Measuring the Cosmological Parameters with the Supernova Legacy Survey

Introduction The Supernova Legacy Survey Photometric Calibration of the SNLS Fields Conclusion

LPNHE - IN2P3 - CNRS - University Paris 6 and Paris 7

Observatoire de Besan¸con – 09/11/2006

Nicolas Regnault [email protected] Measuring the Cosmological Parameters with theSupernova Legacy Survey Introduction The Supernova Legacy Survey Photometric Calibration of the SNLS Fields Conclusion Outline

1 Introduction Type Ia Supernovae Measuring the Cosmological Parameters Measuring the Dark Energy Equation of State

2 The Supernova Legacy Survey Analysis of the First Year Dataset Systematics Ongoing Work

3 Photometric Calibration of the SNLS Fields Motivations Analysis of the Photometric Grid The E98/E95 Program

4 Conclusion

Nicolas Regnault [email protected] Measuring the Cosmological Parameters with theSupernova Legacy Survey Introduction Type Ia Supernovae The Supernova Legacy Survey Measuring the Cosmological Parameters Photometric Calibration of the SNLS Fields Measuring the Dark Energy Equation of State Conclusion Outline

1 Introduction Type Ia Supernovae Measuring the Cosmological Parameters Measuring the Dark Energy Equation of State

2 The Supernova Legacy Survey Analysis of the First Year Dataset Systematics Ongoing Work

3 Photometric Calibration of the SNLS Fields Motivations Analysis of the Photometric Grid The E98/E95 Program

4 Conclusion

SNe Ia very luminous can be identiﬁed (spectra)

ﬂuctuations of Lmax ∼ 40% can be reduced to ∼ 14%

(ΩΜ,ΩΛ) = ( 0, 1 ) (0.5,0.5) (0, 0) ( 1, 0 ) (1, 0) 24 (1.5,−0.5) (2, 0) Flat 22 Λ = 0 Supernova Cosmology B 20 Project m

18 effective

Calan/Tololo 16 (Hamuy et al, A.J. 1996)

(ΩΜ,ΩΛ) = ( 0, 1 ) SNLS-04D3fk (0.5,0.5) (0, 0) ( 1, 0 ) (1, 0) 24 (1.5,−0.5) (2, 0) gM iM Flat r Λ = 0 M 22 z M Supernova Cosmology B Project Flux 20 m

18 effective

Calan/Tololo 16 (Hamuy et al, 0 A.J. 1996) 3100 3150 3200 JD 2450000+ 14

Measure SN apparent luminosity @ peak, in a given spectral region ⇒ (k-corrections). Use additional observables, to improve distance indicators decline rate / lightcurve width ⇒ good sampling of LC color ⇒ observations in several passbands

2 Z z 0 H(z) 3 1 + w(z ) 0 2 = Ωm(1 + z) + ΩX exp 0 dz + Ωk (1 + z) H0 0 1 + z

Exact or quasi-degeneracies The expansion history depends on the sum of 3 terms the equation of state enters in only one of them

⇒ need to know Ωk (from CMB)

⇒ if w(z) arbitrary, relation between Ωm and w(z) ⇒ even assuming a constant w, there remain a strong degeneracy

Type Ia Supernovae Measures Optical and IR telescopes r(z) Figure of merit: # SNe, z span

Measures Combination of Weak Gravitational Shear r(z) Optical telescopes r(zlens , zsource ) Figure of merit: surveyed area on the sky (up to z ∼ 1) P(k, z)

Baryon Accoustic Oscillations Measures Combination of

Optical telescopes, imaging and spectroscopy r(z), H(z) 2 Figure of merit: surveyed Universe volume Ωmh

The Pioneers

Supernova Cosmology Project Riess et al, 1998 [10 SNe Ia] 3 Knop et al. (2003) Perlmutter et al, 1999 [42 SNe Ia] No Big Bang Spergel et al. (2003) Allen et al. (2002) 2 The HST Era Supernovae Sullivan, 2002 [Host Galaxy Types] 1 Ω Tonry, 2003 [+10 high-z SNe] Λ CMB Barris, 2003 [+23 SNe Ia @ z < 1] expands forever 0 entually Knop et al 2003 [+11 SNe Ia, followed-up HST] recollapses ev Clusters closed Riess et al 2004 [+16 SNe Ia, discovered HST (z → 1.6)] flat -1 open

