The Slicer Combined with an Array of Lenslets for Exoplanet Spectroscopy (SCALES) will be the first facility-class integral field spectrograph (IFS) to operate between 2-5 microns. Expected to see first light at W. M. Keck Observatory in 2025, SCALES will extend the parameter space of directly imaged exoplanets to those that are colder, and thus older. SCALES will perform high-contrast imaging of these objects and other targets including protoplanetary disks, Solar System objects, and supernovae. Interferometric techniques such as non-redundant aperture masking (NRM) have been demonstrated to improve spatial resolution at high contrasts. Aperture masking turns a telescope into an interferometer by blocking the pupil with an opaque mask with some number of circular holes. Here we present the final designs for the non-redundant masks that will be integrated into SCALES. We outline their design, manufacturing, characterization, and integration processes. We also present the injection and recovery of several planet and disk companion models into mock SCALES science frames to assess the performance of the selected designs.
Holographic aperture masking (HAM) is an imaging technique in which a conventional telescope pupil is made into an interferometric array by means of a diffractive liquid-crystal phase mask. HAM allows for angular resolution that approaches and goes within the classical diffraction limit, while simultaneously increasing the throughput on the detector compared to traditional SAM, which uses a simple transmissive pupil plane mask. HAM creates interference fringes that provide phase and power information for each pair of holes in the mask, making the technique especially useful for the detection of close-in asymmetric structures surrounding stars, such as stellar or planetary companions, or protoplanetary disks. We present on-sky tests of an upgraded HAM mask installed in the Keck I OSIRIS imager. Observations were taken at J-band (1.28μm) of the known binary HD 44927 and single star HD 13249, the latter being used as a reference for calibration of instrumental errors. Using the SAMpy data reduction pipeline and modifying it for the Keck I HAM mask, Fourier observables were extracted and analyzed. We constrained astrometric and photometric measurements of the HD 44927 companion relative to its host star using a grid-fit companion model, producing orbital parameters to compare to previous measurements made with other interferometric imaging techniques.
The first scientific observations with adaptive optics (AO) at W. M. Keck Observatory (WMKO) began in 1999. Through 2023, over 1200 refereed science papers have been published using data from the WMKO AO systems. The scientific competitiveness of AO at WMKO has been maintained through a continuous series of AO and instrument upgrades and additions. This tradition continues with AO being a centerpiece of WMKO’s scientific strategic plan for 2035. We will provide an overview of the current and planned AO projects from the context of this strategic plan. The current projects include implementation of new real-time controllers, the KAPA laser tomography system and the HAKA high-order deformable mirror system, the development of multiple advanced wavefront sensing and control techniques, the ORCAS space-based guide star project, and three new AO science instruments. We will also summarize steps toward the future strategic directions which are centered on ground-layer, visible and high-contrast AO.
SCALES (Slicer Combined with Array of Lenslets for Exoplanet Spectroscopy) is the next-generation, diffraction-limited, thermal infrared, fully cryogenic, coronagraphic exoplanet spectrograph and imager for W.M. Keck Observatory. SCALES is fed by the Keck II Adaptive Optics bench. Both modes use common fore-optics to simplify the optical design and have individual detectors, which are JWST flight spares. The imager mode operates from 1 to 5 microns with selectable narrow- and broadband filters over a field of view 12.3 arcseconds on a side, and the integral field spectrograph mode operates from 2 to 5 microns with both low and mid spectral resolutions (R∼ 100 to R∼ 7500) over a field of view 2.15 arcseconds on a side. The diamond-turned aluminum optics, most of which are already delivered, with the rest being fabricated, provide low distortion, low wavefront error, and high throughput for all modes. The slicing unit, located behind the lenslet array, allows SCALES to reach heretofore unheard-of spatially-resolved spectral resolution for exoplanet and disc observations from the ground with a coronagraphic integral field spectrograph. The SCALES consortium includes UC Observatories, CalTech, W.M. Keck Observatory, the Indian Institute of Astrophysics, and the University of Durham, with over 40 science team members. We report on the overall design and project status during its ongoing fabrication phase, which started in early 2023.
