The two-colour EMCCD instrument for the Danish 1.54 m telescope and SONG

Skottfelt, J.; Bramich, D. M.; Hundertmark, M.; Jørgensen, U. G.; Michaelsen, Niels; Kjærgaard, P.; Southworth, J.; Sørensen, Anton Norup; Andersen, M. Fredslund; Andersen, M. I.; Christensen‐Dalsgaard, J.; Frandsen, S.; Grundahl, F.; Harpsøe, K.; Kjeldsen, H.; Pallé, P. L.

doi:10.1051/0004-6361/201425260

Cited by 58 publications

(66 citation statements)

References 44 publications

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“…The observations were taken by the EMCCD camera at 10 Hz (Skottfelt et al 2015) in V and I, but only the I-band data were used in the analysis.…”

Section: Full Kepler Orbits In Microlensingmentioning

confidence: 99%

OGLE-2016-BLG-1190Lb: The First Spitzer Bulge Planet Lies Near the Planet/Brown-dwarf Boundary

Ryu¹,

Yee²,

Udalski³

et al. 2017

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We report the discovery of OGLE-2016-BLG-1190Lb, which is likely to be the first Spitzer microlensing planet in the Galactic bulge/bar, an assignation that can be confirmed by two epochs of high-resolution imaging of the combined source-lens baseline object. The planet's mass, M p =13.4±0.9 M J , places it right at the deuteriumburning limit, i.e., the conventional boundary between "planets" and "brown dwarfs." Its existence raises the question of whether such objects are really "planets" (formed within the disks of their hosts) or "failed stars" (lowmass objects formed by gas fragmentation). This question may ultimately be addressed by comparing disk and bulge/bar planets, which is a goal of the Spitzer microlens program. The host is a G dwarf, M host =0.89±0.07 M e , and the planet has a semimajor axis a∼2.0 au. We use Kepler K2 Campaign 9 microlensing data to break the lens-mass degeneracy that generically impacts parallax solutions from Earth-Spitzer observations alone, which is the first successful application of this approach. The microlensing data, derived primarily from near-continuous, ultradense survey observations from OGLE, MOA, and three KMTNet telescopes, contain more orbital information than for any previous microlensing planet, but not quite enough to accurately specify the full orbit. However, these data do permit the first rigorous test of microlensing orbital-motion measurements, which are typically derived from data taken over <1% of an orbital period.

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“…The observations were taken by the EMCCD camera at 10 Hz (Skottfelt et al 2015) in V and I, but only the I-band data were used in the analysis.…”

Section: Full Kepler Orbits In Microlensingmentioning

confidence: 99%

OGLE-2016-BLG-1190Lb: The First Spitzer Bulge Planet Lies Near the Planet/Brown-dwarf Boundary

Ryu¹,

Yee²,

Udalski³

et al. 2017

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“…Taking the mirror and the sensitivity of the camera into consideration, it is possible to cover a wavelength range of between 650 nm to 1050 nm, corresponding roughly to a combination of SDSS i + z filters (Bessell 2005). More details about the instrument can be found in Skottfelt et al (2015b).…”

Section: Telescope and Instrumentmentioning

confidence: 99%

Exploring the crowded central region of ten Galactic globular clusters using EMCCDs

Jaimes¹,

Bramich²,

Skottfelt³

et al. 2016

A&A

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Aims. We aim to obtain time-series photometry of the very crowded central regions of Galactic globular clusters; to obtain better angular resolution than has been previously achieved with conventional CCDs on ground-based telescopes; and to complete, or improve, the census of the variable star population in those stellar systems. Methods. Images were taken using the Danish 1.54-m Telescope at the ESO observatory at La Silla in Chile. The telescope was equipped with an electron-multiplying CCD, and the short-exposure-time images obtained (ten images per second) were stacked using the shift-and-add technique to produce the normal-exposure-time images (minutes). Photometry was performed via difference image analysis. Automatic detection of variable stars in the field was attempted. Results. The light curves of 12 541 stars in the cores of ten globular clusters were statistically analysed to automatically extract the variable stars. We obtained light curves for 31 previously known variable stars (3 long-period irregular, 2 semi-regular, 20 RR Lyrae, 1 SX Phoenicis, 3 cataclysmic variables, 1 W Ursae Majoris-type and 1 unclassified) and we discovered 30 new variables (16 long-period irregular, 7 semi-regular, 4 RR Lyrae, 1 SX Phoenicis and 2 unclassified). Fluxes and photometric measurements for these stars are available in electronic form through the Strasbourg astronomical Data Center.

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“…The TCI is a lucky imager designed for simultaneous two-colour photometry, using Electron Multiplying CCD (EMCCD) detectors. We give a brief summary of the instrument, with a more detailed description available in Skottfelt et al (2015b). The light arriving at the instrument is split between the two cameras using a dichroic with a cut-off wavelength of 655 nm.…”

Section: Observationsmentioning

confidence: 99%

High-resolution Imaging of Transiting Extrasolar Planetary systems (HITEP)

Evans

Southworth

Maxted

et al. 2016

A&A

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Context. Wide binaries are a potential pathway for the formation of hot Jupiters. The binary fraction among host stars is an important discriminator between competing formation theories, but has not been well characterised. Additionally, contaminating light from unresolved stars can significantly affect the accuracy of photometric and spectroscopic measurements in studies of transiting exoplanets. Aims. We observed 101 transiting exoplanet host systems in the Southern hemisphere in order to create a homogeneous catalogue of both bound companion stars and contaminating background stars, in an area of the sky where transiting exoplanetary systems have not been systematically searched for stellar companions. We investigate the binary fraction among the host stars in order to test theories for the formation of hot Jupiters. Methods. Lucky imaging observations from the Two Colour Instrument on the Danish 1.54 m telescope at La Silla were used to search for previously unresolved stars at small angular separations. The separations and relative magnitudes of all detected stars were measured. For 12 candidate companions to 10 host stars, previous astrometric measurements were used to evaluate how likely the companions are to be physically associated. Results. We provide measurements of 499 candidate companions within 20 arcsec of our sample of 101 planet host stars. 51 candidates are located within 5 arcsec of a host star, and we provide the first published measurements for 27 of these. Calibrations for the plate scale and colour performance of the Two Colour Instrument are presented. Conclusions. We find that the overall multiplicity rate of the host stars is 38 +17 −13 %, consistent with the rate among solar-type stars in our sensitivity range, suggesting that planet formation does not preferentially occur in long period binaries compared to a random sample of field stars. Long period stellar companions (P > 10 yr) appear to occur independently of short period companions, and so the population of close-in stellar companions is unconstrained by our study.

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The two-colour EMCCD instrument for the Danish 1.54 m telescope and SONG

Cited by 58 publications

References 44 publications

OGLE-2016-BLG-1190Lb: The First Spitzer Bulge Planet Lies Near the Planet/Brown-dwarf Boundary

OGLE-2016-BLG-1190Lb: The First Spitzer Bulge Planet Lies Near the Planet/Brown-dwarf Boundary

Exploring the crowded central region of ten Galactic globular clusters using EMCCDs

High-resolution Imaging of Transiting Extrasolar Planetary systems (HITEP)

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