pacs icc readiness review mpe, july 3/4 2008 pacs photometer pv phase plan 1 status report m....
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PACS ICC Readiness Review
MPE, July 3/4 2008
PACS Photometer
PV Phase Plan
1
Status Report
M. Nielbock: PACS PHOT PV Phase Plan
Markus Nielbock (MPIA)
PACS ICC Readiness Review
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M. Nielbock: PACS PHOT PV Phase Plan
• PACS Calibration Document (PCD, PACS-MA-GS-001) is the compendium
‐ contains detailed description of all calibration requirements (pre and in flight)
‐ dedicated measurement and analysis plans for each aspect (CIPs, CAPs)
‐ serves as main reference for calibration measurement planning (CUS scripts)
• currently ~125 calibration requirements defined
• ground based FM-ILT as basis for definition and reference of in orbit calibration
PHOT blue detector
FOV distortion (PICC-ME-TR-006)
Example from FM-ILT:
PV Phase Plan document (PICC-MA-PL-001) is the immediate reference for planned PV calibration measurements and AOR configurations
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M. Nielbock: PACS PHOT PV Phase Plan
• PV Phase is preceded by Commissioning Phase
‐ FPG established
‐ final pointing accuracy reached
‐ functionality of mechanisms and detectors verified
• PV Calibration distributed across individual test blocks
‐ ordered according to calibration topics
‐ respects interdependencies and necessary pre-requisites
‐ provides coarse ordering for final time line
• PACS Photometer test blocks (fully defined → 345.1 hours = 14.4 days):
‐ Bolometer settings and characterisation (partly Commissioning Phase), includes read-out electronics, bias, responsivity, noise estimates, etc.
‐ FOV characterisation
‐ spatial calibration
‐ photometric calibration
‐ AOT validation
97.7 h = 4.1 d
3.6 h = 0.2 d
67.3 h = 2.8 d
13.5 h = 0.6 d
137.1 h = 5.7 d
‐ chopper angular calibration 6.0 h = 0.25 d
PV Phase only
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M. Nielbock: PACS PHOT PV Phase Plan
Test Block: Bolometer settings and characterisation (fully defined)
• PV part separated into three individual test blocks
• depends on results from Commissioning Phase (Steps I - III)
- Step IV: probes low gain performance (bias / responsivity) 11 hours
- Step V: probes high gain performance, depends on results from step IV 55 hours
- Step VI: compares direct and DDCS read-out modes depends on results from step V
32 hours
• complicates scheduling according to suggested PV time line
• sources: dark sky field, bright flux calibrators
- redistribution of ODs among instruments might be necessary
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M. Nielbock: PACS PHOT PV Phase Plan
Test Block: Verification of chopper angular calibration (fully defined)
• important for PHOT and SPEC
• blue PHOT used for observations: chopped measurements of double point sources with chop throw close to separation
• verification of on-ground angular calibration and spatial scale
6 hours
• sources: double stars, double galaxies, asteroid encounters (PACS-ME-TN-035)
2MASS Ks +IRAS/HIRES 60 μm
2MASS Ks +MIPS 70 μm
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M. Nielbock: PACS PHOT PV Phase Plan
Test Block: FOV characterisation (fully defined)
• assess the impact of straylight from and into the internal calibration sources
• accomplished by various full FOV scans with chopper
3.6 hours
• one FOV scan with CS switched off (requires modified set-up procedure)
• on dark sky field (~ 1 MJy/sr @ 100 μm) to minimise external contamination
IRAS 100 μm DSS
• optimise positioning of chopper on internal calibration sources
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M. Nielbock: PACS PHOT PV Phase Plan
Test Block: Spatial calibration (fully defined)
• FOV distortion
67.3 hours
- maps of bright sources at various chopper positions
- sources: bright isolated FIR sources
• PSF characterisation
- different observing modes
- sources: PSF standards with blue and red SEDs (stars, blazars, asteroids) to evaluate the influence of filter bandpass on PSF size
