Увійти

Готові списки джерел за темами / Lyot coronagraph / Статті в журналах

Статті в журналах з теми "Lyot coronagraph"

Щоб переглянути інші типи публікацій з цієї теми, перейдіть за посиланням: Lyot coronagraph.

Автор: Grafiati

Опубліковано: 7 липня 2024

Оформте джерело за APA, MLA, Chicago, Harvard та іншими стилями

Оберіть тип джерела:

Ознайомтеся з топ-50 статей у журналах для дослідження на тему "Lyot coronagraph".

Біля кожної праці в переліку літератури доступна кнопка «Додати до бібліографії». Скористайтеся нею – і ми автоматично оформимо бібліографічне посилання на обрану працю в потрібному вам стилі цитування: APA, MLA, «Гарвард», «Чикаго», «Ванкувер» тощо.

Також ви можете завантажити повний текст наукової публікації у форматі «.pdf» та прочитати онлайн анотацію до роботи, якщо відповідні параметри наявні в метаданих.

Переглядайте статті в журналах для різних дисциплін та оформлюйте правильно вашу бібліографію.

1

Leboulleux, Lucie, Alexis Carlotti, and Mamadou N’Diaye. "Redundant apodization for direct imaging of exoplanets." Astronomy & Astrophysics 659 (March 2022): A143. http://dx.doi.org/10.1051/0004-6361/202142410.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

Context. Direct imaging and spectroscopy of Earth-like planets and young Jupiters require contrast values up to 106−1010 at angular separations of a few dozen milliarcseconds. To achieve this goal, one of the most promising approaches consists of using large segmented primary mirror telescopes with coronagraphic instruments. While they are able to reach high contrast at small angular separations, coronagraphs are highly sensitive to wavefront errors, however. The segmentation itself is responsible for phasing errors and segment-level vibrations that have to be controlled at a subnanometric accuracy. Aims. We propose an innovative method for a coronagraph design that allows a consequent relaxation of the segment phasing and stability constraints for low segment-count mirrors and generates an instrument that is more robust to segment-level wavefront errors. Methods. This method is based on an optimization of the coronagraph design that includes a segment-level apodization. This is repeated over the pupil to match the segmentation redundancy and improves the contrast stability beyond the minimum separation set by the single-segment diffraction limit. Results. We validate this method on a Giant Magellan Telescope (GMT)-like pupil (seven circular segments) for two coronagraph types: apodized pupil Lyot coronagraphs, and apodizing phase plate coronagraphs. For the apodized pupil Lyot coronagraphs, redundant apodization enables releasing the piston phasing constraints by a factor of 5-20 compared to classical designs. For the apodizing phase plate coronagraphs, the contrast remains almost constant up to 1 radian RMS of the phasing errors. We also show that redundant apodizations increase the robustness of the coronagraph to segment tip-tilt errors, as well as to missing segment errors. Conclusions. Redundant apodization enables reducing or even removing any constraints on the primary mirror segment phasing at the price of larger angular separations and lower throughputs. This method cannot be applied to higher-segment count mirrors such as the ELT or the TMT, but it is particularly suitable for low segment-count mirrors (fewer than ~20 segments) such as the GMT aperture. These mirrors aim for high-contrast imaging of debris disks or exoplanets down to 100 mas.

2

Kim, I. S., and O. I. Bugaenko. "On magnetic measurements in prominences." Proceedings of the International Astronomical Union 8, S300 (June 2013): 426–27. http://dx.doi.org/10.1017/s1743921313011393.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

AbstractThe successes of magnetic measurements in faint objects located near very bright ones are strongly depending on the stray light in the telescope. We propose a mask with a variable transmission placed on the primary optics of a telescope. Our computations of the stray light in such a telescope indicate that the calculated coronagraphic factor of improvement, K, would increase at least by 2 orders of magnitude compared to the Lyot-type coronagraph.

3

Anche, Ramya M., Ewan Douglas, Kian Milani, Jaren Ashcraft, Maxwell A. Millar-Blanchaer, John H. Debes, Julien Milli, and Justin Hom. "Simulation of High-contrast Polarimetric Observations of Debris Disks with the Roman Coronagraph Instrument." Publications of the Astronomical Society of the Pacific 135, no. 1054 (December 1, 2023): 125001. http://dx.doi.org/10.1088/1538-3873/ad0a72.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

Abstract The Nancy Grace Roman Space Telescope Coronagraph Instrument will enable the polarimetric imaging of debris disks and inner dust belts in the optical and near-infrared wavelengths, in addition to the high-contrast polarimetric imaging and spectroscopy of exoplanets. The Coronagraph uses two Wollaston prisms to produce four orthogonally polarized images and is expected to measure the polarization fraction with measurement errors <3% per spatial resolution element. To simulate the polarization observations through the Hybrid Lyot Coronagraph (HLC) and Shaped Pupil Coronagraph (SPC), we model disk scattering, the coronagraphic point-response function, detector noise, speckles, jitter, and instrumental polarization and calculate the Stokes parameters. To illustrate the potential for discovery and a better understanding of known systems with both the HLC and SPC modes, we model the debris disks around Epsilon Eridani and HR 4796A, respectively. For Epsilon Eridani, using astrosilicates with 0.37 ± 0.01 as the peak input polarization fraction in one resolution element, we recover the peak disk polarization fraction of 0.33 ± 0.01. Similarly, for HR 4796A, for a peak input polarization fraction of 0.92 ± 0.01, we obtain the peak output polarization fraction as 0.80 ± 0.03. The Coronagraph design meets the required precision, and forward modeling is needed to accurately estimate the polarization fraction.

