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OmegaCAM: The 16k x 16k Survey Camera for the VST

OmegaCAM: The 16k x 16k Survey Camera for the VST. Calibration, Data Analysis Strategy and Software. Erik R. Deul Konrad Kuijken Edwin A. Valentijn. People involved. The Netherlands Kapteyn Institute : J-W. Pel, K. Begeman, D.R. Boxhoorn, E. Valentijn, K. Kuijken

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OmegaCAM: The 16k x 16k Survey Camera for the VST

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  1. OmegaCAM: The 16k x 16k Survey Camera for the VST Calibration, Data Analysis Strategy and Software Erik R. Deul Konrad Kuijken Edwin A. Valentijn

  2. People involved • The Netherlands Kapteyn Institute: J-W. Pel, K. Begeman, D.R. Boxhoorn, E. Valentijn, K. Kuijken Sterrewacht Leiden: R. Rengelink, E.R. Deul • Germany Universitäts-Sternwarte München: R. Bender, L. Greggio, R. Häfner, U. Hopp, H. Kravkar, W. Mitsch, B. Muschielok, M. Neeser, R. Saglia Universitäts-Sternwarte Göttingen: R. Harke, H. Nicklas, W. Wellem Sternwarte der Universität Bonn: K. Reif • Italy Astronomical Observatory of Capodimonte - Napoli: E. Cascone Osservatorio Astronomico di Padova: A. Baruffolo, E. Cappellaro, E. V. Held, H. Nazaryan, G. Piotto, H. Navarsadyan, L. Rizzi • ESO D. Baade, A. Balestra, J-L. Beckers, C. Cavadore, C. Cumani, F. Christen, S. D'Odorico, S. Deiries, N. Devillard, C. Geimer, N. Haddad, G. Hess, J. Hess, O. Iwert, H. Kotzlowski, J-L Lizon, A. Longinotti, W. Nees, A. Renzini, J. Reyes Moreno, G. Sikkema, M. Tarenghi SPIE Conference [4836] Survey and Other Telescopes Technologies and Discoveries

  3. Detectors • Science array 1 x 1 degree, 32 CCDs • 15 mm pixels – 0.21 arcsec/pixel • Marconi (former EEV) 2k x 4k • 16k x 16k pixels • Auxiliary CCD’s – 4 CCDs • For guiding • Image analysis SPIE Conference [4836] Survey and Other Telescopes Technologies and Discoveries

  4. Filters More details see Harald Nicklas [4836-34] • Primary set • Sloan u’, g’, r’, i’, z’ • Johnson B, V • Narrow-band e.g. Ha up to 8000 km/s • Composite u’,B,V,i’ in four quadrants • User filter SPIE Conference [4836] Survey and Other Telescopes Technologies and Discoveries

  5. VST construction see [4836-09] Mancini Details instrument control see [4848-10] Baruffolo

  6. Wide Field Imaging Science • Provide targets for VLT • 2/3 of time through ESO’s OPC • Individual programs • Supernovae, Lensing, Kuiper belt objects, Gamma ray, bursts, Microlensing, Brown dwarfs, High proper motion objects, Galactic halo objects, Quasars, AGNs • Sky Surveys • Long term archival research (10 yr mission) • Science Cases • Finding exceptional single, rare objects • Statistics on large samples of objects SPIE Conference [4836] Survey and Other Telescopes Technologies and Discoveries

  7. Large Data Volume • Handling of the data is non-trivial • Pipeline data reduction • Calibration and re-calibration • Image comparisons and combinations • Working with source lists • Visualization } ESO compliant • Wide-field imaging instruments, vast amounts of data • E.g.: VST = Southern sky (30 min exp, 300 nights/y) in 3 years. Large amount of data! 100 Tbyte • Science can only be archive-based SPIE Conference [4836] Survey and Other Telescopes Technologies and Discoveries

  8. Concepts for solution • Environment that provides systematic and controlled • Access to all raw and calibration data • Execution and modification reduction/calibration pipelines • Execution of source extraction algorithms • Archiving reduced data and source lists, or regenerates these dynamically • Can be federated to link different data centers • Dynamical archive continuously grows, can be used for • small or large science projects • generating and checking calibration data • exchanging methods, scripts and configuration • Key functionality • Link back from source data to the original raw pixel data and calibration files SPIE Conference [4836] Survey and Other Telescopes Technologies and Discoveries

