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The Astro-Wise standard stars (with a focus on OmegaCAM)

The Astro-Wise standard stars (with a focus on OmegaCAM). Gijs Verdoes Kleijn & Ronald Vermeij For the Astro-Wise consortium. Aim: sampling complete FOV with photometric calibrators. OmegaCAM FOV. OmegaCAM FOV. Aim: sampling complete FOV with photometric calibrators. OmegaCAM FOV.

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The Astro-Wise standard stars (with a focus on OmegaCAM)

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  1. The Astro-Wise standard stars (with a focus on OmegaCAM) Gijs Verdoes Kleijn & Ronald Vermeij For the Astro-Wise consortium

  2. Aim:sampling complete FOV with photometric calibrators OmegaCAM FOV

  3. OmegaCAM FOV Aim:sampling complete FOV with photometric calibrators

  4. OmegaCAM FOV Aim:sampling complete FOV with photometric calibrators • Accurate photometric calibration ( per chip) • Quantifying sky concentration effects

  5. Photometric accuracies • Instrumental requirement: 5% accuracy in photometry with usual data reduction • Our estimate: with Astro-Wise infrastructure 2-3% achievable with bit extra work on top usual data reduction

  6. OmegaCAM calibration plan

  7. All-year round monitoring field near South Equatorial Pole Purpose: monitor instrument performance and atmospheric conditions through night Candidate field: (ra,dec)=(51.429,89.04)deg (l,b)=(302.29 -27.82)deg

  8. Standard star catalog in Astro-Wise • 8 equatorial fields • Final catalog will be produced from OmegaCAM observations of fields in first year. • Currently a preliminary version in place • to be used during commissioning. • derived from WFC/INT La Palma data • WFC data was calibrated using Landolt standards (transformed to Sloan system)

  9. The standard star fields

  10. The content of a field Field SA92 ● = Landolt stars published data (transformed to ugriz) + = Sloan published data ●= “AW2S”,our secondary standards obtained from WFC/INT La Palma data

  11. Deriving a Zeropoint • Reduce standard starfield • Associate stars with entries in • standard star catalog. • Sigma clip to discard outliers • Estimate zeropoint for each remaining star • Zeropoint= weighted mean of estimates

  12. Work in progress • Good determination random and systematic errors of standard star • magnitude in the catalog • measured flux • Propagation of these errors to ZPT

  13. Aw2S-SDSS3 magnitude residuals SA92 SA101 SA104 SA107 SA113

  14. SA92

  15. SA101

  16. SA104

  17. SA107

  18. SA113

  19. Independent photometry checks • Galaxy number counts

  20. Stellar locus in color-color space Izevic et al 2004

  21. In conclusion • First version of standard star catalog in Astro-Wise in place: accuracy/systematics analysis in progress. • Additional independent photometry checks being considered.

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