4

Carbillet, Marcel, Philippe Bendjoya, Lyu Abe, Géraldine Guerri, Anthony Boccaletti, Jean-Baptiste Daban, Kjetil Dohlen, et al. "Apodized Lyot coronagraph for SPHERE/VLT." Experimental Astronomy 30, no. 1 (March 24, 2011): 39–58. http://dx.doi.org/10.1007/s10686-011-9219-4.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

5

Rougeot, R., R. Flamary, D. Mary, and C. Aime. "Influence of surface roughness on diffraction in the externally occulted Lyot solar coronagraph." Astronomy & Astrophysics 626 (June 2019): A1. http://dx.doi.org/10.1051/0004-6361/201834634.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

Context. The solar coronagraph ASPIICS will fly on the future ESA formation flying mission Proba-3. The instrument combines an external occulter of diameter 1.42 m and a Lyot solar coronagraph of 5 cm diameter, located downstream at a distance of 144 m. Aims. The theoretical performance of the externally occulted Lyot coronagraph has been computed by assuming perfect optics. In this paper, we improve related modelling by introducing roughness scattering effects from the telescope. We have computed the diffraction at the detector, that we compare to the ideal case without perturbation to estimate the performance degradation. We have also investigated the influence of sizing the internal occulter and the Lyot stop, and we performed a sensitivity analysis on the roughness. Methods. We have built on a recently published numerical model of diffraction propagation. The micro-structures of the telescope are built by filtering a white noise with a power spectral density following an isotropic ABC function, suggested by Harvey scatter theory. The parameters were tuned to fit experimental data measured on ASPIICS lenses. The computed wave front error was included in the Fresnel wave propagation of the coronagraph. A circular integration over the solar disk was performed to reconstruct the complete diffraction intensity. Results. The level of micro-roughness is 1.92 nm root-mean-square. Compared to the ideal case, in the plane of the internal occulter, the diffraction peak intensity is reduced by ≃0.001%. However, the intensity outside the peak increases by 12% on average, up to 20% at 3 R⊙, where the mask does not filter out the diffraction. At detector level, the diffraction peak remains ≃10−6 at 1.1 R⊙, similar to the ideal case, but the diffraction tail at large solar radius is much higher, up to one order of magnitude. Sizing the internal occulter and the Lyot stop does not improve the rejection, as opposed to the ideal case. Conclusions. Besides these results, this paper provides a methodology to implement roughness scattering in the wave propagation model for the solar coronagraph.

6

Leboulleux, Lucie, Jean-François Sauvage, Rémi Soummer, Thierry Fusco, Laurent Pueyo, Laurent M. Mugnier, Christopher Moriarty, Peter Petrone, and Keira Brooks. "Experimental validation of coronagraphic focal-plane wavefront sensing for future segmented space telescopes." Astronomy & Astrophysics 639 (July 2020): A70. http://dx.doi.org/10.1051/0004-6361/202037658.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

Context. Direct imaging of Earth-like planets from space requires dedicated observatories, combining large segmented apertures with instruments and techniques such as coronagraphs, wavefront sensors, and wavefront control in order to reach the high contrast of 1010 that is required. The complexity of these systems would be increased by the segmentation of the primary mirror, which allows for the larger diameters necessary to image Earth-like planets but also introduces specific patterns in the image due to the pupil shape and segmentation and making high-contrast imaging more challenging. Among these defects, the phasing errors of the primary mirror are a strong limitation to the performance. Aims. In this paper, we focus on the wavefront sensing of segment phasing errors for a high-contrast system, using the COronagraphic Focal plane wave-Front Estimation for Exoplanet detection (COFFEE) technique. Methods. We implemented and tested COFFEE on the High-contrast imaging for Complex Aperture Telescopes (HiCAT) testbed, in a configuration without any coronagraph and with a classical Lyot coronagraph, to reconstruct errors applied on a 37 segment mirror. We analysed the quality and limitations of the reconstructions. Results. We demonstrate that COFFEE is able to estimate correctly the phasing errors of a segmented telescope for piston, tip, and tilt aberrations of typically 100 nm RMS. We also identified the limitations of COFFEE for the reconstruction of low-order wavefront modes, which are highly filtered by the coronagraph. This is illustrated using two focal plane mask sizes on HiCAT. We discuss possible solutions, both in the hardware system and in the COFFEE optimizer, to mitigate these issues.

7

Trauger, John, Dwight Moody, John Krist, and Brian Gordon. "Hybrid Lyot coronagraph for WFIRST-AFTA: coronagraph design and performance metrics." Journal of Astronomical Telescopes, Instruments, and Systems 2, no. 1 (January 14, 2016): 011013. http://dx.doi.org/10.1117/1.jatis.2.1.011013.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

8

Soummer, R., L. Pueyo, A. Sivaramakrishnan, and R. J. Vanderbei. "Fast computation of Lyot-style coronagraph propagation." Optics Express 15, no. 24 (2007): 15935. http://dx.doi.org/10.1364/oe.15.015935.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

9

Loutsenko, Igor, and Oksana Yermolayeva. "Quasi-Band-Limited Coronagraph for Extended Sources." Journal of Astronomical Instrumentation 10, no. 01 (February 10, 2021): 2150002. http://dx.doi.org/10.1142/s2251171721500021.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

We propose a class of graded coronagraphic “amplitude” image masks for a high throughput Lyot-type coronagraph that transmits light from an annular region around an extended source and suppresses light, with extremely high ratio, from elsewhere. The interior radius of the region is comparable with its exterior radius. The masks are designed using an idea inspired by approach due M. J. Kuchner and W. A. Traub (“band-limited” masks) and approach to optimal apodization by D. Slepian. One potential application of our masks is direct high-resolution imaging of exo-planets with the help of the Solar Gravitational Lens, where apparent radius of the “Einstein ring” image of a planet is of the order of an arc-second and is comparable with the apparent radius of the sun and solar corona.

