26 research outputs found
Towards Space-like Photometric Precision from the Ground with Beam-Shaping Diffusers
We demonstrate a path to hitherto unachievable differential photometric
precisions from the ground, both in the optical and near-infrared (NIR), using
custom-fabricated beam-shaping diffusers produced using specialized
nanofabrication techniques. Such diffusers mold the focal plane image of a star
into a broad and stable top-hat shape, minimizing photometric errors due to
non-uniform pixel response, atmospheric seeing effects, imperfect guiding, and
telescope-induced variable aberrations seen in defocusing. This PSF reshaping
significantly increases the achievable dynamic range of our observations,
increasing our observing efficiency and thus better averages over
scintillation. Diffusers work in both collimated and converging beams. We
present diffuser-assisted optical observations demonstrating
ppm precision in 30 minute bins on a nearby bright star
16-Cygni A (V=5.95) using the ARC 3.5m telescope---within a factor of 2
of Kepler's photometric precision on the same star. We also show a transit of
WASP-85-Ab (V=11.2) and TRES-3b (V=12.4), where the residuals bin down to
ppm in 30 minute bins for WASP-85-Ab---a factor of 4 of
the precision achieved by the K2 mission on this target---and to 101ppm for
TRES-3b. In the NIR, where diffusers may provide even more significant
improvements over the current state of the art, our preliminary tests have
demonstrated ppm precision for a star on the 200"
Hale Telescope. These photometric precisions match or surpass the expected
photometric precisions of TESS for the same magnitude range. This technology is
inexpensive, scalable, easily adaptable, and can have an important and
immediate impact on the observations of transits and secondary eclipses of
exoplanets.Comment: Accepted for publication in ApJ. 30 pages, 20 figure
Toward Space-like Photometric Precision from the Ground with Beam-shaping Diffusers
We demonstrate a path to hitherto unachievable differential photometric precisions from the ground, both in the optical and near-infrared (NIR), using custom-fabricated beam-shaping diffusers produced using specialized nanofabrication techniques. Such diffusers mold the focal plane image of a star into a broad and stable top-hat shape, minimizing photometric errors due to non-uniform pixel response, atmospheric seeing effects, imperfect guiding, and telescope-induced variable aberrations seen in defocusing. This PSF reshaping significantly increases the achievable dynamic range of our observations, increasing our observing efficiency and thus better averages over scintillation. Diffusers work in both collimated and converging beams. We present diffuser-assisted optical observations demonstrating 62_(-16)^(+26) ppm precision in 30 minute bins on a nearby bright star 16 Cygni A (V = 5.95) using the ARC 3.5 m telescope—within a factor of ~2 of Kepler's photometric precision on the same star. We also show a transit of WASP-85-Ab (V = 11.2) and TRES-3b (V = 12.4), where the residuals bin down to 180_(-41)^(+66) ppm in 30 minute bins for WASP-85-Ab—a factor of ~4 of the precision achieved by the K2 mission on this target—and to 101 ppm for TRES-3b. In the NIR, where diffusers may provide even more significant improvements over the current state of the art, our preliminary tests demonstrated 137_(-36)^(+64) ppm precision for a K_S = 10.8 star on the 200 inch Hale Telescope. These photometric precisions match or surpass the expected photometric precisions of TESS for the same magnitude range. This technology is inexpensive, scalable, easily adaptable, and can have an important and immediate impact on the observations of transits and secondary eclipses of exoplanets
A sub-Neptune sized planet transiting the M2.5-dwarf G 9-40: Validation with the Habitable-zone Planet Finder
We validate the discovery of a 2 Earth radii sub-Neptune-size planet around
the nearby high proper motion M2.5-dwarf G 9-40 (EPIC 212048748), using
high-precision near-infrared (NIR) radial velocity (RV) observations with the
Habitable-zone Planet Finder (HPF), precision diffuser-assisted ground-based
photometry with a custom narrow-band photometric filter, and adaptive optics
imaging. At a distance of , G 9-40b is the second closest
transiting planet discovered by K2 to date. The planet's large transit depth
(3500ppm), combined with the proximity and brightness of the host star at
NIR wavelengths (J=10, K=9.2) makes G 9-40b one of the most favorable
sub-Neptune-sized planet orbiting an M-dwarf for transmission spectroscopy with