SCALES (Slicer Combined with Array of Lenslets for Exoplanet Spectroscopy) is a 2 micron to 5 micron high-contrast lenslet-based Integral Field Spectrograph (IFS) designed to characterize exoplanets and their atmospheres. The SCALES medium-spectral-resolution mode uses a lenslet subarray with a 0.34 x 0.36 arcsecond field of view which allows for exoplanet characterization at increased spectral resolution. We explore the sensitivity limitations of this mode by simulating planet detections in the presence of realistic noise sources. We use the SCALES simulator scalessim to generate high-fidelity mock observations of planets that include speckle noise from their host stars, as well as other atmospheric and instrumental noise effects. We employ both angular and reference differential imaging as methods of disentangling speckle noise from the injected planet signals. These simulations allow us to assess the feasibility of speckle deconvolution for SCALES medium resolution data, and to test whether one approach outperforms another based on planet angular separations and contrasts.
The Slicer Combined with Array of Lenslets for Exoplanet Spectroscopy (SCALES) is an under-construction thermal infrared high-contrast integral field spectrograph that will be located at the W. M. Keck Observatory. SCALES will detect and characterize planets that are currently inaccessible to detailed study by operating at thermal (2 μm to 5 μm) wavelengths and leveraging integral-field spectroscopy to readily distinguish exoplanet radiation from residual starlight. SCALES’ wavelength coverage and medium-spectral-resolution (R ∼ 4,000) modes will also enable investigations of planet accretion processes. We explore the scientific requirements of additional custom gratings and filters for incorporation into SCALES that will optimally probe tracers of accretion in forming planets. We use ray-traced hydrogen emission line profiles (i.e., Brγ, Brα) and the SCALES end-to-end simulator, scalessim, to generate grids of high-fidelity mock datasets of accreting planetary systems with varying characteristics (e.g., Teff, planet mass, planet radius, mass accretion rate). In this proceeding, we describe potential specialized modes that best differentiate accretion properties and geometries from the simulated observations.
The Slicer Combined with Array of Lenslets for Exoplanet Spectroscopy (SCALES) is a 2 μm to 5 μm, high-contrast Integral Field Spectrograph (IFS) currently being built for Keck Observatory. With both low (R ≲ 250) and medium (R approximately 3500 to 7000) spectral resolution IFS modes, SCALES will detect and characterize significantly colder exoplanets than those accessible with near-infrared (approximately 1 μm to 2 μm) high-contrast spectrographs. This will lead to new progress in exoplanet atmospheric studies, including detailed characterization of benchmark systems that will advance the state of the art of atmospheric modeling. SCALES’ unique modes, while designed specifically for direct exoplanet characterization, will enable a broader range of novel (exo)planetary observations as well as galactic and extragalactic studies. Here we present the science cases that drive the design of SCALES. We describe an end-to-end instrument simulator that we use to track requirements and show simulations of expected science yields for each driving science case. We conclude with a discussion of preparations for early science when the instrument sees first light in approximately 2025.
The Slicer Combined with an Array of Lenslets for Exoplanet Spectroscopy (SCALES) instrument is a lenslet-based integral field spectrograph that will operate at 2 to 5 microns, imaging and characterizing colder (and thus older) planets than current high-contrast instruments. Its spatial resolution for distant science targets and/or close-in disks and companions could be improved via interferometric techniques such as sparse aperture masking. We introduce a nascent Python package, NRM-artist, that we use to design several SCALES masks to be non-redundant and to have uniform coverage in Fourier space. We generate high-fidelity mock SCALES data using the scalessim package for SCALES’ low spectral resolution modes across its 2 to 5 micron bandpass. We include realistic noise from astrophysical and instrument sources, including Keck adaptive optics and Poisson noise. We inject planet and disk signals into the mock datasets and subsequently recover them to test the performance of SCALES sparse aperture masking and to determine the sensitivity of various mask designs to different science signals.
We present the status and plans for the Keck All sky Precision Adaptive optics (KAPA) program. KAPA includes (1) an upgrade to the Keck I laser guide star adaptive optics (AO) facility to improve image quality and sky coverage, (2) the inclusion of AO telemetry-based point spread function estimates with all science exposures, (3) four key science programs, and (4) an educational component focused on broadening the participation of women and underrepresented groups in instrumentation. For this conference we focus on the KAPA upgrades since the 2020 SPIE proceedings1 including implementation of a laser asterism generator, wavefront sensor, real-time controller, asterism and turbulence simulators, the laser tomography system itself along with new operations software and science tools, and modifications to an existing near-infrared tip-tilt sensor to support multiple natural guide star and focus measurements. We will also report on the results of daytime and on-sky calibrations and testing.
