<i>SPITZER</i>IRAC PHOTOMETRY FOR TIME SERIES IN CROWDED FIELDS

Novati, S. Calchi; Gould, Andrew; Yee, Jennifer C.; Beichman, C. A.; Bryden, G.; Carey, Sean; Fausnaugh, Michael; Gaudi, B. Scott; Henderson, Calen B.; Pogge, Richard W.; Shvartzvald, Yossi; Wibking, Benjamin D.; Zhu, Wei; Team, Spitzer; Udalski, A.; Poleski, R.; Pawlak, M.; Szymański, M. K.; Skowron, J.; Mróz, P.; Kozłowski, S.; Wyrzykowski, Ł.; Pietrukowicz, P.; Pietrzyński, G.; Ulaczyk, K.

doi:10.1088/0004-637x/814/2/92

Cited by 61 publications

(79 citation statements)

References 34 publications

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“…The event was indeed faint in Spitzer images, reaching = L 15.9 eff , fainter than the assumed sensitivity limit. However, the data were reduced using the new algorithm for Spitzer photometry in crowded fields (Calchi Novati et al 2015b), resulting in the required high precision. It is important to note that while the peak L eff was similar to the estimation based on the ground-based light curve, it occurred at a later time and with lower magnification than predicted.…”

Section: Spitzer Observationsmentioning

confidence: 99%

The First Simultaneous Microlensing Observations by Two Space Telescopes: Spitzer and Swift Reveal a Brown Dwarf in Event Ogle-2015-BLG-1319

Shvartzvald¹,

Li²,

Udalski³

et al. 2016

ApJ

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Simultaneous observations of microlensing events from multiple locations allow for the breaking of degeneracies between the physical properties of the lensing system, specifically by exploring different regions of the lens plane and by directly measuring the "microlens parallax." We report the discovery of a 30-65M J brown dwarf orbiting a K dwarf in the microlensing event OGLE-2015-BLG-1319. The system is located at a distance of ∼5 kpc toward the Galactic Bulge. The event was observed by several ground-based groups as well as by Spitzer and Swift, allowing a measurement of the physical properties. However, the event is still subject to an eight-fold degeneracy, in particular the well-known close-wide degeneracy, and thus the projected separation between the two lens components is either ∼0.25 au or ∼45 au. This is the first microlensing event observed by Swift, with the UVOT camera. We study the region of microlensing parameter space to which Swift is sensitive, finding that though Swift could not measure the microlens parallax with respect to ground-based observations for this event, it can be important for other events. Specifically, it is important for detecting nearby brown dwarfs and free-floating planets in high magnification events.

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Section: Spitzer Observationsmentioning

confidence: 99%

The First Simultaneous Microlensing Observations by Two Space Telescopes: Spitzer and Swift Reveal a Brown Dwarf in Event Ogle-2015-BLG-1319

Shvartzvald¹,

Li²,

Udalski³

et al. 2016

ApJ

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“…Since this requirement was met, these observations were initiated, and were ultimately conducted during the period 7930.5-7966.9 (∼36.4 days), with both dates set essentially by the spacecraft's Sun-angle restrictions. Spitzer images were taken in the 3.6 μm channel of the IRAC camera, and the data were reduced with a specially developed version of point response function photometry (Calchi Novati et al 2015b). …”

Section: Observations and Datamentioning

confidence: 99%

OGLE-2017-BLG-0329L: A Microlensing Binary Characterized with Dramatically Enhanced Precision Using Data from Space-based Observations

Han¹,

Novati²,

Udalski³

et al. 2018

ApJ

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Mass measurements of gravitational microlenses require one to determine the microlens parallax π E , but precise π E measurement, in many cases, is hampered due to the subtlety of the microlens-parallax signal combined with the difficulty of distinguishing the signal from those induced by other higher-order effects. In this work, we present the 1 analysis of the binary-lens event OGLE-2017-BLG-0329, for which π E is measured with a dramatically improved precision using additional data from space-based Spitzer observations. We find that while the parallax model based on the ground-based data cannot be distinguished from a zero-π E model at the 2σ level, the addition of the Spitzer data enables us to identify two classes of solutions, each composed of a pair of solutions according to the wellknown ecliptic degeneracy. It is found that the space-based data reduce the measurement uncertainties of the north and east components of the microlens-parallax vector E p by factors ∼18 and ∼4, respectively. With the measured microlens parallax combined with the angular Einstein radius measured from the resolved caustic crossings, we find that the lens is composed of a binary with component masses of either (M 1 , M 2 )∼(1.1, 0.8) M e or ∼(0.4, 0.3) M e according to the two solution classes. The first solution is significantly favored but the second cannot be securely ruled out based on the microlensing data alone. However, the degeneracy can be resolved from adaptive optics observations taken ∼10 years after the event.

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“…The Spitzer data were reduced using the algorithm specialized for Spitzer photometry in crowded fields (Calchi Novati et al 2015b). For the individual data sets, we readjust error bars by…”

Section: Observationmentioning

confidence: 99%

Ogle-2015-BLG-0196: Ground-Based Gravitational Microlens Parallax Confirmed by Space-Based Observation

Han

Udalski

Gould

et al. 2017

ApJ

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In this paper, we present an analysis of the binary gravitational microlensing event OGLE-2015-BLG-0196. The event lasted for almost a year, and the light curve exhibited significant deviations from the lensing model based on the rectilinear lens-source relative motion, enabling us to measure the microlens parallax. The ground-based microlens parallax is confirmed by the data obtained from space-based microlens observations using the Spitzer telescope. By additionally measuring the angular Einstein radius from the analysis of the resolved caustic crossing, the physical parameters of the lens are determined up to the twofold degeneracy, u 0 <0 and u 0 >0, solutions caused by the well-known "ecliptic" degeneracy. It is found that the binary lens is composed of two M dwarf stars with similar masses, M 1 =0.38±0.04 M e (0.50±0.05 M e ) and M 2 =0.38±0.04 M e (0.55±0.06 M e ), and the distance to the lens is D L =2.77±0.23 kpc (3.30±0.29 kpc). Here the physical parameters outside and inside the parentheses are for the u 0 <0 and u 0 >0 solutions, respectively.

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SPITZERIRAC PHOTOMETRY FOR TIME SERIES IN CROWDED FIELDS

Cited by 61 publications

References 34 publications

The First Simultaneous Microlensing Observations by Two Space Telescopes: Spitzer and Swift Reveal a Brown Dwarf in Event Ogle-2015-BLG-1319

The First Simultaneous Microlensing Observations by Two Space Telescopes: Spitzer and Swift Reveal a Brown Dwarf in Event Ogle-2015-BLG-1319

OGLE-2017-BLG-0329L: A Microlensing Binary Characterized with Dramatically Enhanced Precision Using Data from Space-based Observations

Ogle-2015-BLG-0196: Ground-Based Gravitational Microlens Parallax Confirmed by Space-Based Observation

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