We employ electrostatic conversion drift calculations to match CCD pixel signal covariances observed in flat field exposures acquired using candidate sensor devices for the LSST Camera. We thus constrain pixel geometry distortions present at the end of integration, based on signal images recorded. We use available data from several operational voltage parameter settings to validate our understanding. Our primary goal is to optimize flux point-spread function (FPSF) estimation quantitatively, and thereby minimize sensor-induced errors which may limit performance in precision astronomy applications. We consider alternative compensation scenarios that will take maximum advantage of our understanding of this underlying mechanism in data processing pipelines currently under development. To quantitatively capture the pixel response in high-contrast/high dynamic range operational extrema, we propose herein some straightforward laboratory tests that involve altering the time order of source illumination on sensors, within individual test exposures. Hence the word {\it hysteretic} in the title of this paper.

Maxima and minima

SIGNAL (programming language)

Point spread function

High fidelity

10.1117/12.2234482

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Citations (3)

Measurement of the polarization in charged current interactions in the NOMAD experiment

Nuclear Physics B (2000)

P. Astier D. Autiero A. Baldisseri M. Baldo‐Ceolin M. Banner

Momentum transfer

Charged current

Bubble chamber

10.1016/s0550-3213(00)00503-4

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Citations (79)

A precision measurement of charm dimuon production in neutrino interactions from the NOMAD experiment

Nuclear Physics B (2013)

O. Samoylov R. Petti S. Alekhin P. Astier D. Autiero

Charm (quantum number)

Charm quark

Strange quark

Charged current

10.1016/j.nuclphysb.2013.08.021

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Citations (72)

RAPIDLY RISING TRANSIENTS IN THE SUPERNOVA—SUPERLUMINOUS SUPERNOVA GAP

The Astrophysical Journal (2016)

I. Arcavi William M. Wolf D. A. Howell Lars Bildsten G. Leloudas

We present observations of four rapidly rising (t_{rise}~10d) transients with peak luminosities between those of supernovae (SNe) and superluminous SNe (M_{peak}~-20) - one discovered and followed by the Palomar Transient Factory (PTF) and three by the Supernova Legacy Survey (SNLS). The light curves resemble those of SN 2011kl, recently shown to be associated with an ultra-long-duration gamma ray burst (GRB), though no GRB was seen to accompany our SNe. The rapid rise to a luminous peak places these events in a unique part of SN phase space, challenging standard SN emission mechanisms. Spectra of the PTF event formally classify it as a Type II SN due to broad Halpha emission, but an unusual absorption feature, which can be interpreted as either high velocity Halpha (though deeper than in previously known cases) or Si II (as seen in Type Ia SNe), is also observed. We find that existing models of white dwarf detonations, CSM interaction, shock breakout in a wind (or steeper CSM) and magnetar spindown can not readily explain the observations. We consider the possibility that a "Type 1.5 SN" scenario could be the origin of our events. More detailed models for these kinds of transients and more constraining observations of future such events should help better determine their nature.

Magnetar

10.3847/0004-637x/819/1/35

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Citations (81)

Point sources and astrometry (cont.)

P. Astier

Astrometry

Source

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Citations (0)

Dark-energy constraints and correlations with systematics from CFHTLS weak lensing, SNLS supernovae Ia and WMAP5

Astronomy and Astrophysics (2009)

M. Kilbinger K. Benabed J. Guy P. Astier I. Tereno

Aims. We combine measurements of weak gravitational lensing from the CFHTLS-Wide survey, supernovae Ia from CFHT SNLS and CMB anisotropies from WMAP5 to obtain joint constraints on cosmological parameters, in particular, the dark-energy equation-of-state parameter w. We assess the influence of systematics in the data on the results and look for possible correlations with cosmological parameters.Methods. We implemented an MCMC algorithm to sample the parameter space of a flat CDM model with a dark-energy component of constant w. Systematics in the data are parametrised and included in the analysis. We determine the influence of photometric calibration of SNIa data on cosmological results by calculating the response of the distance modulus to photometric zero-point variations. The weak lensing data set is tested for anomalous field-to-field variations and a systematic shape measurement bias for high-redshift galaxies.Results. Ignoring photometric uncertainties for SNLS biases cosmological parameters by at most 20% of the statistical errors, using supernovae alone; the parameter uncertainties are underestimated by 10%. The weak-lensing field-to-field variance between 1 deg^{2^{-MegaCam pointings is 5-15% higher than predicted from N-body simulations. We find no bias in the lensing signal at high redshift, within the framework of a simple model, and marginalising over cosmological parameters. Assuming a systematic underestimation of the lensing signal, the normalisation increases by up to 8%. Combining all three probes we obtain at 68% confidence ( at 95%), including systematic errors. Our results are therefore consistent with the cosmological constant Λ. Systematics in the data increase the error bars by up to 35%; the best-fit values change by less than 0.15σ.}}

Cosmological constant

Photometric redshift

10.1051/0004-6361/200811247

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Citations (100)

The Host Galaxies of Type Ia Supernovae at High Redshift

American Astronomical Society Meeting Abstracts (2002)

R. Quimby G. Aldering P. Nugent R. Amanullah P. Astier

Source

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'Imaka: a one-degree high-resolution imager for the Canada-France-Hawaii Telescope

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE (2010)

Mark Chun R. G. Carlberg Harvey B. Richer Y. Mellier P. Astier

The 'Imaka project is a high-resolution wide-field imager proposed for the Canada-France-Hawaii telescope (CFHT) on Mauna Kea. 'Imaka takes advantage of two features of the optical turbulence above Mauna Kea: weak optical turbulence in the free-atmosphere and boundary layer turbulence which is highly confined within a surface layer tens of meters thick and or the telescope enclosures. The combination of the two allows a groundlayer adaptive optics system (GLAO) to routinely deliver an extremely-wide corrected field of view of one-degree at an excellent free-atmosphere seeing limit at visible wavelengths. In addition, populating the focal-plane with orthogonal-transfer CCDs provides a second level of image improvement on the free-atmosphere seeing and the residual GLAO correction. The impact of such an instrument covers a broad range of science and is a natural progression of CFHT's wide-field expertise.

Field of view

Atmospheric optics

10.1117/12.857570

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Citations (1)

The core-collapse rate from the Supernova Legacy Survey

Astronomy and Astrophysics (2009)

G. Bazin N. Palanque‐Delabrouille J. Rich V. Ruhlmann-Kleider É. Aubourg

We use three years of data from the Supernova Legacy Survey (SNLS) to study the general properties of core-collapse and type Ia supernovae. This is the first such study using the "rolling search" technique which guarantees well-sampled SNLS light curves and good efficiency for supernovae brighter than $i^\prime\sim24$. Using host photometric redshifts, we measure the supernova absolute magnitude distribution down to luminosities $4.5 {\rm mag}$ fainter than normal SNIa. Using spectroscopy and light-curve fitting to discriminate against SNIa, we find a sample of 117 core-collapse supernova candidates with redshifts $z<0.4$ (median redshift of 0.29) and measure their rate to be larger than the type Ia supernova rate by a factor $4.5\pm0.8(stat.) \pm0.6 (sys.)$. This corresponds to a core-collapse rate at $z=0.3$ of $[1.42\pm 0.3(stat.) \pm0.3(sys.)]\times10^{-4}\yr^{-1}(h_{70}^{-1}\Mpc)^{-3}$.

Type II supernova

Absolute magnitude

10.1051/0004-6361/200911847

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Citations (130)