Bright Objects Research Articles

STARRED: a two-channel deconvolution method with Starlet regularization

The spatial resolution of astronomical images is limited by atmospheric turbulence and diffraction in the telescope optics, resulting in blurred images. This makes it difficult to accurately measure the brightness of blended objects because the contributions from adjacent objects are mixed in a time-variable manner due to changes in the atmospheric conditions. However, this effect can be corrected by characterizing the Point Spread Function (PSF), which describes how a point source is blurred on a detector. This function can be estimated from the stars in the field of view, which provides a natural sampling of the PSF across the entire field of view. Once the PSF is estimated, it can be removed from the data through the so-called deconvolution process, leading to images of improved spatial resolution. The deconvolution operation is an ill-posed inverse problem due to noise and pixelization of the data. To solve this problem, regularization is necessary to guarantee the robustness of the solution. Regularization can take the form of a sparse prior, meaning that the recovered solution can be represented with only a few basis eigenvectors. STARRED is a Python package developed in the context of the COSMOGRAIL collaboration and applies to a vast variety of astronomical problems. It proposes to use an isotropic wavelet basis, called Starlets, to regularize the solution of the deconvolution problem. This family of wavelets has been shown to be well-suited to represent astronomical objects. STARRED provides two modules to first reconstruct the PSF, and then perform the deconvolution. It is based on two key concepts: i) the image is reconstructed in two separate channels, one for the point sources and one for the extended sources, and ii) the code relies on the deliberate choice of not completely removing the effect of the PSF, but rather bringing the image to a higher resolution.

Optimal attitude maneuvers in the presence of prohibited directions

AbstractWe consider the problem of realigning a space telescope from one observation target to the next in the presence of prohibited directions. More specifically, we want to steer the space telescope – modelled as a gyrostat – from an initial attitude at rest to a final attitude at rest within a fixed time interval. During the motion, the line of sight of the telescope must be kept away from forbidden directions towards bright objects like the sun, moon or earth due to power or thermal requirements. The kinematics of the spacecraft motion are governed by a differential equation on the rotation group SO(3). Treating the angular velocities as control variables, this equation takes the form of a controlled dynamical system. To ensure reorientation maneuvers satisfying these pointing constraints, we introduce a cost functional penalizing proximity of the line of sight of the telescope to any of the forbidden directions. Furthermore, we include penalty terms which provide a smooth motion of the satellite and ensure the execution of a rest‐to‐rest maneuver. The chosen cost functional is minimized over all possible trajectories of the controlled dynamical system between the prescribed initial and target attitudes, which leads to an optimal control problem on SO(3), which is solved by applying a version of Pontryagin's Maximum Principle tailor‐made for optimal control problems on Lie groups. Parametrizing SO(3) in terms of Cardan angles, the solution is formulated as a boundary‐value problem on Euclidean space and hence can be solved numerically by conventional methods. The existence of two first integrals is established and exploited to reduce the computational effort. The applicability of this approach is shown in concrete examples.

A Young White Dwarf Orbiting PSR J1835−3259B in the Bulge Globular Cluster NGC 6652

We report on the discovery of the companion star to the millisecond pulsar PSR J1835−3259B in the Galactic globular cluster NGC 6652. Taking advantage of deep photometric archival observations acquired through the Hubble Space Telescope in near-UV and optical bands, we identified a bright and blue object at a position compatible with that of the radio pulsar. The companion is located along the helium-core white dwarf cooling sequence, and the comparison with binary evolution models provides a mass of 0.17 ± 0.02 M ⊙, a surface temperature of 11,500 ± 1900 K, and a very young cooling age of only 200 ± 100 Myr. The mass and the age of the companion are compatible with a progenitor star of about 0.87 M ⊙, which started transferring mass to the primary during its evolution along the subgiant branch and stopped during the early red giant branch phase. Combining together the pulsar mass function and the companion mass, we found that this system is observed at an almost edge-on orbit and hosts a neutron star with a mass of 1.44 ± 0.06 M ⊙, thus suggesting a highly nonconservative mass accretion phase. The young age of the WD companion is consistent with the scenario of a powerful, relatively young MSP indicated by the earlier detection of gamma-rays from this system.