10

Xin, Yinzi, Laurent Pueyo, Romain Laugier, Leonid Pogorelyuk, Ewan S. Douglas, Benjamin J. S. Pope, and Kerri L. Cahoy. "Coronagraphic Data Post-processing Using Projections on Instrumental Modes." Astrophysical Journal 963, no. 2 (March 1, 2024): 96. http://dx.doi.org/10.3847/1538-4357/ad1879.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

Abstract Directly observing exoplanets with coronagraphs is impeded by the presence of speckles from aberrations in the optical path, which can be mitigated in hardware with wave front control, as well as in post-processing. This work explores using an instrument model in post-processing to separate astrophysical signals from residual aberrations in coronagraphic data. The effect of wave front error (WFE) on the coronagraphic intensity consists of a linear contribution and a quadratic contribution. When either of the terms is much larger than the other, the instrument response can be approximated by a transfer matrix mapping WFE to detector plane intensity. From this transfer matrix, a useful projection onto instrumental modes that removes the dominant error modes can be derived. We apply this approach to synthetically generated Roman Space Telescope hybrid Lyot coronagraph data to extract “robust observables,” which can be used instead of raw data for applications such as detection testing. The projection improves planet flux ratio detection limits by about 28% in the linear regime and by over a factor of 2 in the quadratic regime, illustrating that robust observables can increase sensitivity to astrophysical signals and improve the scientific yield from coronagraphic data. While this approach does not require additional information such as observations of reference stars or modulations of a deformable mirror, it can and should be combined with these other techniques, acting as a model-informed prior in an overall post-processing strategy.

11

Aime, C. "Principle of an Achromatic Prolate Apodized Lyot Coronagraph." Publications of the Astronomical Society of the Pacific 117, no. 835 (September 2005): 1012–19. http://dx.doi.org/10.1086/432687.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

12

Martinez, P., A. Boccaletti, M. Kasper, P. Baudoz, and C. Cavarroc. "Optimization of apodized pupil Lyot coronagraph for ELTs." Astronomy & Astrophysics 474, no. 2 (August 28, 2007): 671–78. http://dx.doi.org/10.1051/0004-6361:20077708.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

13

Vigan, A., M. N’Diaye, K. Dohlen, J. F. Sauvage, J. Milli, G. Zins, C. Petit, et al. "Calibration of quasi-static aberrations in exoplanet direct-imaging instruments with a Zernike phase-mask sensor." Astronomy & Astrophysics 629 (August 26, 2019): A11. http://dx.doi.org/10.1051/0004-6361/201935889.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

Second-generation exoplanet imagers using extreme adaptive optics (ExAO) and coronagraphy have demonstrated their great potential for studying close circumstellar environments and for detecting new companions and helping to understand their physical properties. However, at very small angular separation, their performance in contrast is limited by several factors: diffraction by the complex telescope pupil (central obscuration and spiders) not perfectly canceled by the coronagraph, residual dynamic wavefront errors, chromatic wavefront errors, and wavefront errors resulting from noncommon path aberrations (NCPAs). These latter are differential aberrations between the visible wavefront sensing path of the ExAO system and the near-infrared science path in which the coronagraph is located. In a previous work, we demonstrated the use of a Zernike wavefront sensor called ZELDA for sensing NCPAs in the VLT/SPHERE exoplanet imager and their compensation with the high-order deformable mirror of the instrument. These early tests on the internal light source led to encouraging results for the attenuation of the quasi-static speckles at very small separation. In the present work, we move to the next step with the on-sky validation of NCPA compensation with ZELDA. With an improved procedure for the compensation of NCPAs, we start by reproducing previous results on the internal source. We show that the amount of aberration integrated between 1 and 15 cycles/pupil (c/p) is decreased by a factor of approximately five, which translates into a gain in raw contrast of between 2 and 3 at separations below 300 mas. On sky, we demonstrate that NCPA compensation works in closed loop, leading to an attenuation of the amount of aberration by a factor of approximately two. However, we identify a loss of sensitivity for the sensor that is only partly explained by the difference in Strehl ratio between the internal and on-sky measurements. Our simulations show that the impact of ExAO residuals on ZELDA measurements is negligible for integration times beyond a few tenths of a second. Coronagraphic imaging on sky is improved in raw contrast by a factor of 2.5 at most in the ExAO-corrected region. We use coronagraphic image reconstruction based on a detailed model of the instrument to demonstrate that both internal and on-sky raw contrasts can be precisely explained, and we establish that the observed performance after NCPA compensation is no longer limited by an improper compensation for aberration but by the current apodized-pupil Lyot coronagraph design. We finally conclude that a coronagraph upgrade combined to a proper NCPA compensation scheme could easily bring a gain in raw contrast of a factor of two to three below 200 mas.

14

CHI, Jinpeng, Hongxin ZHANG, Xiaodong WANG, Qingyu MENG, Zichang QIN, Yunhui LI, Taisheng WANG, and Fengyou Li. "Optical system and stray light suppression of Lyot coronagraph." Optics and Precision Engineering 30, no. 17 (2022): 2050–57. http://dx.doi.org/10.37188/ope.20223017.2050.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

15

Soummer, R., B. R. Oppenheimer, S. Hinkley, A. Sivaramakrishnan, R. B. Makidon, A. Digby, D. Brenner, et al. "The Lyot project coronagraph: data processing and performance analysis." EAS Publications Series 22 (2006): 199–212. http://dx.doi.org/10.1051/eas:2006133.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

16

Hufbauer, Karl. "Artificial Eclipses: Bernard Lyot and the Coronagraph, 1929-1939." Historical Studies in the Physical and Biological Sciences 24, no. 2 (January 1, 1994): 337–94. http://dx.doi.org/10.2307/27757726.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

17

Murakami, N., R. Uemura, N. Baba, Y. Sato, J. Nishikawa, and M. Tamura. "Four‐Quadrant Phase Mask Coronagraph with a Jacquinot‐Lyot Stop." Astrophysical Journal 677, no. 2 (April 20, 2008): 1425–32. http://dx.doi.org/10.1086/527668.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

18

Bu Heyang, 卜和阳, 张红鑫 Zhang Hongxin, 卢振武 Lu Zhenwu, and 张正正 Zhang Zhengzheng. "Analysis on the Parameter of Lyot Stop in Internally Occulting Refractive Coronagraph." Acta Optica Sinica 34, no. 12 (2014): 1212006. http://dx.doi.org/10.3788/aos201434.1212006.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

19

Ferrari, André, Claude Aime, and Rémi Soummer. "ANALYTICAL COMPUTATION OF THE LYOT CORONAGRAPH RESPONSE TO AN EXTENDED SOURCE." Astrophysical Journal 708, no. 1 (December 9, 2009): 218–23. http://dx.doi.org/10.1088/0004-637x/708/1/218.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