  9. How to use this • Deep multi-color fields • No need to take all data in one campaign • Combine data of particular quality, assess results • Select sources, visualize interesting ones, … • 1-in-1,000,000 events spurious or not? • Large homogeneous surveys • E.g. weak lensing maps, cluster searches, star counts • Variability (source list- or pixel based) • Proper motions (asteroids, nearby stars) • Flux variations • Monitor instrument (calibration files) • Planning observations • View quality of existing data • Build on what already exists, add more filters, more exposure time, better seeing, … SPIE Conference [4836] Survey and Other Telescopes Technologies and Discoveries

  10. Solution • Procedurizing • Data taking at telescope for both science and calibration data • Full integration with data reduction • Design • Data model (classes) defined for data reduction and calibration • View pipeline as an administrative problem SPIE Conference [4836] Survey and Other Telescopes Technologies and Discoveries

  11. Observing Modes • Dithermatching max. gap between arrays ~400 pixels • N pointings (N=5 is standard) • nearly cover all gaps in focal plane and maximizes sky coverage • the context map will be very complex • couple the photometry among individual CCDs. • Jittermatching the smallest gaps in CCDs ~5 pixels • optimizes for maximumhomogeneity of the context map • observationsfor which the wide CCD gaps are not critical • all data from single sky pixel originates from single chip • Stare reobserving fixed pointing positions multiple times • main workhorse monitoring instrumentand optical transients. • SSO observing Solar System objects • non-siderial tracking and the auto guiding switched off. SPIE Conference [4836] Survey and Other Telescopes Technologies and Discoveries

  12. Observing Strategies • Standard • Single observations (one observing block) • Deep • Long, multiple integrations • Selected atmospheric conditions • Several nights • Frequent • Monitors same field • Timescales from minutes to months (overriding) • Mosaïc • Maps areas of sky > 1o SPIE Conference [4836] Survey and Other Telescopes Technologies and Discoveries

  13. Calibration procedures Sanity checks Image pipeline Source pipeline Calibration procedures Quality control SPIE Conference [4836] Survey and Other Telescopes Technologies and Discoveries

  14. Science Observations Bias pipeline Source pipeline Flatfield pipeline Photometric pipeline Image pipeline SPIE Conference [4836] Survey and Other Telescopes Technologies and Discoveries

  15. Monitoring Photometric Calibration SPIE Conference [4836] Survey and Other Telescopes Technologies and Discoveries

  16. Share the load • Processing • Hardware • Beowulf processors – 32 (most cases) • Multi Terabyte disks (10 – 100) • Data reduction • Derive calibration • Run image pipeline (1 Mpx/s) • Archiving • Storage • Images (100’s Tbyte), Calibration files (10 Tbyte) • Source parameters (1-10 Tbyte) • Federate (network speed) • 5 Mb/s (24 hours/day) full replication • 200 Mb/s no replication, on-the-fly retrieval SPIE Conference [4836] Survey and Other Telescopes Technologies and Discoveries

  17. Contents of federation • Raw data • Observed images • Ancillary information • Calibration results • Calibration files time stamped • Reduced images • Single observation • Coadded images • Software • Methods (pipelines) for processing calibration • Configuration files • Source lists – catalogues • Extracted source information • Associated among different data objects SPIE Conference [4836] Survey and Other Telescopes Technologies and Discoveries

  18. Concepts of federation • Federation maintained by a single database • Full history tracking • of all input that went into result • providing on-the fly reprocessing • Dynamical archive - Context as object attributes • Project: Calibration, Science, Survey, Personal • Owner: Pipeline, Developer, User • Strategy: Standard, Deep, Freq (monitoring), Mosaïc • Mode: Stare, Jitter, Dither, SSO • Time: Time stamping • Software standards • Classes/data model/procedures • 00 – inheritance/ persistency • Python scripts/ c-libraries SPIE Conference [4836] Survey and Other Telescopes Technologies and Discoveries

  19. Schedule • Hardware • Dome/Telescope erected at location • Camera on telescope Q1 2004 • First run: Jan 2004 • Second run: Mar 2004 • Software • Design – review Q2 2002- Done • Basic operations – Q4 2003 • Evaluate and prepare for mass production 2004 • Qualify and populate 2005 • Deliver survey system – satellites SPIE Conference [4836] Survey and Other Telescopes Technologies and Discoveries

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