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SNIa Calibration from May 2012 Chicago Calibration meeting

SNIa Calibration from May 2012 Chicago Calibration meeting. Current State of SN Systematics Photometric Calibration U ncertainties D ominate !. From Sullivan et al. 2011.

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SNIa Calibration from May 2012 Chicago Calibration meeting

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  1. SNIa Calibrationfrom May 2012 Chicago Calibration meeting

  2. Current State of SN SystematicsPhotometricCalibration Uncertainties Dominate! From Sullivan et al. 2011

  3. Our ability to determine cosmological parameters with DL(z) is completely degenerate with our ability to perform precise photometric calibration.This is currently the main systematic limitation to SN cosmology.

  4. Current State of SN Cosmology SNLS

  5. Current State of SN Cosmology SNLS

  6. Current State of SN Cosmology SNLS

  7. Next Steps on Dark Energy: Bigger and Better Imaging Surveys

  8. Extinction above the atmosphere Broadband photometry: “Metrology and Meteorology” Source Atmosphere Instrumental transmission Four aspects to the photometry calibration challenge: Relative instrumental throughput calibration Absolute instrumental calibration (Best controlled) Determination of atmospheric transmission Determination of line of sight extinction Historical approach has been to use spectrophotometric sources (known S()) to deduce the instrumental and atmospheric transmission, but this (on its own) has become problematic if we need % precision: - integral constraints are inadequate, - we don’t know the source spectra to the required precision.

  9. Atmospheric Transmission Burke et al, ApJ 720, 811B (2010)

  10. Potential Color calibration approaches Terrestrial black-body sources, using triple point of metals, and Vega as the transfer standard 2 . Theoretical models of stellar spectra DA white dwarf stars, with 20,000K < T <80,000K. Theoretical models depend only on log (g) and T Model of Vega plays a role as well But beware of extinction effects 3. Statistical assemblage of stars, en masse. Color-color diagrams, ubercalibration tie to another photometric system. 4. Shift the calibration approach entirely, and base it on well-characterized detectors. Not mutually exclusive

  11. How to address this ? Explicit measurement of atmospheric transmission. Explicit measurement of instrumental response function. use a tunable laser in conjunction with NIST photodiode standard Explicit determination of atmospheric transmission multi-narrowband imager dispersed imager balloon-borne sources (2012) Re-assess Galactic extinction. Schlafly & Finkbeiner (2011) used SDSS to revise SFD dust map, correction factor of 0.78 at 1 micron! Try to shift away from celestial calibrators entirely.

  12. NIST Cal Photodiode Spectral Responsivity Standard Detectors − not standard sources − are the calibrator of choice - increased precision in the photodetector calibration, - ease of use, - repeatability of standard detectors relative to standard laboratory sources NIST photodiode responsivity measurements - InGaAs spectral responsivity uncertainty of 0.1% (1s) for 1.0<l<1.7 mm Photodiode detectors extremely stable over time - Si stability exceeds 15 years, thus far - InGaAs stability exceeds 10 years, thus far Eppeldauer, Metrologia 2009 updated InGaAs figure: courtesy Keith Lykke (NIST)

  13. Precise Filter Determination

  14. Collimated Source Measurements

  15. Atmospheric Transmission Burke et al, ApJ 720, 811B (2010)

  16. The Variable Aspects of Atmosphere Ozone satellite data Water Vapor EW of water lines dual-band GPS differential narrowband Aerosols stellar monitor balloon-borne lasers Clouds local zeropoint adj.

  17. Objective grating atmospheric monitor

  18. PanSTARRS-1 throughput Tonry et al arXiv:1203.0297

  19. Instri Instri Instri Instri Instrumental Sensitivity Atmospheric Transmission Spectrophotometric Standards Precise photometry Closing the loop With this initial effort, come within 5% rms of matching ab initio calculations with observations (eg, Tonryet al, arXiv:1203.0297, 2012)

  20. Summary (Chris Stubbs- May 2012) SN cosmology is stalled until we improve calibration Determination of luminosity distance vs. z is completely degenerate with our ability to calibrate photons(l). We need to determine 3 things: instrumental sensitivity function atmospheric transmission extinction along the line of sight A relative determination suffices. Don’t need absolute flux scale (zeropoint), since this is degenerate with M SN. I am dubious about any celestial spectrophotometric standard below the 1% level. We are making (slow) progress towards implementing a relative calibration based on laboratory standards.