The New Generation Surveys 0 1 2 3 Ω SNLS Coll, 2005 [71 new SNe Ia, 0.3 < z < 0.9, 500 by M the end of the SNLS]

+0.15 w = −1.05−0.20(stat) ± 0.09(sys)

1.0

0.5

0.0 (m−M) (mag) ∆ −0.5 Ground Discovered −1.0 HST Discovered Ω =1.0) Ω =1.0) M M Evolution ~ z, (+ 0.5 high−z gray dust (+

0.0 (m−M) (mag) ∆ Ω −0.5 M=1.0, Ω Empty (Ω=0) Λ=0.0 Ω Ω M=0.27, Λ=0.73 "replenishing" gray Dust 0.0 0.5 1.0 1.5 2.0 z

in the past, dark matter was dominating, Universe was decelerating excludes the grey dust hypothesis

0.0 Ω =0.27+/−0.04 M 2dFGRS 8 Gold w/o HST−discovered Gold 6 95% WMAPext −0.5 SNe Ia 4

68% 95%99% 99% w‘ 2 90% 68% 95% 95% 68% 68% 0 95%90%

w −1.0 Ω Ω −2 M=0.27+/−0.04 M=0.27+/−0.04 8 Gold+Silver Gold+Systematic: +/−0.05*z 6 99% 4 −1.5 95%

w‘ 2 68% 99% 90% 0 95%

−2.0 Ω Ω −2 M=0.27+/−0.04 M=0.27+/−0.04 0.0 0.2 0.4 0.6 0.8 0.0 0.2 0.4 0.6 0.8 Ω Ω M M −3 −2 −1 0 −3 −2 −1 0 w0 w0 +0.13 w = −1.02−0.19 and w < −0.76(95%CL)

Consistent with w0 = −1 and dw/dz = 0 (Λ)

Nearby Factory: z ∼ 0.05 500 deg2 / day Integral Field Spectrometer 5 years, from 2003.

SDSS-II: z ∼ 0.2 300 deg2 ugriz-bands 3 years from 2005

SNLS @ CFHT: 0.2 < z < 1 4 deg2 ugriz-bands

ESSENCE @ CTIO: 0.2 < z < 0.8 8 deg2 RI -bands.

HST/ACS z > 1 PANS (Riess et al) Cluster Search (Perlmutter et al)

Ground Based Projects Pan-Starrs (@HAWAII): 4 1.5-m telescopes, FOV=3 deg2 Dark Energy Camera (@CTIO) FOV=3 deg2, griz Large Synoptic Survey Telescope: one 8-m telescope, FOV=9 deg2 (250000 SNe/year)

SNe Ia from Space SNAP: 2-m telescope, 1 deg2 FOV, 0.35µm − 1.7µm spectrograph DUNE: 1.5-m telescope, 0.5 deg2 FOV, 5 ﬁlters. No spectrograph

Ω Ω Comparaison de DUNE avec SNAP et CFHTLS , M libre Comparaison de DUNE avec SNAP et CFHTLS : w(z)=w0+2w'(1-a) , M fixe

-0.5 w DUNE w' 1.5 DUNE SNAP SNAP -0.55 CFHTLS CFHTLS

1 -0.6

-0.65 0.5

-0.7

-0.75 0

-0.8

-0.5

-0.85

-0.9 -1

-0.95

-1.5 -1 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 -1.4 -1.3 -1.2 -1.1 -1 -0.9 -0.8 -0.7 -0.6 Ω M w0 SYSTEMATIQUES:DUNE=0.01(1+z),SNAP=0.02(1+z)/2.7,CFHTLS=0.02(1+z) SYSTEMATIQUES:DUNE=0.01(1+z),SNAP=0.02(1+z)/2.7,CFHTLS=0.02(1+z)

Nicolas Regnault [email protected] Measuring the Cosmological Parameters with theSupernova Legacy Survey Introduction Analysis of the First Year Dataset The Supernova Legacy Survey Systematics Photometric Calibration of the SNLS Fields Ongoing Work Conclusion Outline