We present the design of SCALES (Slicer Combined with Array of Lenslets for Exoplanet Spectroscopy) a new 2-5 micron coronagraphic integral field spectrograph under construction for Keck Observatory. SCALES enables low-resolution (R∼50) spectroscopy, as well as medium-resolution (R∼4,000) spectroscopy with the goal of discovering and characterizing cold exoplanets that are brightest in the thermal infrared. Additionally, SCALES has a 12x12” field-of-view imager that will be used for general adaptive optics science at Keck. We present SCALES’s specifications, its science case, its overall design, and simulations of its expected performance. Additionally, we present progress on procuring, fabricating and testing long lead-time components.
The direct characterization of exoplanetary systems with high contrast imaging is among the highest priorities for the broader exoplanet community. As large space missions will be necessary for detecting and characterizing exo-Earth twins, developing the techniques and technology for direct imaging of exoplanets is a driving focus for the community. For the first time, JWST will directly observe extrasolar planets at mid-infrared wavelengths beyond 5 μm, deliver detailed spectroscopy revealing much more precise chemical abundances and atmospheric conditions, and provide sensitivity to analogs of our solar system ice-giant planets at wide orbital separations, an entirely new class of exoplanet. However, in order to maximise the scientific output over the lifetime of the mission, an exquisite understanding of the instrumental performance of JWST is needed as early in the mission as possible. In this paper, we describe our 55-hour Early Release Science Program that will utilize all four JWST instruments to extend the characterisation of planetary mass companions to ∼15-20 μm as well as image a circumstellar disk in the mid-infrared with unprecedented sensitivity. Our program will also assess the performance of the observatory in the key modes expected to be commonly used for exoplanet direct imaging and spectroscopy, optimize data calibration and processing, and generate representative datasets that will enable a broad user base to effectively plan for general observing programs in future cycles.
We present the status and plans for the Keck All sky Precision Adaptive optics (KAPA) program. KAPA includes four key science programs, an upgrade to the Keck I laser guide star (LGS) adaptive optics (AO) facility to improve image quality and sky coverage, AO telemetry based point spread function (PSF) estimates for all science exposures, and an educational component focused on broadening the participation of women and underrepresented groups in instrumentation. For the purpose of this conference we will focus on the AO facility upgrade which includes implementation of a new laser, wavefront sensor and real-time controller to support laser tomography, the laser tomography system itself, and modifications to an existing near-infrared tip-tilt sensor to support multiple natural guide star (NGS) and focus measurements.
We report on initial results from the largest infrared AO direct imaging survey searching for wide orbit (≳ 100 AU) massive exoplanets and brown dwarfs as companions around young nearby stars using Robo-AO at the 2.1-m telescope on Kitt Peak, Arizona. The occurrence rates of these rare substellar companions are critical to furthering our understanding of the origin of planetary-mass companions on wide orbits. The observing efficiency of Robo-AO allows us to conduct a survey an order of magnitude larger than previously possible. We commissioned a low-noise high-speed SAPHIRA near-infrared camera to conduct this survey and report on its sensitivity, performance, and data reduction process.
The progress achieved in implementing Point Spread Function reconstruction (PSF-R) capability at W. M. Keck Observatory (WMKO) is discussed. Observations of low-mass binary systems have been used to evaluate the improvements in astrometry and photometry using reconstructed PSFs. The on-sky performance of PSF-R is discussed by comparing the binary-fitting analysis using the reconstructed PSFs with the standard methods. We show that the PSFR in the NGS provides comparable performance to having a close reference star in the imaging science instrument. The on-sky troubleshooting efforts and the recent PSF-R technical developments are also presented. We find that the PSF-R reconstruction is more of a systems science problem that a post-processing problem. We close by discussing the lessons learned in the context of existing and future extremely large telescopes.
