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megacam and COSMOS

megacam and COSMOS. H.J. McCracken for the TERAPIX team at the Institut d’Astrophysique de Paris. TERAPIX and the COSMOS u*/i* data. TERAPIX (created in 1998) is dedicated to the processing of wide field survey data Three astronomers, five engineers, one pdra; 50% ‘secure’ positions

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megacam and COSMOS

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  1. megacam and COSMOS H.J. McCracken for the TERAPIX team at the Institut d’Astrophysique de Paris

  2. TERAPIX and the COSMOS u*/i* data • TERAPIX (created in 1998) is dedicated to the processing of wide field survey data • Three astronomers, five engineers, one pdra; 50% ‘secure’ positions • Around 40Tb of raid6 150 Gflops (peak) • Very rigorous control of data processing with “real science” being done with the data at every step • Fully automated web-based pipeline • cosmos: the i* astrometric solution is derived from the USNO-B1 and this field defines the overall COSMOS astrometric reference Data bias-subtracted and flat-fielded at CFHT stacking Astrometric and photometric solution generated Input quality assessment tool run at TERAPIX and weight-maps generated output quality assessment tool is run COSMOS/NYC 13-15 Sept. 2004

  3. u* data COSMOS/NYC 13-15 Sept. 2004

  4. COSMOS-d2 i* (Megacam)

  5. scamp/swarp (E. Bertin) • The “industrial revolution” in wide-field mosaic data processing • Able to compute a full astrometric and photometric solution for many images, filters and instruments simultaneously • Extremely fast: for the cosmos i* ~100 megacam images processed in under two hours; • Simple to use (scamp *ldac; swarp *fits) • swarp already public; scamp will be released to the community at the end of September, once debugging at TERAPIX is completed COSMOS/NYC 13-15 Sept. 2004

  6. COSMOS/NYC 13-15 Sept. 2004

  7. COSMOS/MEGACAM counts in cells COSMOS/NYC 13-15 Sept. 2004

  8. S3 for lyman-break galaxies? Min/max errors (jacknife) Would expect faint field galaxies (which are weakly clustered) to have different skewness than Lyman break galaxies (which have a clustering amplitude ten times higher)….. CFDF SSRS2 (Benoist et al 1999) Not different… The cosmos field could have enough z~3 galaxies to measure accurately s3 COSMOS/NYC 13-15 Sept. 2004

  9. Next steps • We need to construct a full photometric mask for all cosmos optical data • What are the largest scales out to which clustering measurements can be made in the subaru data? • Is the subaru/cfht photometric solution stable on large scales? • Do we need more optical data “between the gaps” to produce a better overall photometric solution? • We need more u* data if we want to find Lyman-break galaxies! • High-resolution large volume simulations are needed to interpret/understand the counts in cells measurements (this is now the limiting factor) COSMOS/NYC 13-15 Sept. 2004

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