20

Guerri, Géraldine, Jean-Baptiste Daban, Sylvie Robbe-Dubois, Richard Douet, Lyu Abe, Jacques Baudrand, Marcel Carbillet, et al. "Apodized Lyot coronagraph for SPHERE/VLT: II. Laboratory tests and performance." Experimental Astronomy 30, no. 1 (March 24, 2011): 59–81. http://dx.doi.org/10.1007/s10686-011-9220-y.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

21

Ge, Rui, Hui Zhao, Jing-Xuan Wei, Yong-Qiang Duan, Zhe Bai, Chuang Li, Yuan-Bo Wang, and Xue-Wu Fan. "Improved two-step optimization procedure used for designing an apodizer and Lyot stop in the Lyot coronagraph." Applied Optics 59, no. 16 (May 28, 2020): 4939. http://dx.doi.org/10.1364/ao.391959.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

22

Smartt, Raymond N., Serge Koutchmy, and Jacques-Clair NoëNs. "Near-IR Solar Coronal Observations with New-Technology Reflecting Coronographs." Symposium - International Astronomical Union 154 (1994): 603–8. http://dx.doi.org/10.1017/s0074180900124908.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

Emission-line and K-coronal observations in the IR have the significant advantage of reduced sky brightness compared with the visible, while the effects of seeing are also reduced. Moreover, strong lines are available in the near-IR. Examples of the current capabilities of IR coronal observations using conventional Lyot coronagraphs are discussed briefly. Photometric measurements using the two IR lines of Fe XIII (10,747 Å and 10,798 Å), together with the Fe XIII 3,388 Å line, have provided a valuable electron-density diagnostic, but with low-angular-resolution. The 10,747 Å line has high intrinsic polarization. It has been used for extensive coronal magnetic field measurements, but only the direction of the field, and that with modest angular resolution, has been achieved due basically to flux limitations. Such studies suffer from the lack of high angular resolution and high photon flux. Moreover, the chromatic properties of a singlet objective lens preclude simultaneous observations at widely-differing wavelengths of the important inner coronal region. A coronagraph based on a mirror objective avoids such problems. Further, comparatively high-resolution and high-sensitivity arrays are now available with quantum efficiencies up to 90%. Reflecting coronagraphs with advanced arrays then provide the possibility of obtaining high-resolution images in the infrared to carry out a wide variety of studies crucial to many of the outstanding problems in coronal physics. A program for the development of reflecting coronagraphs is described briefly, with an emphasis on applications to IR coronal studies.

23

Martinez, P. "Fast-modulation imaging with the self-coherent camera." Astronomy & Astrophysics 629 (September 2019): L10. http://dx.doi.org/10.1051/0004-6361/201936496.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

Context. Direct detection of exoplanets requires imaging in a highly dynamic range and exquisite image quality and stability. Wavefront error (atmospheric errors, manufacturing errors on optics, cophasing residuals, temperature variations, etc.) will limit the efficiency of this endeavor by creating various flavors of speckles that evolve with different timescales. Active wavefront-error correction using a deformable mirror requires measuring the wavefront aberrations in the science image with high accuracy and in a shorter time than the duration of the dominant speckle lifetime. Aims. The self-coherent camera (SCC) is a focal plane wavefront sensor exploiting the coherence of light to generate Fizeau fringes in the image plane to spatially encode speckles. The SCC combines a coronagraph and a modified Lyot stop to which a reference channel is added. The conventional SCC is restricted to long-exposure measurements because the light transmitted through the reference channel is limited. The SCC can correct quasi-static aberrations but precludes short-lived atmospheric aberrations from the measurement. Methods. I propose an alternative to the conventional SCC that I call the fast-modulated SCC. It uses a simplified Lyot stop design and an adequate Fourier filtering algorithm. The theory is established and confirmed by means of numerical simulations. Results. The SCC theory dictates that the separation between the classical Lyot stop and the reference channel must be larger than 1.5 times the Lyot stop diameter. The fast-modulated SCC allows for the reference channel to be placed anywhere, in particular in the vicinity of the pupil where the maximum of diffracted light is found. This alternative represents a complete game changer for the sensor: full compatibility with any type of coronagraph, easy installation in existing instruments, and versatility by accessing short- and long-time exposure measurements. Conclusions. While the conventional SCC can almost not be implemented in existing instruments because the optical beam footprint in the instrument must be wide enough to illuminate the reference channel, which is often seen as a significant shortcoming, the fast-modulated SCC does not require any constraint on this. The fast-modulated SCC also relaxes the high sampling requirement to resolve the fringes, which is usually incompatible with the observation of fainter targets because the fringes are larger. The fast-modulated SCC simultaneously counteracts the two original shortcomings of the SCC concept.

24

Rozelot, Jean-Pierre, and Jagdev Singh. "Spectrographic observations of the ionized iron coronal emission lines at Pic du Midi Observatory (F) in the mid-60s." Journal for the History of Astronomy 53, no. 3 (August 2022): 300–327. http://dx.doi.org/10.1177/00218286221101604.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

This paper is dedicated to the memory of Jean Rösch, a great figure in astronomy in the years 1947–1981 who designed, among several innovative devices, a 15-cm spectro-coronagraph. This instrument was installed at Pic du Midi observatory (south-west France), was in use during the mid-60s, fully dedicated to the observation from the ground of the coronal highly ionized iron lines, which was a true challenge at that time. This program is here reconsidered in the context of the time, at Pic du Midi observatory, which has been the cradle of routine visual coronal observations initiated by Bernard Lyot. We take advantage of this review to underline that the goals and objectives of this ground-based coronal program are taken over since 2008, by an Indian team from Bangalore (Indian Institute of Astrophysics), through a space mission (ADITYA-L1 or Sun in Sanskrit), showing a-posteriori the very innovative aspects developed with the help of this 15-cm spectro-coronagraph and thanks to the skills of J. Rösch’s collaborators.

