1 / 18

The OmegaCAM photometric systems

The OmegaCAM photometric systems. OmegaCAM calibration plan (1). Basic OmegaCAM terminology :. Key bands vs User bands Key band -> User band transformation tables Monolithic filters and calibration filter Polar field and equatorial fields Monitoring.

lilal
Download Presentation

The OmegaCAM photometric systems

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. The OmegaCAM photometric systems

  2. OmegaCAM calibration plan (1) BasicOmegaCAM terminology : • Key bands vs User bands • Key band -> User band transformation tables • Monolithic filters and calibration filter • Polar field and equatorial fields • Monitoring

  3. OmegaCAM calibration plan (2)

  4. OmegaCAM calibration plan (3) Important considerations : • OmegaCAM iscontinuously maintained in the Key bands( u', g', r', i' ) • standard fields onlyobserved in User bands if the science programme of the night warrants it • photometric calibration is done per-chip

  5. OmegaCAM photometric standard stars Standard fields used for daily calibration : • field centered on south celestial pole (polar field) • eight equatorial fields : SA 92, SA 95, SA 98, SA 101, SA104, SA 107, SA 110, SA113 Available photometric bands : u', g', r', i'

  6. OmegaCAM photometric standard stars : preparatory programs Establishing photometric standards : • INT Secondary Standards Preparatory Programme • OmegaCAM Secondary Standards Programme Photometric standards presently available : • classisal Landolt catalog • stars from Sloan Digital Sky Survey • new : candidate Sloan standards for SA 98

  7. OmegaCAM photometric standard stars : INT/La Palma preparatory program (1) Establishing photometric standards for SA 98 : • data was processed with the Astro-Wise system • photometric transformation coefficients determined using Sloan standards • no illumination correction was required for INT Results : ~ 23.000 candidate secondary standards covering a FoV of 1.1deg X 1.1deg

  8. OmegaCAM photometric standard stars : INT/La Palma preparatory program (2) Monitoringthe quality of the night Standard extinction coefficients adopted : u' = 0.47 r' = 0.09 g' = 0.19 i' = 0.05

  9. OmegaCAM photometric standard stars : INT/La Palma preparatory program (3) Color terms : u' : none detected g' : 0.14 +/- 0.01 r' : none detected i' : 0.07 +/- 0.01

  10. OmegaCAM photometric standard stars : INT/La Palma preparatory program (3) Zeropoints : u' : 23.725 +/- 0.019 (1) 23.772 +/- 0.019 (2) 23.575 +/- 0.039 (3) 23.542 +/- 0.029 (4) 24.939 +/- 0.016 (1) 25.064 +/- 0.005 (2) 25.091 +/- 0.008 (3) 25.122 +/- 0.004 (4) 24.579 +/- 0.015 (1) 24.702 +/- 0.010 (2) 24.806 +/- 0.009 (3) 24.803 +/- 0.010 (4) 24.126 +/- 0.018 (1) 24.255 +/- 0.012 (2) 24.412 +/- 0.011 (3) 24.413 +/- 0.007 (4) g' : r' : i' :

  11. OmegaCAM photometric standard stars : INT/La Palma preparatory program (5) Comparing the photometric solution with an independent field

  12. OmegaCAM photometric pipeline (1) :top-level recipes Top-level recipes of the photometric pipeline : • PhotCalExtractResulttable --> deriving catalogs • PhotCalExtractZeropoint --> deriving zeropoints • PhotCalMonitoring --> monitoring • IlluminationCorrectionVerify • IlluminationCorrection

  13. OmegaCAM photometric pipeline (2) :photometric catalog Photometric pipeline works with catalogs Making these catalogs is always the first processing step in the photometric pipeline photcat = PhotSrcCatalog() photcat.astrom_params = astrom photcat.frame = frame photcat.refcat = refcat photcat.make() photcat.inspect()

  14. OmegaCAM photometric pipeline (3) :extinction + zeropoint Last processing step in photometric pipeline Extinction derived earlier in one of many ways End result used in image pipeline photom = PhotometricParameters() photom.extinct = extinct photom.photcat = photcat photom.make() photom.inspect()

  15. OmegaCAM photometric pipeline (4) :illumination correction Verification of the presence of sky concentration effects Plot shows the variation of the zeropoint as a function of its position on the detector block plot = create_plot('IllumVerify') plot.show(photcats) Verification of a WFI image observed in filter #844

  16. OmegaCAM photometric pipeline (5) :illumination correction Characterising the sky concentration effect illum = IlluminationCorrection() illum.photcats = photcats illum.make() illum.inspect()

  17. OmegaCAM photometric pipeline (6) :illumination correction Peak to peak variation : 0.94 – 1.03 f = IlluminationCorrectionFrame() f.illum = illum f.chip = chip f.make() image = Image('MEF.fits') image.frames = frames image.make() The eight illumination correction frames for WFI filter #844

  18. OmegaCAM photometric systems : resources • “OmegaCAM Data Flow System – users and programmers manual V2.11” • “OmegaCAM Secondary Standards preparatory programme – progress report” • http://portal.astro-wise.org/

More Related