1 Introduction Type Ia Supernovae Measuring the Cosmological Parameters Measuring the Dark Energy Equation of State

2 The Supernova Legacy Survey Analysis of the First Year Dataset Systematics Ongoing Work

3 Photometric Calibration of the SNLS Fields Motivations Analysis of the Photometric Grid The E98/E95 Program

4 Conclusion

O(1000) SNe Ia – 10× present statistics

detected before maximum

followed-up in 4 passbands (gM , rM , iM , zM )(∼ SDSS bands) a good sampling of the lightcurves (1 point every 3 days) spectroscopic identiﬁcation of all the SNe Ia

Justiﬁcations

Large statistics → better control of the systematics One single detector → better control of calibration & selection bias Multiband observations → to follow the same spectral region @ diﬀerent z BV @ z ∼ 0 → gr @ z ∼ 0.2 → ri @ z ∼ 0.4 → iz @ z ∼ 0.8 Multiband observations → redundant measurements of distances

∼ 300h / year on a 3.6-m

CFHT @ Hawaii

Wide Field Camera

Megacam (CEA/DAPNIA) 1 deg2, 36 2k×4k CCDs Good PSF sampling 1 pix = 0.2” Excellent image quality: 0.7” (FWHM)

Rolling search mode

Component of the CFHTLS survey 40 nights / year during 5 years Four 1-deg2 ﬁelds repeated observations (3-4 nights) in 4 bands (griz) queue observing (minimize impact of bad weather)

Goals spectral identiﬁcation of SNe Ia (z < 1) redshift determination (host galaxy lines) complementary programs detailed studies of SNe Ia

Telescopes VLT large program (80h / semester) Gemini (60h / semester) Keck (30h / semester, Spring Semester)

(Howell et al, 2005 – ApJ 634, 1190)

Follow-up of the same 4 ﬁelds

Follow-up and detection performed on the same dataset 4 1 deg2 fields (2 fields visible at a given time of the year) Observations every 2-3 nights, during new moon periods (15 − 18 days). griz bands used for the detection 5 years → 2000 detections → 700 identified supernovae

Differential photometry PSF photometry of the field stars Calibration of the DEEP fields Fit of multicolor lightcurves Luminosity Distance Estimation Cosmological Results Systematics

The Model (Simultaneous ﬁt on ∼ 300 images

I (x, y) = Flux × [Kernel ⊗ PSFbest](x − xsn, y − ysn) + [Kernel ⊗ Galaxybest](x, y) + Sky

(z = 0.28) (z = 0.95)

0.2

0.1

c 0 K

-0.1

-0.2 U B V R 4000 5000 6000 λ (Å)

Empirical model of SN Ia Spectral Energy Distribution (SED) as a function of

the date w.r.t. the date of B maximum the rest-frame wavelength dilatation of phase axis in the B-band (stretch) a color parameter (@ B-band maximum)

Trained on a sample of nearby SNe Ia in UBVR (w/o using their distances)

SNLS-04D3fk SNLS-04D3gx

gM gM iM iM rM rM

zM zM Flux Flux

0 0 3100 3150 3200 3100 3150 3200 JD 2450000+ JD 2450000+

z = 0.3578 z = 0.91

R−band I−band

1998ax 0.8 z=0.50 0.8

0.4 0.4

normalized flux 0 0

−850 −40 0 40 80 120 150 550 −250 −40 0 40 80 120 150 350 LC from (Knop et al, 2003), 2 bands, HST + Ground base telescopes

8000 4000 RMS 7000 RMS 3500 rm-R 0.0082 6000 0.0088 0.12 3000 5000 2500 4000 0.1 2000 3000 1500

2000 0.08 1000 500 1000

0 0 0.06 -0.05 0 0.05 -0.05 0 0.05 g - g mean r - rmean 0.04

RMS 2500 RMS

0.02 8000 0.0101 2000 0.0159

6000 0 1500 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 V-R 4000 1000

2000 500

0 0 align the SNLS flux scales on the nearby -0.05 0 0.05 -0.05 0 0.05 i - i z - zmean supernova flux scales mean using repeated (photometric) observations of monitor the stability of the camera Landolt stars assert the spatial uniformity of the camera (36 then, we use well measured field stars to independant CCDs) transport the calibration alignment precision on the repeatability of the measurements: Landolt catalog: ∼ 1 − 3% < 1% in gri, ∼ 1.5% in z

44 SNLS 1st Year 42

40 B

µ Distance Estimate 38 „ dLH0 « Ω Ω m (z) − M − α (s − 1) + β c = 5 log 36 ( m, Λ)=(0.26,0.74) B B 10 Ω Ω c ( m, Λ)=(1.00,0.00) 34 0.2 0.4 0.6 0.8 1 SN Redshift Objects