JWST, ARIEL, and the upcoming Extremely Large Telescopes. The star is
relatively inactive with a rotation period of 29 days determined from the
K2 photometry. To estimate spectroscopic stellar parameters, we describe our
implementation of an empirical spectral matching algorithm using the
high-resolution NIR HPF spectra. Using this algorithm, we obtain an effective
temperature of K, and metallicity of
. Our RVs, when coupled with the orbital
parameters derived from the transit photometry, exclude planet masses above
with 99.7% confidence assuming a circular orbit. From its
radius, we predict a mass of and an RV
semi-amplitude of , making its mass
measurable with current RV facilities. We urge further RV follow-up
observations to precisely measure its mass, to enable precise transmission
spectroscopic measurements in the future.Comment: Accepted for publication in AJ, 22 pages, 15 figure
Sloan Digital Sky Survey IV: mapping the Milky Way, nearby galaxies, and the distant universe
We describe the Sloan Digital Sky Survey IV (SDSS-IV), a project encompassing three major spectroscopic programs. The Apache Point Observatory Galactic Evolution Experiment 2 (APOGEE-2) is observing hundreds of thousands of Milky Way stars at high resolution and high signal-to-noise ratios in the near-infrared. The Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey is obtaining spatially resolved spectroscopy for thousands of nearby galaxies (median ). The extended Baryon Oscillation Spectroscopic Survey (eBOSS) is mapping the galaxy, quasar, and neutral gas distributions between and 3.5 to constrain cosmology using baryon acoustic oscillations, redshift space distortions, and the shape of the power spectrum. Within eBOSS, we are conducting two major subprograms: the SPectroscopic IDentification of eROSITA Sources (SPIDERS), investigating X-ray AGNs and galaxies in X-ray clusters, and the Time Domain Spectroscopic Survey (TDSS), obtaining spectra of variable sources. All programs use the 2.5 m Sloan Foundation Telescope at the Apache Point Observatory; observations there began in Summer 2014. APOGEE-2 also operates a second near-infrared spectrograph at the 2.5 m du Pont Telescope at Las Campanas Observatory, with observations beginning in early 2017. Observations at both facilities are scheduled to continue through 2020. In keeping with previous SDSS policy, SDSS-IV provides regularly scheduled public data releases; the first one, Data Release 13, was made available in 2016 July
Sloan Digital Sky Survey IV: Mapping the Milky Way, Nearby Galaxies, and the Distant Universe
We describe the Sloan Digital Sky Survey IV (SDSS-IV), a project encompassing three major spectroscopic programs. The Apache Point Observatory Galactic Evolution Experiment 2 (APOGEE-2) is observing hundreds of thousands of Milky Way stars at high resolution and high signal-to-noise ratios in the near-infrared. The Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey is obtaining spatially resolved spectroscopy for thousands of nearby galaxies (median ). The extended Baryon Oscillation Spectroscopic Survey (eBOSS) is mapping the galaxy, quasar, and neutral gas distributions between and 3.5 to constrain cosmology using baryon acoustic oscillations, redshift space distortions, and the shape of the power spectrum. Within eBOSS, we are conducting two major subprograms: the SPectroscopic IDentification of eROSITA Sources (SPIDERS), investigating X-ray AGNs and galaxies in X-ray clusters, and the Time Domain Spectroscopic Survey (TDSS), obtaining spectra of variable sources. All programs use the 2.5 m Sloan Foundation Telescope at the Apache Point Observatory; observations there began in Summer 2014. APOGEE-2 also operates a second near-infrared spectrograph at the 2.5 m du Pont Telescope at Las Campanas Observatory, with observations beginning in early 2017. Observations at both facilities are scheduled to continue through 2020. In keeping with previous SDSS policy, SDSS-IV provides regularly scheduled public data releases; the first one, Data Release 13, was made available in 2016 July
Sloan Digital Sky Survey IV : mapping the Milky Way, nearby galaxies, and the distant universe