We are building a next-generation laser adaptive optics system, Robo-AO-2, for the UH 2.2-m telescope that will deliver robotic, diffraction-limited observations at visible and near-infrared wavelengths in unprecedented numbers. The superior Maunakea observing site, expanded spectral range and rapid response to high-priority events represent a significant advance over the prototype. Robo-AO-2 will include a new reconfigurable natural guide star sensor for exquisite wavefront correction on bright targets and the demonstration of potentially transformative hybrid AO techniques that promise to extend the faintness limit on current and future exoplanet adaptive optics systems.
The Thirty Meter Telescope (TMT) first light instrument IRIS (Infrared Imaging Spectrograph) will complete its preliminary design phase in 2016. The IRIS instrument design includes a near-infrared (0.85 - 2.4 micron) integral field spectrograph (IFS) and imager that are able to conduct simultaneous diffraction-limited observations behind the advanced adaptive optics system NFIRAOS. The IRIS science cases have continued to be developed and new science studies have been investigated to aid in technical performance and design requirements. In this development phase, the IRIS science team has paid particular attention to the selection of filters, gratings, sensitivities of the entire system, and science cases that will benefit from the parallel mode of the IFS and imaging camera. We present new science cases for IRIS using the latest end-to-end data simulator on the following topics: Solar System bodies, the Galactic center, active galactic nuclei (AGN), and distant gravitationally-lensed galaxies. We then briefly discuss the necessity of an advanced data management system and data reduction pipeline.
The Keck Planet Imager and Characterizer (KPIC) is a cost-effective upgrade path to the W.M. Keck observatory (WMKO) adaptive optics (AO) system, building on the lessons learned from first and second-generation extreme AO (ExAO) coronagraphs. KPIC will explore new scientific niches in exoplanet science, while maturing critical technologies and systems for future ground-based (TMT, EELT, GMT) and space-based planet imagers (HabEx, LUVOIR). The advent of fast low-noise IR cameras (IR-APD, MKIDS, electron injectors), the rapid maturing of efficient wavefront sensing (WFS) techniques (Pyramid, Zernike), small inner working angle (IWA) coronagraphs (e.g., vortex) and associated low-order wavefront sensors (LOWFS), as well as recent breakthroughs in high contrast high resolution spectroscopy, open new direct exoplanet exploration avenues that are complementary to planet imagers such as VLT-SPHERE and the Gemini Planet Imager (GPI). For instance, the search and detailed characterization of planetary systems on solar-system scales around late-type stars, mostly beyond SPHERE and GPI's reaches, can be initiated now at WMKO.
From 2008 December to 2012 September, the NICI (Near-Infrared Coronagraphic Imager at the Gemini-South 8.1-m) Planet-Finding Campaign (Liu et al. 2010) obtained deep, high-contrast AO imaging of a carefully selected sample of over 200 young, nearby stars. In the course of the campaign, we discovered four co-moving brown dwarf companions: PZ Tel B (36±6 MJup, 16.4±1.0 AU), CD-35 2722B (31±8 MJup, 67±4 AU), HD 1160B (33+12 -9 MJup, 81± AU), and HIP 79797Bb (55+20-19MJup, 3 AU from the previously known brown dwarf companion HIP 79797Ba), as well as numerous stellar binaries. Three survey papers have been published to date, covering: 1) high mass stars (Nielsen et al. 2013), 2) debris disk stars (Wahhaj et al. 2013), and 3) stars which are members of nearby young moving groups (Biller et al. 2013). In addition, the Campaign has yielded new orbital constraints for the ~8-10 MJup planet Pic β (Nielsen et al. 2014) and a high precision measurement of the star-disk offset for the well-known disk around HR 4796A (Wahhaj et al. 2014). Here we discuss constraints placed on the distribution of wide giant exoplanets from the NICI Campaign, new substellar companion discoveries, and characterization both of exoplanets and circumstellar disks.
