O. Durney

The Large Binocular Telescope mid-infrared camera (LMIRcam): final design and status

We report on the final design and the fabrication status of LMIRcam - a mid-infrared imager/spectrograph that will operate behind the Large Binocular Telescope Interferometer (LBTI) primarily at wavelengths between 3 and 5um (the astronomical L- and M-bands). Within LMIRcam a pair of diamond-turned biconic mirrors re-images a ten arcsecond square field onto a 1024x1024 HAWAII-1RG 5.1um cutoff array. The re-imaging optics provide two pupil planes for the placement of filters and grisms as well as an intermediate image plane. Flexible readout electronics enable operating modes ranging from high frame rate broadband imaging at the longest wavelengths to low background R=400 spectroscopy at shorter wavelengths. The LBTI will provide LMIRcam with a diffraction limited two-mirror PSF with first null dictated by the 14.4 meter separation of the two LBT mirror centers (22.8 meter baseline from edge to edge).

Nulling Data Reduction and On-sky Performance of the Large Binocular Telescope Interferometer

National Aeronautics and Space Administration, Exoplanet Exploration Program; National Aeronautics and Space Administration; European Union through ERC [279973]

ARGOS - The laser guide star system for the LBT

ARGOS is the Laser Guide Star adaptive optics system for the Large Binocular Telescope. Aiming for a wide field adaptive optics correction, ARGOS will equip both sides of LBT with a multi laser beacon system and corresponding wavefront sensors, driving LBTs adaptive secondary mirrors. Utilizing high power pulsed green lasers the artificial beacons are generated via Rayleigh scattering in earths atmosphere. ARGOS will project a set of three guide stars above each of LBTs mirrors in a wide constellation. The returning scattered light, sensitive particular to the turbulence close to ground, is detected in a gated wavefront sensor system. Measuring and correcting the ground layers of the optical distortions enables ARGOS to achieve a correction over a very wide field of view. Taking advantage of this wide field correction, the science that can be done with the multi object spectrographs LUCIFER will be boosted by higher spatial resolution and strongly enhanced flux for spectroscopy. Apart from the wide field correction ARGOS delivers in its ground layer mode, we foresee a diffraction limited operation with a hybrid Sodium laser Rayleigh beacon combination.

First AO-corrected interferometry with LBTI: Steps towards routine coherent imaging observations

We report the first phased images using adaptive optics correction from the Large Binocular Telescope Interferometer. LBTI achieved first fringes in late 2010, with seeing-limited operation. Initial tests verified the feasibility of the setup and allowed us to characterize the phase variations from both the atmosphere and mechanical vibrations. Integration of the secondary-base AO systems was carried out in spring 2011 and spring 2012 for the right and left side respectively. Single aperture, diffraction-limited, operation has been commissioned and is used as a productive mode of the LBTI with the LMIRCam subsystem. We describe the initial observation for dual aperture observations and coherent imaging results.

The HOSTS Survey—Exozodiacal Dust Measurements for 30 Stars

The HOSTS (Hunt for Observable Signatures of Terrestrial Systems) survey searches for dust near the habitable zones (HZs) around nearby, bright main sequence stars. We use nulling interferometry in N band to suppress the bright stellar light and to probe for low levels of HZ dust around the 30 stars observed so far. Our overall detection rate is 18%, including four new detections, among which are the first three around Sun-like stars and the first two around stars without any previously known circumstellar dust. The inferred occurrence rates are comparable for early type and Sun-like stars, but decrease from 60 (+16/-21)% for stars with previously detected cold dust to 8 (+10/-3)% for stars without such excess, confirming earlier results at higher sensitivity. For completed observations on individual stars, our sensitivity is five to ten times better than previous results. Assuming a lognormal excess luminosity function, we put upper limits on the median HZ dust level of 13 zodis (95% confidence) for a sample of stars without cold dust and of 26 zodis when focussing on Sun-like stars without cold dust. However, our data suggest that a more complex luminosity function may be more appropriate. For stars without detectable LBTI excess, our upper limits are almost reduced by a factor of two, demonstrating the strength of LBTI target vetting for future exo-Earth imaging missions. Our statistics are so far limited and extending the survey is critical to inform the design of future exo-Earth imaging surveys.

