=2000
CTE improves at low
Signal levels???
0.6 e0.3e-
32e-
Large deviations from
the assumed linear dependence
Photometry with different detection thresholds: 3 and 10σ
BUT THIS IS WHAT USERS NORMALLY DO!
Average flux I measure in that bin
Δmag
N
50e-
Far from amplifiers
100e-
Flux
Close to amplifiers
Detection threshold
CTE Correction formula assumed dependence on flux
Δmag = 10A • SKYB • FLUXC • Y/2000 • (MJD-52333)/365
Cycle17
19
Cycle
0.6 e0.3e-
32e-
Much better represented by a linear relation in Δmag v Log sky
Cycle 19
Δmag = α Log flux + β
α,β = α(sky), β(sky)
0.6 e14e-
Δmag = [α Log(flux) + β] • y/2000
α = p Log(sky) + q
β = p’ Log(sky) + q’
Δmag = p Log(sky) Log(flux) + q Log(flux) + p’ Log(sky) + q’
p, q, p’, q’ = p(t), q(t), p’(t), q’(t)
Δmag = p Log(sky) Log(flux) + q Log(flux) + p’ Log(sky) + q’
p, q, p’, q’ = p(t), q(t), p’(t), q’(t)
Linear fit using “R”, for each epoch
The new time dependence does
not assume CTE = 1
at T = Tlaunch
T – Tlaunch (d)
Comparison with pixel-based CTE correction
CTE formula is more accurate than the pix-CTE correction
at the lowest background levels
RESULTS
• A new accurate CTE photometric correction formula is now available
• The accuracy is comparable to (or better than!) the pix-cte correction
• Does not depend on the assumption of CTE = 1 at T = Tlaunch
FUTURE WORK (from TIPS 2009)
•  New observations after SM4 using CR-REJ and possibly dithering
•  Procedures should be made automatic (or semi-automatic)
•  Formula for different aperture radii
•  Better data might lead to a better characterization
Different form of the formula?
FUTURE WORK
•  Better estimate of the errors on the coefficients
•  Formula for different aperture radii
•  Extended sources?
•  Webpage for correction
Thanks to Jay, Linda, Roberto and Pey Lian
Photometric test
Allows to measure the total flux lost and
provides correction formulae for photometry.
Stars are positioned at different distance from the readout
amplifier thus changing the number of transfers and therefore
the impact of CTE.
D
B
WFC
C
A
47 Tuc
F606W
40s exp
Long vs short: find stars in F606W 400s
Measure the flux of all stars in F502N 30s
in F606W 400s
i
No correction
Corrected
TIPS/JIM
May 17, 2012
Agenda:
INS Division News (John MacKenty) with Tom Brown on JWST
A New Photometric Correction Formula for ACS (Marco Chiaberge)!
ITSD Reorganization (Marty Durkin)!
FGS CVAC Test Results (Pierre Chayer)!
Next TIPS/JIM: June 21, 2012
Marty Durkin, Glenn Miller 5/17/2012 Goal of ITSD —  Provide outstanding customer service and IT tools to the user community to enable the Institute to meet its Mission, Science and Business goals. Feedback on ITSD —  We obtained input from: —  Our Customers: Meeting with Division Management, Director ‘s Office and Institute staff on their perception of ITSD —  ITSD Staff: Focus Group report from Dr. Fred Mael —  ITSD Management: Branch Managers analyzed work flow and issues within the Division —  What did we find from this feedback? —  ITSD does a tremendous amount of good work but there are areas where we need to improve. Focus Areas —  Areas we are focusing on to make ITSD more effective: —  Increase the role of the customer in how decisions are made and priorities are set —  Clear understanding of the roles and primary points of contact —  Streamline and simplify processes ITSD Approach Going Forward —  Build and maintain stronger relationships with our customers —  Receptive to new ideas and technologies —  Recognize the value of failing forward —  Build capable and adaptable teams Structural Improvements —  Streamline and clarify workflow through organizational changes —  Align the focus of the teams with customer needs —  Create Technical Lead & Chief Technical Lead roles —  Technical Leads are identified points of contact and will lead and coordinate work across the work units. —  Part of their role is to partner with the OED Chief Engineers in the relevant domains. ITSD Current Org Structure ITSD New Org Structure ITSD New OrganizaBon —  4 Branches —  Staff Desktop and OS Support Branch —