The Peculiar Variable X-Ray Spectrum of the Active Galactic Nucleus PKS 2005–489

PKS 2005−489 is a well-known, bright southern BL Lac object that has been detected up to TeV energies. In a low-flux state it exhibits the expected multiwavelength double-peaked spectrum in the radio−γ-ray band. The high-flux state shows extreme flux variations in the X-ray band with a hardening as well as a peculiar curved feature in the spectrum. Thus far, PKS 2005−489 is the only source to exhibit such a feature. To study the X-ray variability further, we obtained the first hard X-ray spectrum of the source with the Nuclear Spectroscopic Telescope Array. We compare quasi-simultaneous radio, optical, UV, soft and hard X-ray, and γ-ray data of PKS 2005−489 to archival data in order to study its broadband behavior. We find a very consistent quiet state in the spectral energy distribution, with little variation in spectral shape or flux between the 2012 and 2020 data. A possible explanation for the peculiar X-ray spectrum in the flaring state is an additional component in the jet, possibly accelerated via magnetic reconnection, that is not co-spatial to the low-flux state emission region.

Identifying Lesions of the Corpus Callosum in Patients with Neurofibromatosis Type I (P8-13.004)

<h3>Objective:</h3> To investigate the rate of lesions of the corpus callosum, including both unidentified bright objects (UBOs) and gliomas, in a large cohort of NF1 patients. <h3>Background:</h3> Neurofibromatosis type I is an autosomal dominant disorder with a multisystem presentation. Patients with NF1 are frequently found to have intracranial lesions, including areas of increased T2 signal intensity known as UBOs, as well as tumors known as gliomas. The presence of these lesions in the corpus callosum has not been studied in a large cohort. <h3>Design/Methods:</h3> We reviewed the medical records of 1373 patients (aged 3 months to 86 years) with NF1 followed at our institution over 2012–2021. Patients with UBOs or gliomas found on MRI in the corpus callosum were identified and recorded. <h3>Results:</h3> Of the 1373 patients analyzed, 34 were reported to have UBOs in the corpus callosum. This represents 6.3% of the 538 patients with any UBO. The majority of corpus callosum UBOs were in the splenium (41%), followed by the body (18%), and genu (12%). Nine patients were reported with corpus callosum gliomas, representing 5.6% of the 161 patients with any glioma. Of these, 7 (78%) were in the splenium. Over the course of follow-up imaging, 5/7 remained stable, 2/7 decreased in size and then stabilized, and 1/7 increased in size. <h3>Conclusions:</h3> Our study indicates a 2.5% and 0.7% prevalence of corpus callosum UBOs and gliomas, respectively. The majority of lesions are present in the splenium, and frequently remain stable over time. This adds to growing data regarding imaging findings in NF1 patients to better inform appropriate follow-up. <b>Disclosure:</b> Ms. Jandhyala has nothing to disclose. Dr. Garcia has nothing to disclose. Miss Kim has nothing to disclose. Dr. Segal has nothing to disclose. Dr. Yohay has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Astra Zeneca. Dr. Yohay has received publishing royalties from a publication relating to health care. An immediate family member of Dr. Yohay has received publishing royalties from a publication relating to health care.

Video Spectral Methods and Tools for Monitoring of Controlled Parameters of Forest Fires and Oil Spill Accidents

The main results of the creation of the domestic complex “Vizir” for measuring bidirectional spectropolarization reflection coefficients and brightness of natural and artificial objects were presented in the article. Its purpose, composition and main technical parameters were indicated.Spectral-polarization studies of the characteristics of samples that simulates objects (pollution) of natural (forest fires) and man-made (oil spills) emergencies were performed with the help of complex “Vizir” using polarizing nozzles under various conditions (angles of illumination, observation, pollution concentration, the time that passed since the contamination, the degree of wood thermal damage). The results of studies made it possible to increase the accuracy of identification of monitoring objects in emergency zones up to two times.The main provisions of the two developed methods were outlined. The first method was methodology for determination of the controlled parameters of forest fires by means of aviation monitoring, which makes it possible to record the maximum values of the degree of polarization of reflected radiation for coal 30–40 % and for semi-coal 15–20 % in the wavelength range from 0.5 to 0.7 μm. The second one was methodology for determination of the controlled parameters of man-made emergencies with oil spills by means of aviation monitoring, which makes it possible to record the maximum values of the degree of polarization of an oil spill on water: 40–50 % at optimal view angles close to specular in relation to the angle of solar radiation incidence.The developed methods were introduced into the activities of the Ministry for Emergency Situations of the Republic of Belarus to make the right management decisions to eliminate emergency situations and their consequences.