1 44 nearby SNe Ia (literature) )

0 71 SNLS SNe Ia H -1 0.5 c L

( d Intrinsic Dispersion

10 0 2 σint = 0.13 mag (to get χ /dof = 1) - 5 log

B -0.5 µ

-1 0.2 0.4 0.6 0.8 1 SN Redshift

-0.4 2 99,7 % 95 % Ω +Ω =1 -0.6 68 % M X 1.8 -0.8 SNLS 1st Year No Big Bang -1 SNLS 1 1.6 BAO (SDSS)

st w -1.2 Year 1.4 99,7 % -1.4

95 % -1.6 1.2 68 % -1.8 Λ

1 BAO (SDSS) Ω -2 0 0.1 0.2 0.3 0.4 0.5 0.6 Ω 0.8 M

0.6 BAO = Baryon Accoustic Peak (Eisenstein, Closed 2005) Flat Accelerating Open 0.4 Decelerating 68.3, 95.5 and 99.7 CL ﬁt parameters (stat only) 0.2 (Ωm, ΩΛ) (0.31 0.21, 0.80 0.31) (Ω Ω , Ω +Ω ) ( 0.49± 0.12, 1.11± 0.52) 0 m Λ m Λ (Ω ,−Ω ) ﬂat − Ω ±=0.263 0.±037 0 0.2 0.4 0.6 0.8 1 1.2 m Λ m (Ω , Ω ) + BAO (0.271 0.020, 0.751± 0.082) Ω m Λ ± ± M (Ω , w)+BAO (0.271 0.021, 1.023 0.087) m ± − ±

Photometric calibration & modeling of the passbands Empirical modeling of lightcurves restframe region used: (B, V )) → (U∗, B) at large z modeling of the SED in the far-UV is crucial for z > 0.8 Detection biases simulation of the detection pipeline Contamination Evolution eﬀects study of SN Ia properties as a function of Host Galaxy comparison of nearby and distant SNe Ia Extinction by intergalactic dust Gravitational lensing

× β 0.5

0.5 α ) - 0 ) + 0 H -1 H c -1 l c (d 0 l 0 10 (d 10 - 5 log

B -0.5 - 5 log µ -0.5 B µ 0.6 0.8 1 1.2 -0.2 0 0.2 0.4 stretch color Hubble diagram residuals Hubble diagram residuals (no stretch corrections applied) (no color corrections applied) as a function of stretch. as a function of color.

brighter-bluer and brighter-slower relations at z = 0 (blue points) and z ∼ 0.6 (black points) are compatible.

SN Ia evolution check Compare nearby and distant SN early lightcurve shape (B-band) nearby: 19.58 ± 0.2 distant: 19.10 ± 0.2(stat) ± 0.2(sys)

250 z > 0.589 z < 0.589 1.0 200

150 0.5 N 100 0.0 Normalized B flux

50 −0.5 0 −40 −20 0 20 40 60 17.5 18.0 18.5 19.0 19.5 20.0 20.5 Effective Day rise time (days)

High redshift Strongly SF−ing 12 N: 41 10 SNe exploding in a high SFR 8 6 environment 4 2 0 display a larger stretch (and are Weak SF−ing 12 N: 30 10 brighter) 8 6 Number 4 ⇒ younger progenitors produce 2 0 brighter SNe Ia ? Passive 12 N: 20 10 8 no impact on the distance 6 4 measurement for the 1 year sample 2 0 0.7 0.8 0.9 1.0 1.1 1.2 Stretch

SN Ia evolution check (relying on spectroscopic measurements) No systematic oﬀset Dispersion increases with z: likely to be S/N

350 SNLS Data SNLS Data SCP Data SNLS Data SCP Data 40 ESSENCE Data SCP Data 250 ESSENCE Data 300 ESSENCE Data Low−z: 1991T−like Low−z: 1991bg−like Low−z: Branch Normal Low−z: 1991bg−like Low−z: 1991T−like Low−z: 1991T−like Low−z: Branch Normal Low−z: Branch Normal 30 200 250

