Calibrating the PAU Surveys 46 Filters Anne Bauer IEEC/CSIC - - PowerPoint PPT Presentation

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Calibrating the PAU Surveys 46 Filters Anne Bauer IEEC/CSIC - - PowerPoint PPT Presentation

Dec 20, 2022 252 likes •437 views

Calibrating the PAU Surveys 46 Filters Anne Bauer IEEC/CSIC Barcelona P hysics of the A ccelerating U niverse William Herschel Telescope 4.2m, 40 unvignetted field of view Data acquisition to start in 2013 PAUCam is being

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SLIDE 1

Calibrating the PAU Survey’s 46 Filters

Anne Bauer IEEC/CSIC Barcelona

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SLIDE 2

Physics of the Accelerating Universe

  • William Herschel Telescope 4.2m, 40’ unvignetted field of view
  • Data acquisition to start in 2013
  • PAUCam is being designed, built, and tested in Barcelona and Madrid
  • 18 CCDs

8 central, 10 boundary (vignetted)

  • 6 broad band + 40 narrow band filters

ugriZy + 100Å-wide filters from 4500-8500Å

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SLIDE 3

PAU Survey Goals

  • On the order of 100-200 square degrees
  • Depth ~24.5 in broad, 23.5 in narrow bands
  • Narrow bands give a low-resolution spectrum

→ photo-z accuracy of 0.0035(1+z) for 70%

  • f all imaged galaxies.
  • Main goals: galaxy correlations with good 3D precision
  • Redshift space distortions
  • Weak lensing magnification
  • Photometric-spectroscopic cross-correlations (e.g. DESpec)

0.2 0.4 0.6 0.8 1 3000 4000 5000 6000 7000 8000 9000 10000 11000 Angstroms

see Gaztañaga et al. http://arxiv.org/abs/1109.4852

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SLIDE 4

PAU Data Management

data centre

Nightly Processing Pipeline

data arrival

Data Monitor

Multi-band & Multi-epoch

to science

Pixel Simulation Pipeline Analysis Pipeline RAW Level 1 products

Data Base

Level 2 products

Storage

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SLIDE 5

Nightly Pipeline Overview

Exposure Loop

Parallel processing Loop

Night Loop

Serial processing Loop

Master BIAS Master FLAT Cosmetics MASK Image MASK + Weight MAP (CR+Cosmetics+Sat) Source Extraction 2 + Photometric Calibration Clean Image Detrending & Masking Calibrated header + PSF model

SExtractor - SCAMP SExtractor

Catalogue Ingestion

DETECTION Objects

REDUCED set

Data Base

REMAP set

Source Extraction 1 + Astrometry

Remapping

Image REDUCED + Image MASK + Weight MAP

Precomputed mosaic solution

[.ahead]

Instrumental Calibration Initialization

RAW Science

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SLIDE 6

Nightly Pipeline Calibration Strategy I

  • Broad band filters (ugriZ) can be calibrated against existing data (SDSS,

CFHT) with “small” color terms

  • Each filter tray contains broad filters; use the broad band calibration to

determine the observation' extinction (ZP)

  • Extrapolate ZP to narrow bands
  • Simple, straightforward
  • How accurate is the λ extrapolation?
  • Only possible for photometric data
  • Correlation of photometric errors on a

filter tray

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SLIDE 7

Nightly Pipeline Calibration Strategy II

  • Create a standard catalog in PAU filters
  • Fit standard catalog’s colors to stellar

spectral templates (e.g. Pickles), use the best-fit template to extrapolate the standard catalog to all PAU filters

  • Calibration errors less correlated across

the filter tray

  • Possible with non-photometric data
  • Dependent on the accuracy of the stellar templates
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SLIDE 8

Nightly Pipeline Calibration Strategy II

  • Create a standard catalog in PAU filters
  • Fit standard catalog’s colors to stellar

spectral templates (e.g. Pickles), use the best-fit template to extrapolate the standard catalog to all PAU filters

  • Calibration errors less correlated across

the filter tray

  • Possible with non-photometric data
  • Dependent on the accuracy of the stellar templates

Do both strategies Use agreement as a test (poor template match, bad weather)

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SLIDE 9

Nightly Pipeline Calibration Status

  • Strategy II implemented as default
  • Diagnostic plots show ZP λ-dependence
  • Tested using the Pixel Simulation
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SLIDE 10

Multi-Epoch Calibration Strategy

  • We will have ≥2 observations in each filter
  • Übercalibration: find ZPs that minimize the photometric offset between
  • bservations over the same area, in the same filter

Data Base DETECTION Objects DETECTION Objects GLOBAL Objects

übercalibration MEMBA Pipeline Photometric ZPs for coaddition

Upon Request

position matching

Data Base

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SLIDE 11

Multi-Epoch Calibration Strategy

  • Übercalibration recalibrates the magnitudes, not colors
  • Color refinements / checks
  • Insist on main sequence colors (many-D color space!)
  • Spectrophotometric standards
  • Not yet implemented

From SDSS EDR

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SLIDE 12

Pixel Simulation Overview

Exposure Exposure Exposure Exposure Environmental Conditions model

...

Observation request

Survey Strategy model targets

SkyMaker

Catalogue Factory Post-Production Real Bright Star Catalogues

SDSS

Model Faint Star Catalogues

Besançon

Mock Galaxy Catalogues

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SLIDE 13

Pixelsim Example Outputs

  • Need to make it dirty!
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SLIDE 14

Pixelsim Example Outputs

  • Implementing PSF distortions...
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SLIDE 15

Pixelsim Example Outputs

  • Implementing PSF distortions...
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SLIDE 16

Calibration Testing status

  • Current status:
  • Nightly pipeline runs on PC and GRID, with SQLite or Postgres DB
  • “Default” Sextractor configuration with MAG_AUTO gives ≲1% error (with

pretty data)

  • Immediate goals:
  • Test photometry’s robustness to, e.g., PSF variations, template uncertainties
  • Evaluate choices in survey strategy
  • Longer term goals:
  • Run end-to-end data analyses to test propagation of errors onto

cosmological parameters

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SLIDE 17

The PAU Data Management Team

Anne Bauer Christopher Bonnet Ricard Casas Francisco Castander Martin Crocce Samuel Farrens Pablo Fosalba Enrique Gaztañaga Stephanie Jouvel Santiago Serrano Eusebio Sanchez Nacho Sevilla Jorge Carretero Josep Flix Christian Neissner Pau Tallada Nadia Tonello Marino Maiorino Pol Martí Ramón Miquel Carlos Sanchez