Spartan infrared camera: high-resolution imaging for the SOAR Telescope

Loh, E. D.; Biel, Jason D.; Chen, Jianjun; Davis, Michael W.; Laporte, R.; Loh, Owen Y.

doi:10.1117/12.551808

Cited by 7 publications

(9 citation statements)

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“…The spot diagrams (Fig. 3 of Loh et al 2004) show that all of the spots are well within the Airy disk, for which the diameter is 1:23λf, where f is the ratio between the focal length and the aperture. This is not surprising: it must be so for diffraction-limited optics.…”

Section: Optical Designmentioning

confidence: 96%

“…The image width of the SOAR Telescope with tip/tilt correction of atmospheric turbulence was predicted to be spectacular in the near-infrared bands (Loh et al 2004), where, for example, the image width in the K band with median seeing was predicted to be 140 mas. Because of this, we set high design goals: namely, (1) to resolve the diffraction limit in the H and K bands, which means sampling at 40 mas, and (2) to cover a 5′ field over which tip-tilt correction is significant.…”

Section: Design Goalsmentioning

confidence: 99%

“…The optical design concept is a pair of off-axis segments of parabolas (Loh et al 2004). The focus of the first parabola is at the focus of the telescope; this parabola collimates the light beam.…”

Section: Optical Designmentioning

confidence: 99%

“…The image quality of the design is excellent. The Strehl ratio of the optical design is quite high (Loh et al 2004). The mean Strehl ratio across the field is greater than 98% for the high-resolution channel.…”

Section: Optical Designmentioning

confidence: 99%

“…The first published observations using the camera are described by Loh et al (2010) and Loh et al (2011). Loh et al (2004) described the instrument when fabrication was half-done and before testing started. This article presents the final design, results of laboratory tests, and performance on the SOAR Telescope.…”

Section: Introductionmentioning

confidence: 99%

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Spartan Infrared Camera, a High-Resolution Imager for the SOAR Telescope: Design, Tests, and On-Telescope Performance

Loh¹,

Biel²,

Davis³

et al. 2012

Publications of the Astronomical Society of the Pacific

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The Spartan Infrared Camera provides tip-tilt corrected imaging for the SOAR Telescope in the 900-2500 nm spectral range with four 2048 × 2048 HAWAII-2 detectors. The camera has two plate scales: highresolution (40 mas pixel À1 ) for future diffraction-limited sampling in the H and K bands and wide-field (66 mas pixel À1 ) to cover a 5 0 × 5 0 field, over which tip-tilt correction is substantial. The design is described in detail. Except for CaF 2 field-flattening lenses, the optics are aluminum mirrors to thermally match the aluminum cryogenic-optical box in which the optics mount. The design minimizes the tilt of the optics as the instrument rotates on the Nasmyth port of the telescope. Two components of the gravitational torque on an optic are eliminated by symmetry, and the third component is minimized by balancing the optic. The optics (including the off-axis aspherical mirrors) were aligned with precise metrology. For the detector assembly, Henein pivots are used to provide frictionless, thermally compliant, lubricant-free, and thermally conducting rotation of the detectors. The heat load is 14 W for an ambient temperature of 10°C. Cooling down takes 40 hr. An activated-charcoal getter controls permeation through the large Viton O-ring for at least nine months. We present maps of the image distortion, which amount to tens of pixels at the greatest. The wavelength of the narrowband filters shift with position in the sky. The measured Strehl ratio of the camera itself is 0.81-0.84 at λ1650 nm. The width of the best K-band image was 260 mas in unexceptional seeing measured after tuning the telescope and before moving the telescope. Since images are normally taken after pointing the telescope to a different field, this supports the idea that the image quality could be improved by better control of the focus and the shape of the primary mirror. The instrument has proved to be capable of producing images that can be stitched together to measure faint, extended features and to produce photometry that agree internally to better than 0.01 mag and are well calibrated to 2MASS stars in the range of 12 < K < 16.