200 20 150 150 100 10 100 Rest Frame EW − Angstroms Rest Frame EW − Angstroms Rest Frame EW − Angstroms 50 0 50 0 −15 −10 −5 0 5 10 15 0 −15 −10 −5 0 5 10 Effective Day −15 −10 −5 0 5 10 15 20 Effective Day Epoch, restframe, relative to max. luminosity

0.4

SN Redshift i'AB

0.2

0 0 0.5 1 20 22 24 color

stretch color -0.2

-0.4 0.2 0.4 0.6 0.8 1 SN Redshift 1 0.6 0.8 1 1.2 -0.4 -0.2 0 0.2 0.4

0.5 Impacts on Ωm

As we get closer to the detection limit, we are 0 more likely to detect brigther (bluer, slower) supernovae aﬀects nearby sample and SNLS sample -0.5

δΩm(Nearby SNe): +0.019 ± 0.012 Residuals to Hubble diagram -1 δΩm(SNLS SNe):−0.020 ± 0.010 0.2 0.4 0.6 0.8 1 SN Redshift

Source σ(Ωm) σ(Ωtot ) σ(w) σ(Ωm) σ(w) (ﬂat) (with BAO) Zero-points 0.024 0.51 0.05 0.004 0.040 Vega spectrum 0.012 0.02 0.03 0.003 0.024 Filter bandpasses 0.007 0.01 0.02 0.002 0.013 Malmquist bias 0.016 0.22 0.03 0.004 0.025 Sum (sys) 0.032 0.55 0.07 0.007 0.054 Sum (stat) 0.042 0.53 0.10 0.021 0.090

Flat ΛCDM Cosmology

Ωm = 0.263 ± 0.042(stat) ± 0.032(sys)

Flat (Ωm, w) Cosmology (combined w/ BAO)

Ωm = 0.271 ± 0.021(stat) ± 0.007(sys) w = −1.023 ± 0.090(stat) ± 0.054(sys)

conﬁrms acceleration of the expansion results fully compatible with Λ systematics can still be improved

Nearby SNe 44 ∞ 44 132 132 250 Distant SNe 71 71 213 213 500 500 w/ current σ(Ωm) 0.023 0.019 0.019 0.019 0.018 0.018 BAO accuracy σ(w0) 0.088 0.073 0.076 0.064 0.060 0.055 BAO ×2 σ(Ωm) 0.016 0.014 0.014 0.013 0.013 0.013 2 (8000 deg ) σ(w0) 0.081 0.062 0.067 0.054 0.049 0.044

Improve photometric calibration assert instrument uniformity transfer primary / secondary standards to the SNLS ﬁelds cross-calibration of SNLS ﬁelds and SDSS Southern Strip lab calibration Improve distance estimator extend wavelength coverage below 300nm Increase Statistics weather permitting Improve Cosmology (?) depends on the quality of the nearby SN sample

Public list of candidates: http://legacy.astro.utoronto.ca

Sept. 2006 Telescope SNIa (/?) SNII (/?) Total SN (/?) Other Total

Gemini 96 9 151 0 151 Keck 77 21 139 4 143 VLT 120 22 235 13 248 Total 293 52 525 17 542

∼ 300 Identiﬁed Type Ia Supernovae on disk

∼ 500 Identiﬁed Type Ia Supernovae at the end of the Survey

SALT2: J. Guy et al (in prep) Use photometric and spectroscopic data PCA to describe SN variability Derive model uncertainties Modeling of SN Ia SED in the far UV

SNLS-04D3gx

g r i z Flux

53100 53150 53200 MJD

Nicolas Regnault [email protected] Measuring the Cosmological Parameters with theSupernova Legacy Survey Same cosmology σ(w) reduced by ∼ 20%

Introduction Analysis of the First Year Dataset The Supernova Legacy Survey Systematics Photometric Calibration of the SNLS Fields Ongoing Work Conclusion SALT2

44 44 SNLS 1st Year 42 42

40 40 B B µ µ 38 38

Ω Ω 36 ( m, Λ)=(0.26,0.74) 36 (Ω ,ΩΛ)=(0.26,0.74) Ω Ω m ( m, Λ)=(1.00,0.00) 34 34 0.2 0.4 0.6 0.8 1 0.2 0.4 0.6 0.8 1 SN Redshift SN Redshift