KEYWORDS: IRIS Consortium, Galactic astronomy, Iterated function systems, Stars, Astronomy, Space telescopes, James Webb Space Telescope, Signal to noise ratio, Imaging systems, Spectroscopy
IRIS (InfraRed Imaging Spectrograph) is a first light near-infrared diffraction limited imager and integral field
spectrograph being designed for the future Thirty Meter Telescope (TMT). IRIS is optimized to perform astronomical
studies across a significant fraction of cosmic time, from our Solar System to distant newly formed galaxies (Barton et
al. [1]). We present a selection of the innovative science cases that are unique to IRIS in the era of upcoming space and
ground-based telescopes. We focus on integral field spectroscopy of directly imaged exoplanet atmospheres, probing
fundamental physics in the Galactic Center, measuring 104 to 1010 M supermassive black hole masses, resolved
spectroscopy of young star-forming galaxies (1 < z < 5) and first light galaxies (6 < z < 12), and resolved spectroscopy
of strong gravitational lensed sources to measure dark matter substructure. For each of these science cases we use the
IRIS simulator (Wright et al. [2], Do et al. [3]) to explore IRIS capabilities. To highlight the unique IRIS capabilities, we
also update the point and resolved source sensitivities for the integral field spectrograph (IFS) in all five broadband
filters (Z, Y, J, H, K) for the finest spatial scale of 0.004" per spaxel. We briefly discuss future development plans for the
data reduction pipeline and quicklook software for the IRIS instrument suite.
KEYWORDS: Stars, Planets, Adaptive optics, Exoplanets, Imaging systems, Telescopes, Monte Carlo methods, Gemini Observatory, Point spread functions, Space telescopes
Our team is carrying out a multi-year observing program to directly image and characterize young extrasolar
planets using the Near-Infrared Coronagraphic Imager (NICI) on the Gemini-South 8.1-meter telescope. NICI
is the first instrument on a large telescope designed from the outset for high-contrast imaging, comprising a
high-performance curvature adaptive optics (AO) system with a simultaneous dual-channel coronagraphic imager.
Combined with state-of-the-art AO observing methods and data processing, NICI typically achieves ≈2
magnitudes better contrast compared to previous ground-based or
space-based planet-finding efforts, at separations
inside of ≈2". In preparation for the Campaign, we carried out efforts to identify previously unrecognized
young stars as targets, to develop a rigorous quantitative method for constructing our observing strategy, and to
optimize the combination of angular differential imaging and spectral differential imaging. The Planet-Finding
Campaign is in its second year, with first-epoch imaging of 174 stars already obtained out of a total sample of
300 stars. We describe the Campaign's goals, design, target selection, implementation, on-sky performance, and
preliminary results. The NICI Planet-Finding Campaign represents the largest and most sensitive imaging survey
to date for massive
(>~ 1 MJup) planets around other stars. Upon completion, the Campaign will establish the best
measurements to date on the properties of young gas-giant planets at
-> 5-10 AU separations. Finally, Campaign
discoveries will be well-suited to long-term orbital monitoring and detailed spectrophotometric followup with
next-generation planet-finding instruments.
We present a conceptual design for a Precision Radial Velocity Spectrograph (PRVS) for the Gemini telescope. PRVS is
a fibre fed high resolving power (R~70,000 at 2.5 pixel sampling) cryogenic echelle spectrograph operating in the near
infrared (0.95 - 1.8 microns) and is designed to provide 1 m/s radial velocity measurements. We identify the various
error sources to overcome in order to the required stability. We have constructed models simulating likely candidates
and demonstrated the ability to recover exoplanetary RV signals in the infrared. PRVS should achieve a total RV error of
around 1 m/s on a typical M6V star. We use these results as an input to a simulated 5-year survey of nearby M stars.
Based on a scaling of optical results, such a survey has the sensitivity to detect several terrestrial mass planets in the
habitable zone around nearby stars. PRVS will thus test theoretical planet formation models, which predict an abundance
of terrestrial-mass planets around low-mass stars.We have conducted limited experiments with a brass-board instrument
on the Sun in the infrared to explore real-world issues achieving better than 10 m/s precision in single 10 s exposures and
better than 5 m/s when integrated across a minute of observing.
We discuss observing strategy for the Near Infrared Coronagraphic Imager (NICI) on the 8-m Gemini South
telescope. NICI combines a number of techniques to attenuate starlight and suppress superspeckles: 1) coronagraphic
imaging, 2) dual channel imaging for Spectral Differential Imaging (SDI) and 3) operation in a fixed
Cassegrain rotator mode for Angular Differential Imaging (ADI). NICI will be used both in service mode and
for a dedicated 50 night planet search campaign. While all of these techniques have been used individually in
large planet-finding surveys, this is the first time ADI and SDI will be used with a coronagraph in a large survey.
