We have built and commissioned a prototype agitated non-circular core ber scrambler for precision spectroscopic radial velocity measurements in the near-infrared H band. We have collected the rst on-sky performance and modal noise tests of these novel bers in the near-infrared at H and K bands using the CSHELL spectrograph at the NASA InfraRed Telescope Facility (IRTF). We discuss the design behind our novel reverse injection of a red laser for co-alignment of star-light with the ber tip via a corneWe have built and commissioned a prototype agitated non-circular core fiber scrambler for precision spectroscopic radial velocity measurements in the near-infrared H band. We have collected the first on-sky performance and modal noise tests of these novel fibers in the near-infrared at H and K bands using the CSHELL spectrograph at the NASA InfraRed Telescope Facility (IRTF). We discuss the design behind our novel reverse injection of a red laser for co-alignment of star-light with the fiber tip via a corner cube and visible camera. We summarize the practical details involved in the construction of the fiber scrambler, and the mechanical agitation of the fiber at the telescope. We present radial velocity measurements of a bright standard star taken with and without the fiber scrambler to quantify the relative improvement in the obtainable blaze function stability, the line spread function stability, and the resulting radial velocity precision. We assess the feasibility of applying this illumination stabilization technique to the next generation of near-infrared spectrographs such as iSHELL on IRTF and an upgraded NIRSPEC at Keck. Our results may also be applied in the visible for smaller core diameter fibers where Fiber modal noise is a significant factor, such as behind an adaptive optics system or on a small < 1 meter class telescope such as is being pursued by the MINERVA and LCOGT collaborations.r cube and visible camera. We summarize the practical details involved in the construction of the ber scrambler, and the mechanical agitation of the ber at the telescope. We present radial velocity measurements of a bright standard star taken with and without the ber scrambler to quantify the relative improvement in the obtainable blaze function stability, the line spread function stability, and the resulting radial velocity precision. We assess the feasibility of applying this illumination stabilization technique to the next generation of near-infrared spectrographs such as iSHELL on IRTF and an upgraded NIRSPEC at Keck. Our results may also be applied in the visible for smaller core diameter bers where ber modal noise is a signi cant factor, such as behind an adaptive optics system or on a small < 1 meter class telescope such as is being pursued by the MINERVA and LCOGT collaborations.
We have built and commissioned gas absorption cells for precision spectroscopic radial velocity measurements in the near-infrared in the H and K bands. We describe the construction and installation of three such cells filled with 13CH4, 12CH3D, and 14NH3 for the CSHELL spectrograph at the NASA Infrared Telescope Facility (IRTF). We have obtained their high-resolution laboratory Fourier Transform spectra, which can have other practical uses. We summarize the practical details involved in the construction of the three cells, and the thermal and mechanical control. In all cases, the construction of the cells is very affordable. We are carrying out a pilot survey with the 13CH4 methane gas cell on the CSHELL spectrograph at the IRTF to detect exoplanets around low mass and young stars. We discuss the current status of our survey, with the aim of photon-noise limited radial velocity precision. For adequately bright targets, we are able to probe a noise floor of 7 m/s with the gas cell with CSHELL at cassegrain focus. Our results demonstrate the feasibility of using a gas cell on the next generation of near-infrared spectrographs such as iSHELL on IRTF, iGRINS, and an upgraded NIRSPEC at Keck.
The New Worlds, New Horizons report released by the Astronomy and Astrophysics Decadal Survey Board in 2010
listed the Wide Field Infrared Survey Telescope (WFIRST) as the highest-priority large space mission for the coming
decade. This observatory will provide wide-field imaging and slitless spectroscopy at near infrared wavelengths. The
scientific goals are to obtain a statistical census of exoplanets using gravitational microlensing, measure the expansion
history of and the growth of structure in the Universe by multiple methods, and perform other astronomical surveys to be
selected through a guest observer program. A Science Definition Team has been established to assist NASA in the
development of a Design Reference Mission that accomplishes this diverse array of science programs with a single
observatory. In this paper we present the current WFIRST payload concept and the expected capabilities for planet
detection. The observatory, with science goals that are complimentary to the Kepler exoplanet transit mission, is
designed to complete the statistical census of planetary systems in the Galaxy, from habitable Earth-mass planets to free
floating planets, including analogs to all of the planets in our Solar System except Mercury. The exoplanet microlensing
survey will observe for 500 days spanning 5 years. This long temporal baseline will enable the determination of the
masses for most detected exoplanets down to 0.1 Earth masses.
SIM PlanetQuest is a space-borne Michelson interferometer with a nine meter baseline that will survey ~200 stars
within 30 parsecs for terrestrial mass planets. Ultra-precise astrometric observations will reveal the gravitational wobble
of the target star (due to a planetary companion) against an inertial frame of reference stars located within a 1.5 degree
radius. Here, we report the results of multiple Monte Carlo simulations which have modeled SIM's ability to detect and
determine the orbital parameters and masses of the terrestrial mass planets around its potential sample of target stars.
We find that SIM will detect 80% of the planets in the 60 star sample. Out of those planets SIM detects, we will be able
to estimate the masses of at least 50% of the planets to 30%. Whether SIM should observer 60 or 240 stars, will be
aided by the results of the Kepler mission which will provide statistics on the frequency of terrestrial-mass planets
around solar type stars. By determining the orbital phase of the planet, SIM will be able to assist TPF-C by telling it
when to look to ensure that the planet will be outside the TPF-C 62 mas inner working angle. Furthermore, the masses
determined by SIM will not suffer from the msini ambiguity inherent in radial velocity surveys.
We present diffraction limited 2-25 micrometers images, obtained with the W.M. Keck 10-m telescopes that spatially resolve the cool Galactic Center source IRS 21, an enigmatic object that has alluded classification. Modeled as a Gaussian, the azimuthally averaged intensity profile of IRS 21, an enigmatic object that has alluded classification. Modeled asa a Gaussian, the azimuthally averaged intensity profile of IRS 21 has a HWHM radius of 740 +/- 30 AU at 2.2 micrometers and an average HWHM radius of 1540 +/- 90 AU at mid-IR wavelength. These sizes along with its color temperature favor the hypothesis that IRS 21 is self-luminous rather than an externally heated dust clump. Based on the size alone, the remaining possible dust geometries are (1) an intrinsic inflow or outflow or (2) an extrinsic dust distribution, in which case IRS 21 could be simply embedded in the Northern Arm. A simple SED model of the IR photometry from the literature and our mid-IR images reveal that the near-IR radiation is scattered light from an unknown embedded source while the mid-IR radiation is the remaining re-radiated light. The agreement between the 2.2 micrometers polarization angle for IRS 21 and the 12.5 micrometers polarization angle at the position of IRS 21, the symmetric shape of its intensity profiles, as well as the similarity of the observed properties of all the Northern Arm sources, lead us to conclude that the scattering dust around IRS 21 is extrinsic to the central source and is associated with the Northern Arm.
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