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Helpdesk (Val Ausherman) Desktop OS support (Jim Grice) —  Mission & Server Support Branch —  Mission support —  HST(Patrick Taylor) —  JWST (Matt Sienkiewicz) —  CMO (Ron Russell) —  SCIENCE (Tony Darnell) —  Servers (Phil Grant) ITSD New OrganizaBon (cont’d) —  4 Branches (cont’d) —  Infrastructure Support Branch —
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Network/VOIP (Gary Gladney) Security (Jamie Lipinski) Storage & Backups (Prem Mishra) Email & Calendaring (Greg Sachs) Database (Jeff Wagner) ITSD New OrganizaBon (cont’d) —  4 Branches (cont’d) —  Business, Applications and User Tools Branch —
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Business Tools (Joy Hale) Custom Applications (Joy Hale) A/V (Calvin Tullos) Documentation and Handbooks Web (Leigh McCuen) —  Branches will come up with final branch names. IT Services Division ReorganizaBon Next Steps —  Deploy new structure (4/9/2012) —  Finalize branch names (5/11/2012) —  Customer Service training (5/2012) —  Update and communicate IT roadmaps (6/2012) —  Define and advertise priorities of ITSD work and how this ties into the Institute’s mission. (6/2012) —  Reinforce values and behaviors (ongoing) What We Plan to Accomplish —  Our customers will view us as the IT source for enabling them to get their jobs done. —  Modern and innovative approaches and solutions are an integral part of the way we work. Assessment —  Metrics —  Response time to helpdesk requests —  Time to deliver new systems —  Meeting deliverables —  Number of new technology evaluations —  Customer Feedback TIPS/JIM
May 17, 2012
Agenda:
INS Division News (John MacKenty) with Tom Brown on JWST
A New Photometric Correction Formula for ACS (Marco Chiaberge)!
ITSD Reorganization (Marty Durkin)!
FGS CVAC Test Results (Pierre Chayer)!
Next TIPS/JIM: June 21, 2012
JWST FGS & NIRISS CVAC Tests
November 1, 2011 − January 25, 2012
Pierre Chayer, André Martel, Alex Fullerton, Ed Nelan,
Kevin Volk, Anand Sivaramakrishnan, Sherie Holfeltz,
Van Dixon, Paul Goudfrooij,
Deepashri Thatte, Harry Ferguson
Comdev Canada, CSA, UdeM, HIA
FGS: Fine Guidance Sensor
NIRISS: Near-InfraRed Imager & Slitless Spectrograph
2012 May 17
1
Fine Guidance Sensor (FGS) Optical Layout
Role of FGS: Provides centroids
to the Attitude Control System.
Pick-Off Mirror
Focus Mirror
Detectors
100 mm
TMA Mirrors
2m
2012 May 17
2
FGS Optical Assembly
2012 May 17
3
FGS at the David Florida Laboratory
2012 May 17
4
FGS entering chamber
2012 May 17
5
FGS Optical Assembly
2012 May 17
6
FGS in chamber
2012 May 17
7
Optical Ground System Equipment (OGSE)
2012 May 17
8
Optical Ground System Assembly (OGSE)
NIRISS
NIRISS
2012 May 17
9
Floor plan for CVAC test
2012 May 17
10
Temperature Profile
Slower
Cool-down
•
~80K
Plateau
moved up
•
•
3x 37 K
Plateaus
100
~80 K
40.5 K Plateau
Extended
40.5 K
Plateau
Normal
warm-up
37 K # 1
37 K # 3
37 K # 2
22 K Survival
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47
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63
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69
71
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85
•
CVAC Temperature Summary
Temperarure (K)
•
Test Day
FGS A verage
2012 May 17
Thermal Strap
KM A verage
IP A verage
TV3 Chamber A verage (K)
GHe A verage
11
Chamber background
2012 May 17
12
Location of OGSE Spots in G1
2012 May 17
13
Images of OGSE Sources
2012 May 17
14
Bad Pixel Maps
2012 May 17
15
IDENTIFICATION
•
•
•
•
•
•
•
•
•
Identification of the Guide Star.
Full-frame: strip readout: 36 (64x2048) strips, 8 overlaps.
ID strip integration time: 0.32 sec.
Strip readout: read-read-reset-read-readè CDS1 and
CDS2.
Create two lists of bright objects.
Merge the two lists è one list.
Identify guide star and ref. stars è Triad algorithm.
Success è Guide star is identified.
ID timing: 82.12 sec, G1, 5 stars, 8 candidates.
2012 May 17
16