25

Ruane, G. J., E. Huby, O. Absil, D. Mawet, C. Delacroix, B. Carlomagno, and G. A. Swartzlander. "Lyot-plane phase masks for improved high-contrast imaging with a vortex coronagraph." Astronomy & Astrophysics 583 (October 30, 2015): A81. http://dx.doi.org/10.1051/0004-6361/201526561.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

26

Itoh, Satoshi, Taro Matsuo, Shunsuke Ota, Kensuke Hara, Yuji Ikeda, Reiki Kojima, Toru Yamada, and Takahiro Sumi. "Experimental Verification of a One-dimensional Diffraction-limit Coronagraph." Publications of the Astronomical Society of the Pacific 135, no. 1048 (June 1, 2023): 064502. http://dx.doi.org/10.1088/1538-3873/acdbea.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

Abstract We performed an experimental verification of a coronagraph. As a result, we confirmed that, at the focal region where the planetary point spread function exists, the coronagraph system mitigates the raw contrast of a star-planet system by at least 1 × 10−5 even for the 1-λ/D star-planet separation. In addition, the verified coronagraph keeps the shapes of the off-axis point spread functions when the setup has the source angular separation of 1λ/D. The low-order wave front error and the non-zero extinction ratio of the linear polarizer may affect the currently confirmed contrast. The sharpness of the off-axis point spread function generated by the sub-λ/D separated sources is promising for the fiber-based observation of exoplanets. The coupling efficiency with a single mode fiber exceeds 50% when the angular separation is greater than 3–4×10−1 λ/D. For sub-λ/D separated sources, the peak positions (obtained with Gaussian fitting) of the output point spread functions are different from the angular positions of sources; the peak position moved from about 0.8λ/D to 1.0λ/D as the angular separation of the light source varies from 0.1λ/D to 1.0λ/D. The off-axis throughput including the fiber-coupling efficiency (with respect to no focal plane mask) is about 40% for 1-λ/D separated sources and 10% for 0.5-λ/D separated ones (excluding the factor of the ratio of pupil aperture width and Lyot stop width), where we assumed a linear-polarized-light injection. In addition, because this coronagraph can remove point sources on a line in the sky, it has another promising application for high-contrast imaging of exoplanets in binary systems.

27

Dorotovič, I., B. Lukáč, T. Pintér, and M. Rybanský. "A New Station of Prominence Patrol Observations in Slovakia." International Astronomical Union Colloquium 167 (1998): 498–501. http://dx.doi.org/10.1017/s0252921100048168.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

AbstractThe data from prominence observations provide an opportunity to study spatio-temporal distribution of prominences over a solar cycle. The Slovak Central Observatory (SCO) at Hurbanovo (South Slovakia) in cooperation with the coronal station at Lomnický Štít (Astronomical Institute of the Slovak Academy of Sciences, Tatranská Lomnica, Slovakia) constructed a Lyot coronagraph with parameters D/f of 90/1250/3750 mm in 1996 for regular prominence patrol at Hurbanovo (112 m above sea level).The aim of this collaboration is a joint annual publication of a catalogue of the observed prominences for each year. This paper also describes the form of the catalogue. The authors would appreciate if other observational stations would join this activity. The editor of the catalogue will be the SCO at Hurbanovo.

28

Martinez, P., C. Dorrer, M. Kasper, A. Boccaletti, and K. Dohlen. "Design, analysis, and testing of a microdot apodizer for the apodized pupil Lyot coronagraph." Astronomy and Astrophysics 520 (September 2010): A110. http://dx.doi.org/10.1051/0004-6361/201015351.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

29

Martinez, P., C. Dorrer, E. Aller Carpentier, M. Kasper, A. Boccaletti, K. Dohlen, and N. Yaitskova. "Design, analysis, and testing of a microdot apodizer for the Apodized Pupil Lyot Coronagraph." Astronomy & Astrophysics 495, no. 1 (December 22, 2008): 363–70. http://dx.doi.org/10.1051/0004-6361:200810918.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

30

Martinez, P., C. Dorrer, M. Kasper, A. Boccaletti, and K. Dohlen. "Design, analysis, and testing of a microdot apodizer for the apodized pupil Lyot coronagraph." Astronomy & Astrophysics 500, no. 3 (May 13, 2009): 1281–85. http://dx.doi.org/10.1051/0004-6361/200911824.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

31

Itoh, Satoshi, Taro Matsuo, and Motohide Tamura. "Wide-spectral-band Nuller Insensitive to Finite Stellar Angular Diameter with a One-dimensional Diffraction-limited Coronagraph." Astronomical Journal 167, no. 5 (April 24, 2024): 235. http://dx.doi.org/10.3847/1538-3881/ad3733.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

Abstract Potentially habitable planets around nearby stars less massive than solar-type stars could join targets of the spectroscopy of the planetary reflected light with future space telescopes. However, the orbits of most of these planets occur near the diffraction limit for 6 m diameter telescopes. Thus, while securing contrast-mitigation ability under a broad spectral bandwidth and a finite stellar angular diameter, we must maintain planetary throughput even at the diffraction-limited angles to be able to reduce the effect of the photon noise within a reasonable observation time. A one-dimensional diffraction-limited coronagraph (1DDLC) observes planets near the diffraction limit with undistorted point spread functions but has a finite-stellar diameter problem in wideband use. This study presents a method for wide-spectral-band nulling insensitive to stellar-angular-diameter by adding a fiber nulling with a Lyot-plane phase mask to the 1DDLC. Designing the pattern of the Lyot-plane mask function focuses on the parity of the amplitude spread function of light. Our numerical simulation shows that the planetary throughput (including the fiber-coupling efficiency) can reach about 11% for about 1.35-λ/D planetary separation almost independently of the spectral bandwidth. The simulation also shows the raw contrast of about 4 × 10−8 (the spectral bandwidth of 25%) and 5 × 10−10 (the spectral bandwidth of 10%) for 3 × 10−2 λ/D stellar angular diameter. The planetary throughput depends on the planetary azimuthal angle, which may degrade the exploration efficiency compared to an isotropic throughput but is partially offset the wide spectral band.