Discovery of the luminous X-ray ignition eRASSt J234402.9−352640

In November 2020, a new, bright object, eRASSt J234402.9−352640, was discovered in the second all-sky survey of SRG/eROSITA. The object brightened by a factor of at least 150 in 0.2–2.0 keV flux compared to an upper limit found six months previous, reaching an observed peak of 1.76−0.24+0.03 × 10−11 erg cm−2 s−1. The X-ray ignition is associated with a galaxy at z = 0.10, making the peak luminosity log10(L0.2−2 keV/[erg s−1]) = 44.7 ± 0.1. Around the time of the rise in X-ray flux, the nucleus of the galaxy brightened by approximately 3 mag. in optical photometry, after correcting for the host contribution. We present X-ray follow-up data from Swift, XMM-Newton, and NICER, which reveal a very soft spectrum as well as strong 0.2–2.0 keV flux variability on multiple timescales. Optical spectra taken in the weeks after the ignition event show a blue continuum with broad, asymmetric Balmer emission lines, and high-ionisation ([OIII]λλ4959,5007) and low-ionisation ([NII]λ6585, [SII]λλ6716,6731) narrow emission lines. Following the peak in the optical light curve, the X-ray, UV, and optical photometry all show a rapid decline. The X-ray light curve shows a decrease in luminosity of ∼0.45 over 33 days and the UV shows a drop of ∼0.35 over the same period. eRASSt J234402.9−352640 also shows a brightening in the mid-infrared, likely powered by a dust echo of the luminous ignition. We find no evidence in Fermi-LAT γ-ray data for jet-like emission. The event displays characteristics of a tidal disruption event (TDE) as well as of an active galactic nucleus (AGN), complicating the classification of this transient. Based on the softness of the X-ray spectrum, the presence of high-ionisation optical emission lines, and the likely infrared echo, we find that a TDE within a turned-off AGN best matches our observations.

JWST high-redshift galaxy constraints on warm and cold dark matter models

Context. Warm dark matter is a possible alternative to cold dark matter to explain cosmological structure formation. Aims. We study the implications of the latest JWST data on the nature of dark matter. Methods. We compare properties of high-redshift galaxies observed by JWST with hydrodynamical simulations, in the standard cold dark matter model and in warm dark matter models with a suppressed linear matter power spectrum Results. We find that current data are neither in tension with cold dark matter nor with warm dark matter models with mWDM &gt; 2 keV, since they probe bright and rare objects whose physical properties are similar in the different scenarios. Conclusions. We also show how two observables, the galaxy luminosity functions and the galaxy correlation function at small scales of faint objects, can be promising tools for discriminating between the different dark-matter scenarios. Further hints may come from early stellar-mass statistics and galaxy CO emission.

Algebraic Methods for Achieving Super-Resolution by Digital Antenna Arrays

The actual modern problem of developing and improving measurement and observation systems (including robotic ones) is to increase the volume and quality of the information received. Increasing the angle resolution to values significantly exceeding the Rayleigh criterion, i.e. achieving super-resolution is one of important ways to solve the problem. Angular super-resolution which makes it possible to detail images of research objects and their individual fragments, improves the quality of solutions to detection, recognition and identification problems, increases the range of such systems. In many papers methods developed by authors to achieve a super-resolution based on approximate solutions of inverse problems in the form of Fredholm integral equation of the first kind of convolution type called algebraic are presented. The methods used, as well as their varieties, make it possible to reduce solutions of inverse problems posed to solving sets of linear algebraic equations (SLAE). This paper presents results of further improvement of algebraic methods based on intelligent analysis of received signals. It is shown that their use in systems based on digital antenna arrays makes it possible to increase the achieved degree of exceeding the Rayleigh criterion. In the course of numerical experiments with a mathematical model, the stability of the solutions obtained and their adequacy were confirmed. The numerical results obtained open the following possibilities: (1) obtaining images of studied objects with a resolution exceeding the Rayleigh criterion by 4 to 10 times, (2) determining the angular coordinates of individual small-sized objects as part of multi-element complex objects (group targets), (3) clarifying boundaries of extended objects and their individual elements, (4) localizing individual bright objects on a smoothly inhomogeneous reflective background. Applying presented new methods does not require a significant computing power, what allows you to work in a real time mode using relatively simple and inexpensive computing devices. The ways of further improvement of presented algebraic methods for solving applied inverse problems are described.

