HARPS Data Flow System

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HARPS Data Flow System
HARPS-N PDR, 6-7 December 2007, Cambridge MA

• Christophe Lovis
• Geneva Observatory

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Outline

• Data flow overview
• Short-time scheduler
• Calibrations and observations
• Data reduction software
• Archiving
• Data reprocessing and analysis
• Some important points

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Data flow overview
OS/ICS
STS
OB
?,?,
TCS
RAW
GUIDING IMAGES
RAW
Trigger DRS
REDUCED
DAU
RAW
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Interfaces
Short-time scheduler
TCS
OS / ICS
Trigger / DRS
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The RITZ control room
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The short-time scheduler (STS)
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The short-time scheduler (STS)

• Real-time scheduling of observations
• Possibility to prepare the night in advance
• Easy-to-use cut-and-paste graphical interface
• Input from catalogues object name, coordinates,
  proper motion, approximate RV, spectral type,
  observing mode, desired SNR
• Real-time computation of observing conditions
  (position on the sky, airmass, moon, )
• Exposure time computation using built-in ETC

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Calibrations and observations

•  Standard calibration  sequence to be executed
  at the beginning of each night
• Bias measurement
• Order localization
• Flat-fielding
• Wavelength calibration
• Observations can be made in 3 different modes
• Object simultaneous reference
• Object sky
• Object only
• -gt Preparation of calibration and observation plan

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The online pipeline (trigger DRS)
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The offline trigger DRS
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Data reduction software

• Major reduction steps for science raw frames
• Bias and dark subtraction
• Order extraction with cosmic rejection
• Flat-fielding
• Wavelength calibration
• Barycentric correction
• Merging and rebinning of the orders
• Cross-correlation with stellar template
• Radial velocity and CCF bisector computation
• Instrumental drift correction (if applicable)
• Creation of reduced data products (FITS format)

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Data reduction software
Calibration recipes bias dark, order
definition, flat-fielding, wavelength calibration
RAW CALIBRATION FRAME
REDUCED CALIBRATION FRAMES
Instrument DRS configuration files
Log files
Calibration database
RAW SCIENCE FRAME
REDUCED SCIENCE FRAMES
Science recipes objectsim. reference,
objectsky, object only
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Data reduction software

• Still to be done
• Adapt DRS to HARPS-N (spectral format, keywords,
  etc.)
• Adapt wavelength calibration to laser comb /
  Fabry-Perot
• Correct background / straylight pollution
• Optimize reduction of low-SNR data
• Improve instrumental drift computation
• Update barycentric correction process
• Optimize cross-correlation process
• Develop/extend stellar diagnostics (Ca II HK
  index, bisectors, study of individual line
  shapes/shifts, )

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Data archiving unit (DAU)
transportable media

• Raw frames
• Reduced frames
• Log files
• Guiding images

Data archive Cambridge / Geneva
FTP ?
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DRS updates and data reprocessing/analysis

• DRS continuously improved and updated
• Coherence of the data is essential!
• Periodic global reprocessing of the whole archive
  to always have the best-quality data
• Extraction of the relevant information from all
  FITS headers and creation of a global database
• Use of external tools to search for planetary
  signals (period search, orbit fitting, genetic
  algorithms, significance tests, etc.)

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Some important points

• For the project
• Precisely define all interfaces (STS ICS, FITS
  headers, etc.) and if possible keep close to
  HARPS-S choices
• Use PM counting to determine the photocenter of
  the exposure
• Need for perfect guiding and record integrated
  guiding image
• While observing
• Always keep an eye on the guiding!
• Carefully check ALL target-related parameters
  (coordinates, spectral type, ) in the input
  catalogues to avoid any spurious RV effects