1 1 ) ) 0 0 H H -1 0.5 -1 0.5 c c L L ( d ( d

10 0 10 0 - 5 log - 5 log

B -0.5 B -0.5 µ µ

-1 0.2 0.4 0.6 0.8 1 -1 0.2 0.4 0.6 0.8 1 SN Redshift SN Redshift Nicolas Regnault [email protected] Measuring the Cosmological Parameters with theSupernova Legacy Survey Introduction Analysis of the First Year Dataset The Supernova Legacy Survey Systematics Photometric Calibration of the SNLS Fields Ongoing Work Conclusion SALT2

44 44 SNLS 1st Year 42 42

40 40 B B µ µ 38 Same cosmology 38

Ω Ω 36 ( m, Λ)=(0.26,0.74) 36 (Ω ,ΩΛ)=(0.26,0.74) σ(w) reducedΩ byΩ ∼ 20% m ( m, Λ)=(1.00,0.00) 34 34 0.2 0.4 0.6 0.8 1 0.2 0.4 0.6 0.8 1 SN Redshift SN Redshift

1 1 ) ) 0 0 H H -1 0.5 -1 0.5 c c L L ( d ( d

10 0 10 0 - 5 log - 5 log

B -0.5 B -0.5 µ µ

-1 0.2 0.4 0.6 0.8 1 -1 0.2 0.4 0.6 0.8 1 SN Redshift SN Redshift Nicolas Regnault [email protected] Measuring the Cosmological Parameters with theSupernova Legacy Survey Introduction Motivations The Supernova Legacy Survey Analysis of the Photometric Grid Photometric Calibration of the SNLS Fields The E98/E95 Program Conclusion Outline

1 Introduction Type Ia Supernovae Measuring the Cosmological Parameters Measuring the Dark Energy Equation of State

2 The Supernova Legacy Survey Analysis of the First Year Dataset Systematics Ongoing Work

3 Photometric Calibration of the SNLS Fields Motivations Analysis of the Photometric Grid The E98/E95 Program

4 Conclusion

Nicolas Regnault [email protected] Measuring the Cosmological Parameters with theSupernova Legacy Survey Introduction Motivations The Supernova Legacy Survey Analysis of the Photometric Grid Photometric Calibration of the SNLS Fields The E98/E95 Program Conclusion Motivations

(From Astier et al, 2006)

Band zero-point shift δΩm (ﬂat) δΩtoto δw (ﬁxedΩm) g 0.01 0.000 -0.02 0.00 r 0.01 0.009 0.03 0.02 i 0.01 -0.014 0.17 -0.04 z 0.03 0.018 -0.48 -0.03 sum - 0.024 0.51 0.05

Internal Calibration linearity stability uniformity Passband models Megacam passbands Landolt and SDSS eﬀective passbands Calibration path ﬂux calibration (intercalibration of Megacam passbands) investigate how the Landolt system is tied to Vega ultimately rely on HST (CALSPEC) spectrophotometric standards, instead of Vega

11.5 Modeling the non-uniformities of the

DEC (deg) photometric response 11 Plate scale variations scattered light 10.5 Dense stellar ﬁelds (RA=20:00:00, DEC=10:00:00)

10 13 dithered exposures variable steps: ∼ 100 pixels → half a camera

9.5 Reobserved after each significant modification of the optics 299.5 300 300.5 301 301.5 RA (deg) No control observations grid corrections applied to the pixels by the Elixir pipeline (scatter flats or photometric flats)

Each CCD is divided into 4 × 9 cells ∼ 50, 000 − 100, 000, isolated, well measured stars, each observed on ∼6 (3 – 12) cells We use the star ﬂux measurements to measure:

an intercalibration coeﬃcient w.r.t. the reference cell, δzpcell a possible color term drift w.r.t the reference cell, δkcell Model

m(star, cell) = m(star) + δzp(cell) [+δk(cell) × col(star)]

Large ﬁt ! 1295 (δzp) – 2590 (δzp + δk) calibration parameters ∼ 100, 000 star ﬂuxes (known only on the reference cell)