SOUL: The Single conjugated adaptive Optics Upgrade for LBT

We present here SOUL: the Single conjugated adaptive Optics Upgrade for LBT. Soul will upgrade the wavefront sensors replacing the existing CCD detector with an EMCCD camera and the rest of the system in order to enable the closed loop operations at a faster cycle rate and with higher number of slopes. Thanks to reduced noise, higher number of pixel and framerate, we expect a gain (for a given SR) around 1.5–2 magnitudes at all wavelengths in the range 7.5 70% in I-band and 0.6asec seeing) and the sky coverage will be multiplied by a factor 5 at all galactic latitudes. Upgrading the SCAO systems at all the 4 focal stations, SOUL will provide these benefits in 2017 to the LBTI interferometer and in 2018 to the 2 LUCI NIR spectro-imagers. In the same year the SOUL correction will be exploited also by the new generation of LBT instruments: V-SHARK, SHARK-NIR and iLocater.

TIGER: A High Contrast infrared imager for the Giant Magellan Telescope

The Thermal Infrared imager for the GMT which provides Extreme contrast and Resolution (TIGER) is intended as a small-scale, targeted instrument capable of detecting and characterizing exoplanets and circumstellar disks, around both young systems in formation, and more mature systems in the solar neighborhood. TIGER can also provide general purpose infrared imaging at wavelengths from 1.5-14 μm. The instrument will utilize the facility adaptive optics (AO) system. With its operation at NIR to MIR wavelengths (where good image quality is easier to achieve), and much of the high-impact science using modestly bright guide stars, the instrument can be used early in the operation of the GMT. The TIGER concept is a dual channel imager and low resolution spectrometer, with high contrast modes of observations to fulfill the above science goals. A long wavelength channel (LWC) will cover 7-14 μm wavelength, while a short wavelength channel (SWC) will cover the 1.5-5 μm wavelength region. Both channels will have a 30° FOV. In addition to imaging, low-resolution spectroscopy (R=300) is possible with TIGER for both the SWC and LWC, using insertable grisms.

Fabrication and testing of germanium grisms for LMIRcam

We diamond fly cut 2 sets of germanium grisms for the LMIRcam 3-5 micron Fizeau imager for the combined focus of the Large Binocular Telescope (LBT). The grisms mount in a filter wheel near a pupil to enable moderate resolution (R~300) spectroscopy. Both sets have a measured blaze angle of 2.9°. The first set has a groove period of 40 lines/mm and will be used in first order with peak efficiency at 3.6 μm. The second set has 32 lines/mm. It can operate in first order with an efficiency peak near 4.4 μm and in second order with a peak near 2.3 μm. First results from testing the grisms in the instrument on the sky with the LBT are presented.

Testing and Alignment of the LBTI

The Large Binocular Telescope Interferometer (LBTI) has been developed and tested and is almost ready to be installed to LBT mount. In preparation for installation, testing of the beam combination and phasing of the system have been developed. The testing is currently in progress. The development of a telescope simulator for LBTI has allowed verification of phasing and alignment with a broad band source at 10 microns2. Vibration tests with the LBTI mounted to the LBT were carried out in July 2008, with both seismic accelerometers and an internal optical interferometric measurement. The results have allowed identification of potential vibration sources on the telescope. Plans for a Star Simulator that illuminates each LBT aperture at the prime focus with two artificial point sources derived from a single point source via fiber optics are presented. The Star Simulator will allow testing of LBTI with the telescope and the adaptive secondaries in particular. Testing with the Star Simulator will allow system level testing of LBTI on the telescope, without need to use on-sky time. Testing of the Star Simulator components are presented to verify readiness for use with the LBTI.

MagAO-X: project status and first laboratory results

MagAO-X is an entirely new extreme adaptive optics system for the Magellan Clay 6.5 m telescope, funded by the NSF MRI program starting in Sep 2016. The key science goal of MagAO-X is high-contrast imaging of accreting protoplanets at Hα. With 2040 actuators operating at up to 3630 Hz, MagAO-X will deliver high Strehls (> 70%), high resolution (19 mas), and high contrast (< 1 × 10-4 ) at Hα (656 nm). We present an overview of the MagAO-X system, review the system design, and discuss the current project status.