32

Crepp, Justin R., Jian Ge, Andrew D. Vanden Heuvel, Shane P. Miller, and Marc J. Kuchner. "Laboratory Testing of a Lyot Coronagraph Equipped with an Eighth‐Order Notch Filter Image Mask." Astrophysical Journal 646, no. 2 (August 2006): 1252–59. http://dx.doi.org/10.1086/504977.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

33

Laginja, Iva, Jean-François Sauvage, Laurent M. Mugnier, Laurent Pueyo, Marshall D. Perrin, James Noss, Scott D. Will, et al. "Wavefront tolerances of space-based segmented telescopes at very high contrast: Experimental validation." Astronomy & Astrophysics 658 (February 2022): A84. http://dx.doi.org/10.1051/0004-6361/202142150.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

Context. The detection and characterization of Earth-like exoplanets (exoEarths) from space requires exquisite wavefront stability at contrast levels of 10−10. On segmented telescopes in particular, aberrations induced by co-phasing errors lead to a light leakage through the coronagraph, deteriorating the imaging performance. These need to be limited in order to facilitate the direct imaging of exoEarths. Aims. We perform a laboratory validation of an analytical tolerancing model that allows us to determine wavefront error requirements in the 10−6 − 10−8 contrast regime for a segmented pupil with a classical Lyot coronagraph. We intend to compare the results to simulations, and we aim to establish an error budget for the segmented mirror on the High-contrast imager for Complex Aperture Telescopes (HiCAT) testbed. Methods. We use the Pair-based Analytical model for Segmented Telescope Imaging from Space to measure a contrast influence matrix of a real high-contrast instrument, and use an analytical model inversion to calculate per-segment wavefront error tolerances. We validate these tolerances on the HiCAT testbed by measuring the contrast response of segmented mirror states that follow these requirements. Results. The experimental optical influence matrix is successfully measured on the HiCAT testbed, and we derive individual segment tolerances from it that correctly yield the targeted contrast levels. Further, the analytical expressions that predict a contrast mean and variance from a given segment covariance matrix are confirmed experimentally.

34

Shestov, S. V., A. N. Zhukov, and D. B. Seaton. "Modeling and removal of optical ghosts in the PROBA-3/ASPIICS externally occulted solar coronagraph." Astronomy & Astrophysics 622 (February 2019): A101. http://dx.doi.org/10.1051/0004-6361/201834584.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

Context. ASPIICS is a novel externally occulted solar coronagraph, which will be launched onboard the PROBA-3 mission of the European Space Agency. The external occulter will be placed on the first satellite ∼150 m ahead of the second satellite that will carry an optical instrument. For 6 h per orbit, the satellites will fly in a precise formation, constituting a giant externally occulted coronagraph. The large distance between the external occulter and the primary objective will allow observations of the white-light solar corona starting from extremely low heights ∼1.1 R⊙. Aims. We aim to analyze the possible influence of optical ghost images formed inside the telescope and to develop an algorithm for their removal. Methods. We implement the optical layout of ASPIICS in Zemax and study the ghost behavior in sequential and nonsequential regimes. We identify sources of the ghost contributions and analyze their geometrical behavior. Finally we develop a mathematical model and software to calculate ghost images for any given input image. Results. We show that ghost light can be important in the outer part of the field of view, where the coronal signal is weak, since the energy of bright inner corona is redistributed to the outer corona. However, the model allows for the ghost contribution to be removed. Due to the large distance between the external occulter and the primary objective, the primary objective does not produce a significant ghost. The use of the Lyot spot in ASPIICS is not necessary.

35

Thomas, Sandrine J., Rémi Soummer, Daren Dillon, Bruce Macintosh, Donald Gavel, and Anand Sivaramakrishnan. "TESTING THE APODIZED PUPIL LYOT CORONAGRAPH ON THE LABORATORY FOR ADAPTIVE OPTICS EXTREME ADAPTIVE OPTICS TESTBED." Astronomical Journal 142, no. 4 (September 12, 2011): 119. http://dx.doi.org/10.1088/0004-6256/142/4/119.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

36

Pourcelot, R., A. Vigan, K. Dohlen, B. Rouzé, J. F. Sauvage, M. El Morsy, M. Lopez, et al. "Calibration of residual aberrations in exoplanet imagers with large numbers of degrees of freedom." Astronomy & Astrophysics 649 (May 2021): A170. http://dx.doi.org/10.1051/0004-6361/202040157.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

Imaging faint objects, such as exoplanets or disks, around nearby stars is extremely challenging because host star images are dominated by the telescope diffraction pattern. Using a coronagraph is an efficient solution for removing diffraction but requires an incoming wavefront with good quality to maximize starlight rejection. On the ground, the most advanced exoplanet imagers use extreme adaptive optics (ExAO) systems that are based on a deformable mirror (DM) with a large number of actuators to efficiently compensate for high-order aberrations and provide diffraction-limited images. While several exoplanet imagers with DMs using ∼1500 actuators are now routinely operating on large telescopes to observe gas giant planets, future systems may require a tenfold increase in the number of degrees of freedom to look for rocky planets. In this paper, we explore wavefront correction with a secondary adaptive optics system that controls a very large number of degrees of freedom that are not corrected by the primary ExAO system. Using Marseille Imaging Testbed for High Contrast (MITHiC), we implement a second stage of adaptive optics with ZELDA, a Zernike wavefront sensor, and a spatial light modulator to compensate for the phase aberrations of the bench downstream residual aberrations from adaptive optics. We demonstrate that their correction up to 137 cycles per pupil with nanometric accuracy is possible, provided there is a simple distortion calibration of the pupil and a moderate wavefront low-pass filtering. We also use ZELDA for a fast compensation of ExAO residuals, showing its promising implementation as a second-stage correction for the observation of rocky planets around nearby stars. Finally, we present images with a classical Lyot coronagraph on MITHiC and validate our ability to reach its theoretical performance with our calibration.