  21. Go to Space? • HST, Gaia, Euclid • -Open issues still for absolute colour calibration • K corrections (precise inter and filter calibration) • SN model • Standard stars and detectors

  22. The future (>2020): multiprobe DE projects(LSST, KDUST,…)

  23. Absolute Color Calibration:The 5 Step Plan 1. Establish a standard candle - transfer NIST calibration standard to the source input to telescope 2. Transfer NIST calibrated standard to the ACCESS payload - calibrate ACCESS payload with NIST certified laboratory irradiance standards 3. Transfer NIST calibrated standard to the Stars - Observe Standard Stars with the calibrated ACCESS payload 4. Monitor ACCESS sensitivity - NIST calibrated on-board lamp tracks sensitivity throughout the program 5.Fit Stellar Atmosphere Modelsto the flux calibrated observations - confirm performance; refine and extend Standard Star models

  24. Euclid SN survey ? • Basic goal: a significant gain over existing SN surveys • In particular SNLS and DES • Euclid has the potential to provide the first NIR survey for SNe from space • Provides an independent Euclid probe of cosmology • With 6 months of observing time, the most interesting option is the “AAA survey” • Reaches high redshift : up to z ~ 1.5 • Cannot be done from the ground

  25. “AAA” survey[Simulations by P. Astier, K. Maguire, S.Spiro] • A dedicated Euclid SN survey • 6 months total Euclid time • split into two 6-month seasons (observing ~half time) to provide reference images • 10 sqdeg • 4 day cadence • Increased imaging exposure times: y,J,H=1200, 2100, 2100s (no spectra) • Simultaneous ground-based i and z-band • Provides 1700 well measured SNeIawith 0.75 < z< 1.5 • Complemented with low- and mid-z ground based surveys (not simultaneous) Above: example Euclid lightcurve at z=1.5 and predicted DETF FoM

  26. OPTICAL SN samples LSST in 1 year DES Union2 (current)

  27. OPTICAL and NIR SN samples Euclid* (schedule permitting) JWST E-ELT CSP (current)

  28. ACCESS

  29. ACCESSAbsolute Color Calibration Experiment for Standard Stars Status, Calibration Strategy, and Design Performance M.E. Kaiser & the ACCESS Team Calibration and Standardization of Large Surveys and Missions in Astronomy and Astrophysics 16 April 2012 This work supported by NASA grant NNX08AI65G

  30. Current Standard Star Uncertainties Uncertainty floor (circa 2007) in the fundamental stellar standards is 2%. across the 0.35 - 1.7 m bandpass(Bohlin 2007, Cohen 2007) Major uncertainty contributors: - Earth’s atmosphere Sol’n:dedicated monitoring or observe above the atmosphere - Stellar models: describe & extend the data Sol’n: Improved stellar models - need data constraints & test wrt NIST at the 1% level Judicious selection of standard stars - Observe existing (known) standard stars - Vega(A0V) - absolute VIS NIR std, bright (V=0.026), pole-on-rotator => variety of thermal zones, complex - Sirius(A1V) - IR std, bright (V=-1.47) - BD +17o4708(sdF8) simpler spectra, SDSS std, fainter +,- - HD 37725 (A3V) - absolute calibrator for IR satellites, possible alternate target: HD84937 (F5V) - Minimize spectral features & enable robust modeling - Flux level chosen to minimize calibration transfers A single stellar calibrator spanning the full bandpass introduces less error than when two stellar calibrators are required to span the bandpass.(Lampton 2002, Kim et al., 2004 )

  31. Observe above the Earth’s Atmosphere Sounding Rocketobserves completely above the Earth’s atmosphere - eliminates problem of measuring residual atmospheric abs’pn seen by balloons - OH arises at 70 km; typical balloon altitude: 39 km, rocket altitude: 300 km - OH airglow emission lines are 10-100X stronger than 13th mag star - continuous spectral calibration across the 0.35 - 1.7 m bandpass Balloon: OH introduces additional complexity - increased statistical noise & systematics from bkrnd subtraction - increased instrument costs to avoid scattered OH airglow Rocket disadvantage: Flight times are short (~400 sec)  Limits faintest standard to ~ 9th magnitude (BD+17o4708) with <1% uncertainty Establish repeatability: Two flights per target - Vega & Sirius 12h apart - four flights of 2 targets each

  32. ACCESS: Optical Design Telescope:F/15.72 Dall-Kirkham Primary figure: ellipse 393 mm (15.47in) diameter Secondary figure: sphere Coatings: MgF2 over Al Spectrograph: Slit: 1mm (33 arcsec/mm) Grating: Concave, Blaze angle:1.65o Utilize multiple orders 1st : 0.9 – 1.9 mm 2nd : 0.45 – 0.95 mm 3rd : 0.30 – 0.63 mm Cross disperser: Prism spherical figure

  33. ACCESS Payload - Spectrograph The End

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