Thus, novel observing strategies are necessary to conduct a viable planet search campaign.
The recent advent of laser guide star adaptive optics (LGS AO) on
the largest ground-based telescopes has enabled a wide range of high
angular resolution science, previously infeasible from ground-
and/or space-based observatories. As a result, scientific
productivity with LGS has seen enormous growth in the last few
years, with a factor of ~10 leap in publication rate compared to the
first decade of operation. Of the 54 refereed science papers to
date from LGS AO, half have been published in the last ~2 years, and
these LGS results have already made a significant impact in a number
of areas. At the same time, science with LGS AO can be considered
in its infancy, as astronomers and instrumentalists are only
begining to understand its efficacy for measurements such as
photometry, astrometry, companion detection, and quantitative
morphology. We examine the science impact of LGS AO in the last few
years of operations, largely due to the new system on the Keck II
10-meter telescope. We review currently achieved data quality,
including results from our own ongoing brown dwarf survey with Keck
LGS. We assess current and near-future performance with a critical
eye to LGS AO's capabilities and deficiencies. From both
qualitative and quantitative considerations, it is clear that the era
of regular and important science from LGS AO has arrived.
We present the coronagraphic and adaptive optics performance of the Gemini-South Near-Infrared Coronagraphic Imager (NICI). NICI includes a dual-channel imager for simultaneous spectral difference imaging, a dedicated 85-element curvature adaptive optics system, and a built-in Lyot coronagraph. It is specifically designed to survey for and image large extra-solar gaseous planets on the Gemini Observatory 8-meter telescope in Chile. We present the on-sky performance of the individual subsystems along with the end-to-end contrast curve. These are compared to our model predictions for the adaptive optics system, the coronagraph, and the spectral difference imaging.
The Near-Infrared Coronagraphic Imager (NICI) is a high-contrast AO imager at the
Gemini South telescope. The camera includes a coronagraphic mask and dual channel imaging
for Spectral Differential Imaging (SDI). The instrument can also be used in a fixed Cassegrain
Rotator mode for Angular Differential Imaging (ADI). While coronagraphy, SDI, and ADI have
been applied before in direct imaging searches for exoplanets. NICI represents the first time that
these 3 techniques can be combined. We present preliminary NICI commissioning data using
these techniques and show that combining SDI and ADI results in significant gains.
We present a discussion of the science drivers and design approach for a high-resolution, mid-infrared spectrograph for
the Thirty-Meter Telescope. The instrument will be integrated with an adaptive optics system optimized for the midinfrared;
as a consequence it is not significantly larger or more complex than similar instruments designed for use on
smaller telescopes. The high spatial and spectral resolution possible with such a design provides a unique scientific
capability. The design provides spectral resolution of up to 120,000 for the 4.5-25 μm region in a cross-dispersed format
that provides continuous spectral coverage of up to 2% to 14 μm. The basic concept is derived from the successful
TEXES mid-infrared spectrograph. To facilitate operation, there are separate imaging channels for the near-infrared and
the mid-infrared; both can be used for acquisition and the mid-infrared imaging mode can be used for science imaging
and for guiding. Because the spectrograph is matched to the diffraction limit of a 30-m telescope, gains in sensitivity are
roughly proportional to the square of the telescope diameter, opening up a volume within the Galaxy a thousand times
greater than existing instruments.
We briefly discuss the past, present, and future state of astronomical science with laser guide star adaptive optics (LGS AO). We present a tabulation of refereed science papers from LGS AO, amounting to a total of 23 publications as of May 2006. The first decade of LGS AO science (1995-2004) was marked by modest science productivity (≈1 paper/year), as LGS systems were being implemented and commissioned. The last two years have seen explosive science growth (≈1 paper/month), largely due to the new LGS system on the Keck II 10-meter telescope, and point to an exciting new era for high angular resolution science. To illustrate the achievable on-sky performance, we present an extensive collection of Keck LGS performance measurements from the first year of our brown dwarf near-IR imaging survey. We summarize the current strengths and weaknesses of LGS compared to Hubble Space Telescope, offer a list of desired improvements, and look forward to a bright future for LGS given its wide-scale implementation on large ground-based telescopes.
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