The secondary standards for OmegaCAM2

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 : 

Aim: sampling complete FOV with photometric calibrators OmegaCAM FOV

Aim: sampling complete FOV with photometric calibrators : 

Aim: sampling complete FOV with photometric calibrators

Aim: sampling complete FOV with photometric calibrators : 

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

Photometric accuracies: 

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

OmegaCAM calibration plan: 

OmegaCAM calibration plan

All-year round monitoring field near South Equatorial Pole: 

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

Standard star catalog in Astro-Wise: 

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)

The standard star fields: 

The standard star fields

The content of a field: 

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

Deriving a Zeropoint: 

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

Work in progress: 

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

Slide13: 

SA92 SA101 SA104 SA107 SA113 Aw2S-SDSS3 magnitude residuals

SA92: 

SA92

SA101: 

SA101

SA104: 

SA104

SA107: 

SA107

SA113: 

SA113

Independent photometry checks: 

Independent photometry checks Galaxy number counts

Stellar locus in color-color space : 

Stellar locus in color-color space Izevic et al 2004

In conclusion: 

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