Universality in the random walk structure function of luminous quasi-stellar objects

Rapidly growing black holes are surrounded by accretion disks that make them the brightest objects in the Universe. Their brightness is known to be variable, but the causes of this are not implied by simple disk models and still debated. Due to the small size of accretion disks and their great distance, there are no resolved images addressing the puzzle. In this work, we study the dependence of their variability on luminosity, wavelength and orbital/thermal timescale. We use over 5,000 of the most luminous such objects with light curves of almost nightly cadence from >5 years of observations by the NASA/ATLAS project, which provides 2 billion magnitude pairs for a structure function analysis. When time is expressed in units of orbital or thermal timescale in thin-disk models, we find a universal structure function, independent of luminosity and wavelength, supporting the model of magneto-rotational instabilities as a main cause. Over a >1 dex range in time, the fractional variability amplitude follows $$\log (A/{A}_{0})\simeq 1/2\times \log (\Delta t/{t}_{{{{\rm{th}}}}})$$ . Deviations from the universality may hold clues as to the structure and orientation of disks. A study of the emission variability of roughly 5,000 of the brightest quasars supports the presence of an optically thick yet geometrically thin accretion disk, and may provide a means of measuring the size and inclination of the disk.

Sky subtraction in an era of low surface brightness astronomy

ABSTRACT The Vera C. Rubin Observatory Wide-Fast Deep sky survey will reach unprecedented surface brightness depths over tens of thousands of square degrees. Surface brightness photometry has traditionally been a challenge. Current algorithms which combine object detection with sky estimation systematically oversubtract the sky, biasing surface brightness measurements at the faint end and destroying or severely compromising low surface brightness light. While it has recently been shown that properly accounting for undetected faint galaxies and the wings of brighter objects can in principle recover a more accurate sky estimate, this has not yet been demonstrated in practice. Obtaining a consistent spatially smooth underlying sky estimate is particularly challenging in the presence of representative distributions of bright and faint objects. In this paper, we use simulations of crowded and uncrowded fields designed to mimic Hyper Suprime-Cam data to perform a series of tests on the accuracy of the recovered sky. Dependence on field density, galaxy type, and limiting flux for detection are all considered. Several photometry packages are utilized: source extractor, gnuastro, and the LSST science pipelines. Each is configured in various modes, and their performance at extreme low surface brightness analysed. We find that the combination of the source extractor software package with novel source model masking techniques consistently produce extremely faint output sky estimates, by up to an order of magnitude, as well as returning high fidelity output science catalogues.

Single image dehazing via color balancing and quad-decomposition atmospheric light estimation

In recent years, single image dehazing methods have achieved good performance. But there still exists some problems, such as color distortion, excessive smoothing of image texture details and image over-saturation. For solving these problems, this paper proposes an improved single image dehazing algorithm based on Color Balancing and Quad-Decomposition (CBQD). In the pre-processing stage, we define an indicator for detecting image unbalance color channel, and correct color of images that are prone to color distortion in some special environments (e.g., sandstorms). In the dehazing phase of the algorithm, we apply the improved quad-decomposition technique for eliminating the interference of non-atmospheric light source and certain bright objects, thus can estimate atmospheric light accurately. Meanwhile, we obtain the image depth information by the linear model and estimate the initial image transmission map by fused depth map, and then refine the transmission map using a gradient domain-guided filter with edge-preserving characteristics. Finally, we can restore the scene radiance, and the dehazed images have clear edges, rich texture, no halo artifacts, and natural color. Extensive experiments verifies the superiority of CBQD over state-of-the-art image dehazing techniques in terms of both the recovery quality and efficiency.

Study on the enhancement method of online monitoring image of dense fog environment with power lines in smart city.

