Experimental checking of the Rician statistics in partially compensated wavefronts

Cagigal, Manuel P.; Canales, Vidal F.

doi:10.1117/1.1417495

Cited by 16 publications

(9 citation statements)

References 23 publications

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“…Originally derived by Goodman (1975), and experimentally verified by Cagigal & Canales (2001) and Fitzgerald & Graham (2006), the underlying PDF that estimates the intensity distribution of off-axis stellar speckles in the image plane can be given by a modified Rician (MR) For a sequence of exposures shorter than the decorrelation time of atmospheric speckles (∼10 ms), a histogram of the image plane intensity follows an MR: I C and I S determined for each pixel in an image (Fitzgerald & Graham 2006). Because MEC stores the arrival time information of every photon, all time binning can be done in postprocessing, which is important since the bin size that ideally samples the MR distribution is difficult to determine a priori and may vary across the image.…”

Section: Stochastic Speckle Discrimination (Ssd) Analysismentioning

confidence: 87%

SCExAO/MEC and CHARIS Discovery of a Low-mass, 6 au Separation Companion to HIP 109427 Using Stochastic Speckle Discrimination and High-contrast Spectroscopy*

Steiger

Currie

Brandt

et al. 2021

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Section: Stochastic Speckle Discrimination (Ssd) Analysismentioning

confidence: 87%

SCExAO/MEC and CHARIS Discovery of a Low-mass, 6 au Separation Companion to HIP 109427 Using Stochastic Speckle Discrimination and High-contrast Spectroscopy*

Steiger

Currie

Brandt

et al. 2021

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show abstract

“…Originally derived by Goodman (1975), and experimentally verified by Cagigal & Canales (2001) and Fitzgerald & Graham (2006), the underlying probability density function that estimates the intensity distri-bution of off-axis stellar speckles in the image plane can be given by a modified Rician (MR)…”

Section: Stochastic Speckle Discrimination (Ssd) Analysismentioning

confidence: 96%

SCExAO/MEC and CHARIS Discovery of a Low Mass, 6 AU-Separation Companion to HIP 109427 using Stochastic Speckle Discrimination and High-Contrast Spectroscopy

Steiger,

Currie,

Brandt

et al. 2021

Preprint

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We report the direct imaging discovery of a low-mass companion to the nearby accelerating A star, HIP 109427, with the Subaru Coronagraphic Extreme Adaptive Optics (SCExAO) instrument coupled with the MKID Exoplanet Camera (MEC) and CHARIS integral field spectrograph. CHARIS data reduced with reference star PSF subtraction yield 1.1-2.4 µm spectra. MEC reveals the companion in Y and J band at a comparable signal-to-noise ratio using stochastic speckle discrimination, with no PSF subtraction techniques. Combined with complementary follow-up L p photometry from Keck/NIRC2, the SCExAO data favors a spectral type, effective temperature, and luminosity of M4-M5.5, 3000-3200 K, and log 10 (L/L ) = −2.28 +0.04 −0.04 , respectively. Relative astrometry of HIP 109427 B from SCExAO/CHARIS and Keck/NIRC2, and complementary Gaia-Hipparcos absolute astrometry of the primary favor a semimajor axis of 6.55 +3.0 −0.48 au, an eccentricity of 0.54 +0.28 −0.15 , an inclination of 66.7 +8.5 −14 degrees, and a dynamical mass of 0.280 +0.18 −0.059 M . This work shows the potential for extreme AO systems to utilize speckle statistics in addition to widely-used post-processing methods to directly image faint companions to nearby stars near the telescope diffraction limit.

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“…As noted by AS04, this behavior is described by the theoretical distribution of intensity originally de-rived by Goodman (1975) (see also Goodman 1985). Cagigal & Canales (2001) observed this distribution in a laboratory setting, using a spatial light modulator to simultaneously simulate turbulence and partial correction with AO.…”

Section: Introductionmentioning

confidence: 92%

Speckle Statistics in Adaptively Corrected Images

Fitzgerald

Graham

2006

ApJ

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(abridged) Imaging observations are generally affected by a fluctuating background of speckles, a particular problem when detecting faint stellar companions at small angular separations. Knowing the distribution of the speckle intensities at a given location in the image plane is important for understanding the noise limits of companion detection. The speckle noise limit in a long-exposure image is characterized by the intensity variance and the speckle lifetime. In this paper we address the former quantity through the distribution function of speckle intensity. Previous theoretical work has predicted a form for this distribution function at a single location in the image plane. We developed a fast readout mode to take short exposures of stellar images corrected by adaptive optics at the ground-based UCO/Lick Observatory, with integration times of 5 ms and a time between successive frames of 14.5 ms ($\lambda=2.2$ $\mu$m). These observations temporally oversample and spatially Nyquist sample the observed speckle patterns. We show, for various locations in the image plane, the observed distribution of speckle intensities is consistent with the predicted form. Additionally, we demonstrate a method by which $I_c$ and $I_s$ can be mapped over the image plane. As the quantity $I_c$ is proportional to the PSF of the telescope free of random atmospheric aberrations, this method can be used for PSF calibration and reconstruction.Comment: 7 pages, 4 figures, ApJ accepte

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Experimental checking of the Rician statistics in partially compensated wavefronts

Cited by 16 publications

References 23 publications

SCExAO/MEC and CHARIS Discovery of a Low-mass, 6 au Separation Companion to HIP 109427 Using Stochastic Speckle Discrimination and High-contrast Spectroscopy*

SCExAO/MEC and CHARIS Discovery of a Low-mass, 6 au Separation Companion to HIP 109427 Using Stochastic Speckle Discrimination and High-contrast Spectroscopy*

SCExAO/MEC and CHARIS Discovery of a Low Mass, 6 AU-Separation Companion to HIP 109427 using Stochastic Speckle Discrimination and High-Contrast Spectroscopy

Speckle Statistics in Adaptively Corrected Images

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