Abstract
In the context of extreme adaptive optics for large telescopes, we present the Kraken multi-frame blind deconvolution (MFBD) algorithm for processing high-cadence acquisitions, capable of ...providing a diffraction-limited estimation of the source brightness distribution. This is achieved by a data modeling of each frame in the sequence driven by the estimation of the instantaneous wave front at the entrance pupil. Under suitable physical constraints, numerical convergence is guaranteed by an iteration scheme starting from a compact MFBD, which provides a very robust initial guess that only employs a few frames. We describe the mathematics behind the process and report the high-resolution reconstruction of the spectroscopic binary
α
And (16.3 mas separation) acquired with the precursor of SHARK-VIS, the upcoming high-contrast camera in the visible for the Large Binocular Telescope.
Since volcanic activity was first discovered on Io from Voyager images in 1979, changes on Io's surface have been monitored from both spacecraft and ground‐based telescopes. Here, we present the ...highest spatial resolution images of Io ever obtained from a ground‐based telescope. These images, acquired by the SHARK‐VIS instrument on the Large Binocular Telescope, show evidence of a major resurfacing event on Io's trailing hemisphere. When compared to the most recent spacecraft images, the SHARK‐VIS images show that a plume deposit from a powerful eruption at Pillan Patera has covered part of the long‐lived Pele plume deposit. Although this type of resurfacing event may be common on Io, few have been detected due to the rarity of spacecraft visits and the previously low spatial resolution available from Earth‐based telescopes. The SHARK‐VIS instrument ushers in a new era of high resolution imaging of Io's surface using adaptive optics at visible wavelengths.
Plain Language Summary
A new instrument, called SHARK‐VIS, on the Large Binocular Telescope in Arizona, has obtained high spatial resolution, visible wavelength images of Io, the highly volcanic moon of Jupiter. Large multicolored plume deposits were imaged, revealing where the red deposit from a volcano named Pele was covered by another plume deposit from another volcano, named Pillan Patera, the site of a powerful eruption in 2021. SHARK‐VIS ushers in a new age in planetary imaging.
Key Points
High resolution images taken with SHARK‐VIS at LBT reveal low and high albedo features obscuring a portion of Pele's red ring on Io
This new eruption deposit likely originated from a powerful eruption in August 2021 located at Pillan Patera
Such images provide a new imaging capability that yields vital context to other observations of planetary surfaces
We present a new processing technique that significantly improves the angular differential imaging method (ADI). Its context of application is that of high-contrast imaging of faint objects nearby ...bright stars in observations obtained with extreme adaptive optics (EXAO) systems. This technique, named "SFADI" for "Speckle-Free ADI," improves the achievable contrast by means of speckles identification and suppression. This is possible in very high cadence data, which freeze the atmospheric evolution. Here we present simulations in which synthetic planets are injected into a real millisecond frame rate sequence, acquired at the LBT telescope at a visible wavelength, and show that this technique can deliver a low and uniform background, allowing for unambiguous detection of 10−5 contrast planets, from 100 to 300 mas separations, under poor and highly variable seeing conditions (0.8 to 1.5 arcsec FWHM) and in only 20 minutes of acquisition. A comparison with a standard ADI approach shows that the contrast limit is improved by a factor of 5. We extensively discuss the SFADI dependence on the various parameters like the speckle identification threshold, frame integration time, and number of frames, as well as its ability to provide high-contrast imaging for extended sources and also to work with fast acquisitions.
We have developed an optimal subtraction algorithm for removing the residuals of the sky background from multi-fiber spectra. In particular, this algorithm is suited to recover the flux of unresolved ...lines blended with atmospheric line features and works well in case of spectra dominated by the sky component. Our method is based on PSF matching and can compensate both imperfect wavelength calibration residuals and fiber-to-fiber PSF variations. Using simulated fiber spectra of an emission line object, we show how the algorithm improves the accuracy in line fluxes evaluation and retrieves diagnostic lines normally hidden, making them usable for scientific analysis.
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