In this research, an image defogging algorithm is proposed for the electricity transmission line monitoring system in the smart city. The electricity transmission line image is typically situated in the top part of the image which is rather thin in size. Because the electricity transmission line is situated outside, there is frequently a sizable amount of sky in the backdrop. Firstly, an optimized quadtree segmentation method for calculating global atmospheric light is proposed, which gives higher weight to the upper part of the image with the sky region. This prevents interference from bright objects on the ground and guarantees that the global atmospheric light is computed in the top section of the image with the sky region. Secondly, a method of transmission calculation based on dark pixels is introduced. Finally, a detail sharpening post-processing based on visibility level and air light level is introduced to enhance the detail level of electricity transmission lines in the defogging image. Experimental results indicate that the algorithm performs well in enhancing the image details, preventing image distortion and avoiding image oversaturation.

Using a semi-automated approach to quantify Unidentified Bright Objects in Neurofibromatosis type 1 and linkages to cognitive and academic outcomes

Neurofibromatosis type 1 (NF1) is an autosomal dominant neurocutaneous syndrome that affects multiple organ systems resulting in widespread symptoms, including cognitive deficits. In addition to the criteria required for an NF1 diagnosis, approximately 70% of children with NF1 present with Unidentified Bright Objects (UBOs) or Focal Areas of Signal Intensity, which are hyperintense bright spots seen on T2-weighted magnetic resonance images and seen more prominently on FLAIR magnetic resonance images (Sabol et al., 2011). Current findings relating the presence/absence, quantities, sizes, and locations of these bright spots to cognitive abilities are mixed. To contribute to and hopefully disentangle some of these mixed findings, we explored potential relationships between metrics related to UBOs and cognitive abilities in a sample of 28 children and adolescents with NF1 (M=12.52 years; SD=3.18 years; 16 male). We used the Lesion Segmentation Tool (LST) to automatically detect and segment the UBOs. The LST was able to qualitatively and quantitatively reliably detect UBOs in images of children with NF1. Using these automatically detected and segmented lesions, we found that while controlling for age, biological sex, perceptual IQ, study, and scanner, “total UBO volume”, defined as the sum of all the voxels representing all of the UBOs for each participant, helped explain differences in word reading, phonological awareness, and visuospatial skills. These findings contribute to the emerging NF1 literature and help parse the specific deficits that children with NF1 have, to then help improve the efficacy of reading interventions for children with NF1.

The General Relativistic Perspective

Schwarzschild objects are not black holes. They are the brightest objects in the universe. Classical Relativity equations are simplistic as they only use values observed from an undistorted viewpoint. The general relativity distortion slows gravitons, reducing the force they exert. Hence, distortion limits escape velocity to c, similar to special relativity. The slow atomic structure of bosons and elements decays rapidly, and their energy increases the matter particle’s velocity. The lower the atomic weight, the greater the speed, which matches the EM signature of hydrogen that escapes in the most significant amount. This study shows that the distortion is always mathematically real and never imaginary.

A near-field treatment of aperture synthesis techniques using the Murchison Widefield Array

Abstract Typical radio interferometer observations are performed assuming the source of radiation to be in the far-field of the instrument, resulting in a two-dimensional Fourier relationship between the observed visibilities in the aperture plane and the sky brightness distribution (over a small field of view). When near-field objects are present in an observation, the standard approach applies far-field delays during correlation, resulting in loss of signal coherence for the signal from the near-field object. In this paper, we demonstrate near-field aperture synthesis techniques using a Murchison Widefield Array observation of the International Space Station (ISS), as it appears as a bright near-field object. We perform visibility phase corrections to restore coherence across the array for the near-field object (however not restoring coherence losses due to time and frequency averaging at the correlator). We illustrate the impact of the near-field corrections in the aperture plane and the sky plane. The aperture plane curves to match the curvature of the near-field wavefront, and in the sky plane near-field corrections manifest as fringe rotations at different rates as we bring the focal point of the array from infinity to the desired near-field distance. We also demonstrate the inverse scenario of inferring the line-of-sight range of the ISS by inverting the apparent curvature of the wavefront seen by the aperture. We conclude the paper by briefly discussing the limitations of the methods developed and the near-field science cases where our approach can be exploited.