FIT FIT 4 4 ccd ccd 0.08 0.1

0.07 3 3 0.06 0.08

0.05

0.06 2 0.04 2

0.03 0.04

0.02 1 1 0.02 0.01

0 0 0 0 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 ccd ccd

2003B 2005B

FIT FIT

4 4 0.06 ccd ccd 0.025 0.05

3 0.02 3 0.04

0.03 0.015 2 2 0.02

0.01

0.01 1 1 0.005 0

0 -0.01 0 0 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 ccd ccd

2003B 2005B

FIT FIT 4 4

ccd 0.02 ccd 0.02

0.01 3 3 0.01

0 0

2 -0.01 2 -0.01

-0.02 -0.02

1 1 -0.03 -0.03

-0.04 -0.04

0 0 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 ccd ccd

2003B 2005B

FIT FIT 4 4

ccd 0.01 ccd 0

0 -0.01 3 3

-0.01 -0.02

2 -0.02 2 -0.03

-0.03 -0.04 1 1 -0.04

-0.05

-0.05 0 0 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 ccd ccd

2003B 2005B

FIT FIT

4 0.015 4

ccd ccd 0.02 0.01

0.005 3 3 0.01 0

-0.005 -0

2 -0.01 2

-0.01 -0.015

-0.02 1 1 -0.02 -0.025

-0.03 -0.03

0 0 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 ccd ccd

2003B 2005B

FIT FIT 4 4 ccd ccd 0.01 0

0 -0.01 3 3

-0.01 -0.02

-0.02 -0.03 2 2

-0.04 -0.03

-0.05 1 -0.04 1

-0.06 -0.05

-0.07 0 0 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 ccd ccd

2003B 2005B

FIT FIT

4 4 0.16 ccd ccd 0.02 0.14

0.12 3 0 3

0.1

-0.02 2 2 0.08

0.06

-0.04

0.04 1 1

-0.06 0.02

0 0 0 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 ccd ccd

2003B 2005B

Photometric Distorsion FIT 4 4 0.01 ccd ccd 0.008 0 0 0.006 3 -0.01 3

-0.02 0.004 -0.02 0.002 -0.03

2 2 -0.04 0 -0.04

-0.05

-0.06 1 -0.06 1

-0.07

-0.08 -0.08 0 0 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 200 400 600 800 1000 1200 1400 ccd ccd Cell number Color terms FIT 4 4 0.01 0.04 ccd ccd

0.04 0.035

3 0.03 3 0.005 0.03

0.025

0.02 2 2 0.02 0

0.015

0.01 0.01 1 1

0.005

0 0 -0.01 0 0 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 200 400 600 800 1000 1200 1400 ccd ccd Cell Number

The bad news Residual non-uniformities in the Elixir-corrected data, at the level of ∼ 2 − 3% Large (unexpected) non-uniformities of the passbands seem to follow a radial pattern 4 to 5% in all bands (4 to 5 nm) cannot be corrected at the pixel level (!)

The good news we can target a uniformity of a few mmag should be checked using additional (dithered) observations (SDSS Southern Strip)

A big Thanks to Jean-Charles for his help !

0.6

0.5

0.4 flux (arbitrary units) 0.3

0.2

0.1

0 400 500 600 700 800 900 1000 1100 lambda (nm)

SDSS−ES

SNLS SDSS−2.5

HST SDSS−PT

Landolt Smith

Vega AB

Goal: Secure a ﬂux calibration of the Megacam survey Cosmology w/ SNe Ia Photometric redshifts and Galaxy SED modeling Stellar physics

1 E98 Observing Group: 2 band observations of

0.5 A DEEP ﬁeld

0 A Landolt/Smith ﬁeld SDSS Southern Strip -0.5 w/ Very Large Dithering pattern

-1 -1 -0.5 0 0.5 1 2+ HST spectrophotometric standards

It will allow us to: check the imager uniformity secure a good intercalibration with the SDSS 2.5-m system compute the colors of Vega in the Landolt system (flux calibration of the Landolt system) define a natural, flux calibrated system for the survey

Test OGs taken on 2006-08-30: 1 OG ∼ 55mn gr, ri, iz, ru blocks scheduled for each of the DEEP ﬁelds SDSS Southern Strip observable until end of January (!)

SNLS is doing well ∼ 300 identiﬁed SNe Ia on disk ∼ 500 identiﬁed SNe Ia at the end of the survey (mid-2008) impact of wheather on data taking (!)

Calibration studies under way Goals precision ≤ 1% of the internal calibration precision ≤ 1% of the calibration w.r.t. HST standards investigate the colors of Vega in the Landolt system heavily rely on the E98/E95 program Instrumental calibration under study

Nicolas Regnault [email protected] Measuring the Cosmological Parameters with theSupernova Legacy Survey