measured PSFblue detector
FM-ILT
- investigate scanning effect on PSF shape
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M. Nielbock: PACS PHOT PV Phase Plan
Test Block: Spatial calibration (fully defined) 67.3 hours
• also covers additional evaluation of electronic crosstalk and optical ghosts
• straylight from celestial sources
- scan maps of bright sources at varying chopper positions and scanning speeds
- scan maps around very bright source
- sources: preferentially planets (barely visible during foreseen PV period) isolated bright FIR sources (currently: IK Tau, 319 Jy @ 60 μm)
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M. Nielbock: PACS PHOT PV Phase Plan
Test Block: Photometric calibration (fully defined)
• provides the photometric characterisation (e.g. linearity) and absolute flux calibration
- standard point-source photometry (high and low gain)
13.5 hours
- sources: 8 prime fiducial stars, 55 asteroids, planets, 7 faint flux calibrators
from: Gordon et al. (2007), MIPS 70 μm calibrators
• complements optimisation of detector settings and frequent calibration on internal CSs
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M. Nielbock: PACS PHOT PV Phase Plan
Test Block: Photometric calibration (fully defined)
• issue to be traced carefully during telescope cool down:
• determines full system flat-field for blue, green, and red filters
- What are the best temperatures for the two internal calibration sources?
13.5 hours
- standard scan map on bright flux standard star
Flux ratio model: CS2 vs. telescope incl. stray light
- frequent monitoring of signal ratios between CSs and changing telescope background
- probably cannot be equally optimised for all filters compromise
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M. Nielbock: PACS PHOT PV Phase Plan
Test Block: AOT validation (fully defined) 137.1 hours
• covered in talk by T. Müller
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M. Nielbock: PACS PHOT PV Phase Plan
Calibration sources
• Photometric standards
1. prime fiducial flux calibrators (8 stars)2. Asteroids (55 well established, covering a large flux range)3. secondary flux standards (14 stars, 4 ULIRGs)4. faint flux standards (7 MIPS 70 μm stars from 22 mJy to 110 mJy)
• PSF standards (fiducial stars, asteroids, 13 blazars)
• Astrometric standards
1. initial alignment and FOV distortion: 36 bright FIR sources (stars, galaxies, PNe) from 80 Jy to 4810 Jy @ 60 μm (PICC-ME-TN-023)
2. pointing calibrators: 934 stars, 13 blazars, 17 QSOs and ULIRGs from 160 mJy to 187 Jy (PICC-MA-TN-003)
F(70 μm) [Jy] ≥ 10 ]10,5] ]5,1] ]1,0.5] ]0.5,0.16] total
single stars with photospheric emission 7 8 90 122 255 482
all stars 59 56 304 186 329 934
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M. Nielbock: PACS PHOT PV Phase Plan
Calibration sources
• Astrometric standards
- celestial pointing star coverage (ecliptic coordinates)
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M. Nielbock: PACS PHOT PV Phase Plan
Calibration sources
• Astrometric standards
3. spatial scale calibrators (separation ≤ 4’): for field distortion and angular calibrationa) FIR bright double stars (16 targets)b) FIR bright double galaxies (15 targets)c) asteroid-asteroid encounters (5 events during PV)d) asteroid-pointing star encounters (7 events during PV)
4. spatial scale calibrators (separation ≤ 2°): 92 pairs of pointing sources
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M. Nielbock: PACS PHOT PV Phase Plan
Summary
• PV calibration observations of PACS Photometer fully defined
• photometer characterisation analysis overhead might require redistribution of ODs
• final settings of internal CSs after frequent monitoring of telescope background
• full set of sufficiently suitable celestial calibration sources established
• some scheduling problems due to visibility constraints during model PV period
• AOR implementation already started (see talk by U. Klaas)
• planned PV observations provide full calibration of PACS Photometer