Spectroscopic Time-series Performance of JWST/NIRSpec from Commissioning Observations

We report on James Webb Space Telescope (JWST) commissioning observations of the transiting exoplanet HAT-P-14 b, obtained using the Bright Object Time Series (BOTS) mode of the NIRSpec instrument with the G395H/F290LP grating/filter combination (3–5 μm). While the data were used primarily to verify that the NIRSpec BOTS mode is working as expected, and to enable it for general scientific use, they yield a precise transmission spectrum which we find is featureless down to the precision level of the instrument, consistent with expectations given HAT-P-14 b’s small scale-height and hence expected atmospheric features. The exquisite quality and stability of the JWST/NIRSpec transit spectrum—almost devoid of any systematic effects—allowed us to obtain median uncertainties of 50–60 ppm in this wavelength range at a resolution of R = 100 in a single exposure, which is in excellent agreement with pre-flight expectations and close to the (or at the) photon-noise limit for a J = 9.094, F-type star like HAT-P-14. These observations showcase the ability of NIRSpec/BOTS to perform cutting-edge transiting exoplanet atmospheric science, setting the stage for observations and discoveries to be made in Cycle 1 and beyond.

The evaluation of anterior thalamic radiation with diffusion tensor imaging in children with neurofibromatosis type-1

To determine whether there is a difference in the apparent diffusion coefficient (ADC) and fractional anisotropy (FA) values of the anterior thalamic radiation (ATR), which are involved in the inhibitory control mechanism, in Neurofibromatosis type-1 (NF1) patients with or without Neurofibromatosis bright objects (NBOs), in comparison to the healthy control group. Thirty children diagnosed with NF1 and 17 age-matched children were included in the study. 30 children with NF1 had a mean age of 10.47±5.43, compared to 11.35±5.43 of the control group. NF1 patients were divided into two groups as those with and without NBOs. The comparison was made by measuring ADC and FA values of ATR in patients with NF1 and a healthy control group. There was a significant difference in terms of ADC and FA values of ATR between the patients with NF1 and the control group. While a significant decrease was seen in FA values of ATR, ADC values were increased. There was a significant difference in ATR ADC and FA values between NF1 patients with and without NBOs and the healthy control group. On the other hand, no major difference was displayed between NF1 patients with NBOs and without NBOs in terms of ATR ADC and FA values. The results of increased ADC and decreased FA values may denote the demyelination process in ATR. We speculate that the onset of microstructural damage in the ATR may result in executive function impairment, particularly in the inhibitory control mechanism.

A Novel Spectral Indices-Driven Spectral-Spatial-Context Attention Network for Automatic Cloud Detection

Cloud detection is a fundamental step for optical satellite image applications. Although existing deep learning method can provide more accurate cloud detection result. However, performance of these methods rely on a large number of label samples, whose collection is time-consuming and high cost. In addition, cloud detection is challenging in high brightness scenes due to due to cloud and high brightness object have a similar spectral feature. In this study, we propose a cloud index driven spectral-spatial-context attention network (SSCA-net) for cloud detection, which relies on no effort to manually collect label samples and can improve the accuracy cloud detection in high brightness scenes. The label samples are automatically generated from cloud index by using dual-threshold, which is then expanded to improve the completeness of cloud mask labels. We designed SSCA-net with the spectral-spatial-context aware module and spectral-spatial-context information aggregation module, aimed to improve the accuracy cloud detection in high brightness scenes. The results show that the proposed SSCA-net achieved good performance with average overall accuracy of 97.69% and average Kappa coefficient of 92.71% on Sentinel-2 and Landsat-8 dataset. This paper provides a fresh insight into how advanced deep attention network and cloud index can be integrated to obtain high accuracy of cloud detection on high brightness scenes.

Robust air-light estimation for a single hazy image using haze-lines in Plüker coordinates.

Image dehazing is a valid way to reduce the negative impacts of bad weather, such as fog and haze, on outdoor optical imaging. The effect of the image dehazing heavily relies on the air-light estimation. Most existing methods exploit the prior information, which is generally obtained by simply assessing the brightest pixels' intensity in a hazy image, to estimate the air-light. However, bright objects, such as lamps, lead to the failure of these methods. So, a novel method for robust and optimal air-light estimation using haze-lines described in Plüker coordinates is proposed. First, the exact analytic solution of the air-light, i.e., the intersection of haze-lines, is derived via analyzing the geometric relationship between haze-lines in three-dimensional RGB space using their Plüker coordinates. Then, a novel air-light estimation algorithm using haze-lines in Plüker coordinates is elaborated. Finally, extensive experiments are performed to validate the proposed algorithm. Experimental results reveal that the proposed algorithm can more robustly and accurately estimate the air-light.