37

Bos, S. P. "The polarization-encoded self-coherent camera." Astronomy & Astrophysics 646 (February 2021): A177. http://dx.doi.org/10.1051/0004-6361/202039569.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

Context. The exploration of circumstellar environments by means of direct imaging to search for Earth-like exoplanets is one of the challenges of modern astronomy. One of the current limitations are evolving non-common path aberrations (NCPA) that originate from optics downstream of the main wavefront sensor. Measuring these NCPA with the science camera during observations is the preferred solution for minimizing the non-common path and maximizing the science duty cycle. The self-coherent camera (SCC) is an integrated coronagraph and focal-plane wavefront sensor that generates wavefront information-encoding Fizeau fringes in the focal plane by adding a reference hole (RH) in the Lyot stop. However, the RH is located at least 1.5 pupil diameters away from the pupil center, which requires the system to have large optic sizes and results in low photon fluxes in the RH. Aims. Here, we aim to show that by featuring a polarizer in the RH and adding a polarizing beamsplitter downstream of the Lyot stop, the RH can be placed right next to the pupil. This greatly increases the photon flux in the RH and relaxes the requirements on the optics size due to a smaller beam footprint. We refer to this new variant of the SCC as the polarization-encoded self-coherent camera (PESCC). Methods. We study the performance of the PESCC analytically and numerically, and compare it, where relevant, to the SCC. We look into the specific noise sources that are relevant for the PESCC and quantify their effect on wavefront sensing and control (WFSC). Results. We show analytically that the PESCC relaxes the requirements on the focal-plane sampling and spectral resolution with respect to the SCC by a factor of 2 and 3.5, respectively. Furthermore, we find via our numerical simulations that the PESCC has effectively access to ∼16 times more photons, which improves the sensitivity of the wavefront sensing by a factor of ∼4. We identify the need for the parameters related to the instrumental polarization and differential aberrations between the beams to be tightly controlled – otherwise, they limit the instrument’s performance. We also show that without additional measurements, the RH point-spread function (PSF) can be calibrated using PESCC images, enabling coherent differential imaging (CDI) as a contrast-enhancing post-processing technique for every observation. In idealized simulations (clear aperture, charge two vortex coronagraph, perfect DM, no noise sources other than phase and amplitude aberrations) and in circumstances similar to those of space-based systems, we show that WFSC combined with CDI can achieve a 1σ raw contrast of ∼3 × 10−11 − 8 × 10−11 between 1 and 18 λ/D. Conclusions. The PESCC is a powerful, new focal-plane wavefront sensor that can be relatively easily integrated into existing ground-based and future space-based high-contrast imaging instruments.

38

Seo, Byoung-Joon, Brian Gordon, Brian Kern, Andy Kuhnert, Dwight Moody, Richard Muller, Ilya Poberezhskiy, John Trauger, and Daniel Wilson. "Hybrid Lyot coronagraph for wide-field infrared survey telescope-astrophysics focused telescope assets: occulter fabrication and high contrast narrowband testbed demonstration." Journal of Astronomical Telescopes, Instruments, and Systems 2, no. 1 (March 8, 2016): 011019. http://dx.doi.org/10.1117/1.jatis.2.1.011019.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

39

Guseva, S. A., and A. D. Shramko. "Study of the Green Coronal Line with Altitude from Out-of-Eclipse Observations during Solar Cycle 24." Космические исследования 61, no. 2 (March 1, 2023): 124–33. http://dx.doi.org/10.31857/s0023420622600180.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

The results of studies of the coronal emission line λ = 5303 Å (Fe XIV) for the period of solar cycle 24 are presented. The spectral data were obtained with an out-of-eclipse Lyot coronagraph at the Mountain Astronomical Station of the Pulkovo Observatory, Russian Academy of Sciences (near Kislovodsk). As a result of processing of out-of-eclipse observations, a database of three types of daily coronal maps of green line intensity I5303 was created with a height distribution h from 1R☉ to 1.38R☉ (R☉ is the radius of the Sun). Irregularities along the λ = 5303 Å line were found and identified, which were associated with the configuration of magnetic fields in the solar corona above active regions. The length of the green line from the position angle of the Sun was calculated. We have shown that the time distribution of the line length in the polar regions has two maxima, which coincide with the times of the reversal of the polar magnetic field on the Sun. The maximum values of the average length of the coronal line along the entire limb occur in 2012–2014. For different phases (the rise, the period of maximum, the decline, and the minimum solar activity) of this solar cycle and for different regions of solar activity, dependences of the height variations of the I5303 values were plotted and studied. The regression equations for these fitting curves are presented. The variation in I5303 with height for the polar regions is most likely determined by a logarithmic function, and the approximating trend curves for the remaining latitudinal zones are determined by a third-order power function.

40

Haffert, S. Y. "The spectrally modulated self-coherent camera (SM-SCC): Increasing throughput for focal-plane wavefront sensing." Astronomy & Astrophysics 659 (March 2022): A51. http://dx.doi.org/10.1051/0004-6361/202141309.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

Context. The detection and characterization of Earth-like exoplanets is one of the major science drivers for the next generation of telescopes. Direct imaging of the planets will play a major role in observations. Current direct imaging instruments are limited by evolving non-common path aberrations (NCPAs). The NCPAs have to be compensated for by using the science focal-plane image. A promising sensor is the self-coherent camera (SCC). An SCC adds a pinhole to the Lyot stop in the coronagraph to introduce a probe electric field. The pinhole has to be separated by at least 1.5 times the pupil size to separate the NCPA speckles from the probe electric field. However, such a distance lets through very little light, which makes it difficult to use an SCC at high speed or on faint targets. Aims. A spectrally modulated self-coherent camera (SM-SCC) is proposed as a solution to the throughput problem. The SM-SCC uses a pinhole with a spectral filter and a dichroic beam splitter, which creates images with and without the probe electric field. This allows the pinhole to be placed closer to the pupil edge and increases the throughput. Combining the SM-SCC with an integral field unit (IFU) can be used to apply more complex modulation patterns to the pinhole and the Lyot stop. A modulation scheme with at least three spectral channels can be used to change the pinhole to an arbitrary aperture with higher throughput. This adds an additional degree of freedom in the design of the SM-SCC. Methods. The performance of the SM-SCC is investigated analytically and through numerical simulations. Results. Numerical simulations show that the SM-SCC increases the pinhole throughput by a factor of 32, which increases the wavefront sensor sensitivity by a factor of 5.7. The reconstruction quality of the sensor is tested by varying the central wavelength of the spectral channels. A smaller separation between the wavelength channels leads to better results. The SM-SCC reaches a contrast of 1 × 10−9 for bright targets in closed-loop control with the presence of photon noise, phase errors, and amplitude errors. The contrast floor on fainter targets is photon-noise-limited and reaches 1 × 10−7. The SM-SCC with an IFU can handle randomly generated reference field apertures. For bright targets, the SM-SCC-IFU reaches a contrast of 3 × 10−9 in closed-loop control with photon noise, amplitude errors, and phase errors. Conclusions. The SM-SCC is a promising focal-plane wavefront sensor for systems that use multiband observations, either through integral field spectroscopy or dual-band imaging.

