A fast 2D image reconstruction algorithm from 1D data for the Gaia mission

Harrison, D. L.

doi:10.1007/s10686-011-9240-7

Cited by 20 publications

(21 citation statements)

References 6 publications

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“…We have over 30 high-quality candidates left to follow-up that will begin to fill this missing parameter space. Future Gaia data releases will help confirm these lenses efficiently via: more precise proper motion measurements, autocorrelation searches based on Gaia lightcurves, and 2-D PSF reconstruction techniques to search for lensing galaxies directly in the Gaia data (Harrison 2011).…”

Section: Discussionmentioning

confidence: 99%

Gravitationally lensed quasars in Gaia – II. Discovery of 24 lensed quasars

Lemon

Auger

McMahon

et al. 2018

Monthly Notices of the Royal Astronomical Society

102

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We report the discovery and spectroscopic confirmation of 22 new gravitationally lensed quasars found using Gaia data release 2. The selection was made using several techniques: multiple Gaia detections around objects in quasar candidate catalogues, modelling of unWISE coadd pixels using Gaia astrometry, and Gaia detections offset from photometric and spectroscopic galaxies. Spectra of 33 candidates were obtained with the William Herschel Telescope, 22 of which are lensed quasars, 2 highly probably lensed quasars, 5 nearly identical quasar pairs, 1 inconclusive system, and 3 contaminants. Of the 3 confirmed quadruply imaged systems, J2145+6345 is a 2.1 arcsecond separation quad with 4 bright images (G=16. 86, 17.26, 18.34, 18.56), making it ideal for time delay monitoring. Analysing this new sample alongside known lenses in the Pan-STARRS footprint, and comparing to expected numbers of lenses, we show that, as expected, we are biased towards systems with bright lensing galaxies and low source redshifts. We discuss possible techniques to remove this bias from future searches. A |b|>20 complete sample of lensed quasars detected by Gaia and with image separations above 1 arcsecond will provide a valuable statistical sample of around 350 systems. Currently only 96 known lenses satisfy these criteria, yet promisingly, our unWISE modelling technique is able to recover all of these with simple WISE-Gaia colour cuts that remove ∼80 per cent of previously followed-up contaminants. Finally, we provide an online database of known lenses, quasar pairs, and contaminant systems.

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Section: Discussionmentioning

confidence: 99%

Gravitationally lensed quasars in Gaia – II. Discovery of 24 lensed quasars

Lemon

Auger

McMahon

et al. 2018

Monthly Notices of the Royal Astronomical Society

102

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“…Source environment analysis (SEA). This task (Harrison 2011) performs a combined analysis of all the SM and AF images collected over the mission lifetime for a given source. A stacking of the images allows a slightly deeper survey of the surroundings of each source and in particular enables the identification of neighbouring sources that are not visible in the individual images.…”

Section: Cyclic Data Processingmentioning

confidence: 99%

TheGaiamission

Prusti¹,

Bruijne²,

Brown³

et al. 2016

A&A

5,370

1,139

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Gaia is a cornerstone mission in the science programme of the European Space Agency (ESA). The spacecraft construction was approved in 2006, following a study in which the original interferometric concept was changed to a direct-imaging approach. Both the spacecraft and the payload were built by European industry. The involvement of the scientific community focusses on data processing for which the international Gaia Data Processing and Analysis Consortium (DPAC) was selected in 2007. Gaia was launched on 19 December 2013 and arrived at its operating point, the second Lagrange point of the Sun-Earth-Moon system, a few weeks later. The commissioning of the spacecraft and payload was completed on 19 July 2014. The nominal five-year mission started with four weeks of special, ecliptic-pole scanning and subsequently transferred into full-sky scanning mode. We recall the scientific goals of Gaia and give a description of the as-built spacecraft that is currently (mid-2016) being operated to achieve these goals. We pay special attention to the payload module, the performance of which is closely related to the scientific performance of the mission. We provide a summary of the commissioning activities and findings, followed by a description of the routine operational mode. We summarise scientific performance estimates on the basis of in-orbit operations. Several intermediate Gaia data releases are planned and the data can be retrieved from the Gaia Archive, which is available through the Gaia home page.

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“…By the final Gaia data release, the astrometry will be substantially more precise: on-ground processing may allow identification of stellar pairs with separations as small as 0.1 (Harrison 2011), and proper motions may reach a precision of ≈0.25 mas yr −1 . Using these limits, we generate the rectangular areas in the bottom panel of Figure 1.…”

Section: Challengesmentioning

confidence: 99%

Wide binaries in Tycho-Gaia: search method and the distribution of orbital separations

Andrews

Chanamé

Agüeros

2017

Monthly Notices of the Royal Astronomical Society

112

136

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We mine the Tycho-Gaia astrometric solution (TGAS) catalog for wide stellar binaries by matching positions, proper motions, and astrometric parallaxes. We separate genuine binaries from unassociated stellar pairs through a Bayesian formulation that includes correlated uncertainties in the proper motions and parallaxes. Rather than relying on assumptions about the structure of the Galaxy, we calculate Bayesian priors and likelihoods based on the nature of Keplerian orbits and the TGAS catalog itself. We calibrate our method using radial velocity measurements and obtain 6196 highconfidence candidate wide binaries with projected separations s 1 pc. The normalization of this distribution suggests that at least 0.6% of TGAS stars have an associated, distant TGAS companion in a wide binary. We demonstrate that Gaia's astrometry is precise enough that it can detect projected orbital velocities in wide binaries with orbital periods as large as 10 6 yr. For pairs with s < ∼ 4 × 10 4 AU, characterization of random alignments indicate our contamination to be ≈5%. For s 5 × 10 3 AU, our distribution is consistent withÖpik's Law. At larger separations, the distribution is steeper and consistent with a power-law P(s) ∝ s −1.6 ; there is no evidence in our data of any bimodality in this distribution for s 1 pc. Using radial velocities, we demonstrate that at large separations, i.e., of order s ∼ 1 pc and beyond, any potential sample of genuine wide binaries in TGAS cannot be easily distinguished from ionized former wide binaries, moving groups, or contamination from randomly aligned stars.

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A fast 2D image reconstruction algorithm from 1D data for the Gaia mission

Cited by 20 publications

References 6 publications

Gravitationally lensed quasars in Gaia – II. Discovery of 24 lensed quasars

Gravitationally lensed quasars in Gaia – II. Discovery of 24 lensed quasars

TheGaiamission

Wide binaries in Tycho-Gaia: search method and the distribution of orbital separations

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