PACS ICC Readiness Review MPE, July 3/4 2008 PACS Photometer PV Phase Plan 1 Status Report M....

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)


MPE, July 3/4 2008 2


• 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


MPE, July 3/4 2008 3


• 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


MPE, July 3/4 2008 4


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


MPE, July 3/4 2008 5


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


MPE, July 3/4 2008 6


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


MPE, July 3/4 2008 7


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


MPE, July 3/4 2008 8


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)


MPE, July 3/4 2008 9


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


MPE, July 3/4 2008 10


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


MPE, July 3/4 2008 11


Test Block: AOT validation (fully defined) 137.1 hours

• covered in talk by T. Müller


MPE, July 3/4 2008 12


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


MPE, July 3/4 2008 13


Calibration sources


- celestial pointing star coverage (ecliptic coordinates)


MPE, July 3/4 2008 14


Calibration sources


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


MPE, July 3/4 2008 15


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

PACS ICC Readiness Review MPE, July 3/4 2008 PACS Photometer PV Phase Plan 1 Status Report M....

Documents

Transcript of PACS ICC Readiness Review MPE, July 3/4 2008 PACS Photometer PV Phase Plan 1 Status Report M....