41

Galicher, R., E. Huby, P. Baudoz, and O. Dupuis. "A family of phase masks for broadband coronagraphy example of the wrapped vortex phase mask theory and laboratory demonstration." Astronomy & Astrophysics 635 (February 28, 2020): A11. http://dx.doi.org/10.1051/0004-6361/201936971.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

Context. Future instruments need efficient coronagraphs over large spectral ranges to enable broadband imaging or spectral characterization of exoplanets that are 108 times fainter than their star. Several solutions have been proposed. Pupil apodizers can attenuate the star intensity by a factor of 1010 but they only transmit a few percent of the light of the planet. Cascades of phase and/or amplitude masks can both attenuate the starlight and transmit most of the planet light, but the number of optics that require alignment makes this solution impractical for an instrument. Finally, vector phase masks can be used to detect faint sources close to bright stars but they require the use of high-quality circular polarizers and, as in the previous solution, this leads to a complex instrument with numerous optics that require alignment and stabilization. Aims. We propose simple coronagraphs that only need one scalar phase mask and one binary Lyot stop providing high transmission for the planet light (> 50%) and high attenuation of the starlight over a large spectral bandpass (∼30%) and a 360° field-of-view. Methods. From mathematical considerations, we find a family of 2D phase masks optimized for an unobscured pupil. One mask is an azimuthal wrapped vortex phase ramp. We probe its coronagraphic performance using numerical simulations and laboratory tests. Results. From numerical simulations, we predict the wrapped vortex can attenuate the peak of the star image by a factor of 104 over a 29% bandpass and 105 over a 18% bandpass with transmission of more than 50% of the planet flux at ∼4λ/D. We confirm these predictions in the laboratory in visible light between 550 and 870 nm. We also obtain laboratory dark hole images in which exoplanets with fluxes that are 3 × 10−8 times the host star flux could be detected at 3σ. Conclusions. Taking advantage of a new technology for etching continuous 2D functions, a new type of mask can be easily manufactured opening up new possibilities for broadband coronagraphy.

42

Sivaramakrishnan, Anand, and James P. Lloyd. "Spiders in Lyot Coronagraphs." Astrophysical Journal 633, no. 1 (November 2005): 528–33. http://dx.doi.org/10.1086/432903.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

43

Lloyd, James P., and Anand Sivaramakrishnan. "Tip‐Tilt Error in Lyot Coronagraphs." Astrophysical Journal 621, no. 2 (March 10, 2005): 1153–58. http://dx.doi.org/10.1086/427719.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

44

Ferrari, Andre. "Analytical Analysis of Lyot Coronagraphs Response." Astrophysical Journal 657, no. 2 (March 10, 2007): 1201–9. http://dx.doi.org/10.1086/511026.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

45

Sivaramakrishnan, Anand, Rémi Soummer, Laurent Pueyo, J. Kent Wallace, and Michael Shao. "Sensing Phase Aberrations behind Lyot Coronagraphs." Astrophysical Journal 688, no. 1 (November 20, 2008): 701–8. http://dx.doi.org/10.1086/591957.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

46

Oppenheimer, B. R., R. G. Dekany, M. Troy, T. Hayward, and B. Brandl. "Companion Detection Limits with Adaptive Optics Coronagraphy." Symposium - International Astronomical Union 202 (2004): 99–102. http://dx.doi.org/10.1017/s0074180900217592.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

We present a study of the Palomar Adaptive Optics System and the PHARO near infrared camera in coronagraphic mode. The camera provides two different focal plane occulting masks–opaque circular disks 0.43 and 0.97″ across. Three different pupil plane apodizing masks (Lyot masks) are also provided. The six different combinations of Lyot mask and focal plane mask suppress differently the point spread function of a bright star centered on the focal plane mask. We obtained images of the bright nearby star Gliese 614 with all six different configurations in the K filter. We measured the dynamic range achievable with these configurations. Within 2.5″, the dynamic range is at least 8 magnitudes at the 5σ level and as high as 12 in a 1 s exposure. This represents a substantial gain over similar techniques without adaptive optics.

47

Sivaramakrishnan, Anand, and Natalia Yaitskova. "Lyot Coronagraphy on Giant Segmented-Mirror Telescopes." Astrophysical Journal 626, no. 1 (May 19, 2005): L65—L68. http://dx.doi.org/10.1086/431460.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

48

Aime, C., and R. Soummer. "Cascading properties of Prolate Apodized Lyot Coronagraphs." EAS Publications Series 12 (2004): 281–86. http://dx.doi.org/10.1051/eas:2004041.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

49

Soummer, Rémi. "Apodized Pupil Lyot Coronagraphs for Arbitrary Telescope Apertures." Astrophysical Journal 618, no. 2 (December 15, 2004): L161—L164. http://dx.doi.org/10.1086/427923.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

50

Yaitskova, N. "Peculiarity of Lyot Coronagraphy for Highly Segmented Apertures." EAS Publications Series 22 (2006): 223–37. http://dx.doi.org/10.1051/eas:2006135.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.