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Section: Optical Designmentioning

confidence: 96%

Section: Design Goalsmentioning

confidence: 99%

Section: Optical Designmentioning

confidence: 99%

Section: Optical Designmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Spartan Infrared Camera, a High-Resolution Imager for the SOAR Telescope: Design, Tests, and On-Telescope Performance

Loh¹,

Biel²,

Davis³

et al. 2012

Publications of the Astronomical Society of the Pacific

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The Close AGN Reference Survey (CARS)

Rothberg¹,

Busch²,

Dierkes³

et al. 2019

A&A

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The absence of star formation in the bar region that has been reported for some galaxies can theoretically be explained by shear. However, it is not clear how star-forming (SF) bars fit into this picture and how the dynamical state of the bar is related to other properties of the host galaxy. We used integral-field spectroscopy from VLT/MUSE to investigate how star formation within bars is connected to structural properties of the bar and the host galaxy. We derived spatially resolved Hα fluxes from MUSE observations from the CARS survey to estimate star formation rates in the bars of 16 nearby (0.01 < z < 0.06) disc galaxies with stellar masses between 10 10 M and 10 11 M . We further performed a detailed multicomponent photometric decomposition on images derived from the data cubes. We find that bars clearly divide into SF and non-star-forming (non-SF) types, of which eight are SF and eight are non-SF. Whatever the responsible quenching mechanism is, it is a quick process compared to the lifetime of the bar. The star formation of the bar appears to be linked to the flatness of the surface brightness profile in the sense that only the flattest bars (n bar ≤ 0.4) are actively SF SFR b > 0.5 M yr −1 . Both parameters are uncorrelated with Hubble type. We find that star formation is 1.75 times stronger on the leading than on the trailing edge and is radially decreasing. The conditions to host non-SF bars might be connected to the presence of inner rings. Additionally, from testing an AGN feeding scenario, we report that the star formation rate of the bar is uncorrelated with AGN bolometric luminosity. The results of this study may only apply to type-1 AGN hosts and need to be confirmed for the full population of barred galaxies.

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Fire Spectroscopy of Five Late-Type T Dwarfs Discovered With the Wide-Field Infrared Survey Explorer

Burgasser

Cushing

Kirkpatrick

et al. 2011

ApJ

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We present the discovery of five late-type T dwarfs identified with the Wide-field Infrared Survey Explorer (WISE). Low-resolution near-infrared spectroscopy obtained with the Magellan Folded-port InfraRed Echellette (FIRE) reveal strong H 2 O and CH 4 absorption in all five sources, and spectral indices and comparison to spectral templates indicate classifications ranging from T5.5 to T8.5:. The spectrum of the latest-type source, WISE J1812+2721, is an excellent match to that of the T8.5 companion brown dwarf Wolf 940B. WISE-based spectrophotometric distance estimates place these T dwarfs at 12-13 pc from the Sun, assuming they are single. Preliminary fits of the spectral data to the atmosphere models of Saumon & Marley indicate effective temperatures ranging from 600 K to 930 K, both cloudy and cloud-free atmospheres, and a broad range of ages and masses. In particular, two sources show evidence of both low surface gravity and cloudy atmospheres, tentatively supporting a trend noted in other young brown dwarfs and exoplanets. In contrast, the high proper motion T dwarf WISE J2018−7423 exhibits a suppressed K-band peak and blue spectrophotometric J − K colors indicative of an old, massive brown dwarf; however, it lacks the broadened Y -band peak seen in metal-poor counterparts. These results illustrate the broad diversity of low-temperature brown dwarfs that will be uncovered with WISE.

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Spartan infrared camera: high-resolution imaging for the SOAR Telescope

Cited by 7 publications

References 1 publication

Spartan Infrared Camera, a High-Resolution Imager for the SOAR Telescope: Design, Tests, and On-Telescope Performance

Spartan Infrared Camera, a High-Resolution Imager for the SOAR Telescope: Design, Tests, and On-Telescope Performance

The Close AGN Reference Survey (CARS)

Fire Spectroscopy of Five Late-Type T Dwarfs Discovered With the Wide-Field Infrared Survey Explorer

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