We describe the Sloan Digital Sky Survey IV (SDSS-IV), a project encompassing three major spectroscopic programs. The Apache Point Observatory Galactic Evolution Experiment 2 (APOGEE-2) is observing hundreds of thousands of Milky Way stars at high resolution and high signal-to-noise ratios in the near-infrared. The Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey is obtaining spatially resolved spectroscopy for thousands of nearby galaxies (median z ~ 0.03). The extended Baryon Oscillation Spectroscopic Survey (eBOSS) is mapping the galaxy, quasar, and neutral gas distributions between z ~ 0.6 and 3.5 to constrain cosmology using baryon acoustic oscillations, redshift space distortions, and the shape of the power spectrum. Within eBOSS, we are conducting two major subprograms: the SPectroscopic IDentification of eROSITA Sources (SPIDERS), investigating X-ray AGNs and galaxies in X-ray clusters, and the Time Domain Spectroscopic Survey (TDSS), obtaining spectra of variable sources. All programs use the 2.5 m Sloan Foundation Telescope at the Apache Point Observatory; observations there began in Summer 2014. APOGEE-2 also operates a second near-infrared spectrograph at the 2.5 m du Pont Telescope at Las Campanas Observatory, with observations beginning in early 2017. Observations at both facilities are scheduled to continue through 2020. In keeping with previous SDSS policy, SDSS-IV provides regularly scheduled public data releases; the first one, Data Release 13, was made available in 2016 July
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Sloan Digital Sky Survey IV: Mapping the Milky Way, Nearby Galaxies, and the Distant Universe
We describe the Sloan Digital Sky Survey IV (SDSS-IV), a project encompassing
three major spectroscopic programs. The Apache Point Observatory Galactic
Evolution Experiment 2 (APOGEE-2) is observing hundreds of thousands of Milky
Way stars at high resolution and high signal-to-noise ratio in the
near-infrared. The Mapping Nearby Galaxies at Apache Point Observatory (MaNGA)
survey is obtaining spatially-resolved spectroscopy for thousands of nearby
galaxies (median redshift of z = 0.03). The extended Baryon Oscillation
Spectroscopic Survey (eBOSS) is mapping the galaxy, quasar, and neutral gas
distributions between redshifts z = 0.6 and 3.5 to constrain cosmology using
baryon acoustic oscillations, redshift space distortions, and the shape of the
power spectrum. Within eBOSS, we are conducting two major subprograms: the
SPectroscopic IDentification of eROSITA Sources (SPIDERS), investigating X-ray
AGN and galaxies in X-ray clusters, and the Time Domain Spectroscopic Survey
(TDSS), obtaining spectra of variable sources. All programs use the 2.5-meter
Sloan Foundation Telescope at Apache Point Observatory; observations there
began in Summer 2014. APOGEE-2 also operates a second near-infrared
spectrograph at the 2.5-meter du Pont Telescope at Las Campanas Observatory,
with observations beginning in early 2017. Observations at both facilities are
scheduled to continue through 2020. In keeping with previous SDSS policy,
SDSS-IV provides regularly scheduled public data releases; the first one, Data
Release 13, was made available in July 2016
The Eleventh and Twelfth Data Releases of the Sloan Digital Sky Survey: Final Data from SDSS-III
The third generation of the Sloan Digital Sky Survey (SDSS-III) took data from 2008 to 2014 using the original SDSS wide-field imager, the original and an upgraded multi-object fiber-fed optical spectrograph, a new near-infrared high-resolution spectrograph, and a novel optical interferometer. All of the data from SDSS-III are now made public. In particular, this paper describes Data Release 11 (DR11) including all data acquired through 2013 July, and Data Release 12 (DR12) adding data acquired through 2014 July (including all data included in previous data releases), marking the end of SDSS-III observing. Relative to our previous public release (DR10), DR12 adds one million new spectra of galaxies and quasars from the Baryon Oscillation Spectroscopic Survey (BOSS) over an additional 3000 deg2 of sky, more than triples the number of H-band spectra of stars as part of the Apache Point Observatory (APO) Galactic Evolution Experiment (APOGEE), and includes repeated accurate radial velocity measurements of 5500 stars from the Multi-object APO Radial Velocity Exoplanet Large-area Survey (MARVELS). The APOGEE outputs now include the measured abundances of 15 different elements for each star. In total, SDSS-III added 5200 deg2 of ugriz imaging; 155,520 spectra of 138,099 stars as part of the Sloan Exploration of Galactic Understanding and Evolution 2 (SEGUE-2) survey; 2,497,484 BOSS spectra of 1,372,737 galaxies, 294,512 quasars, and 247,216 stars over 9376 deg2; 618,080 APOGEE spectra of 156,593 stars; and 197,040 MARVELS spectra of 5513 stars. Since its first light in 1998, SDSS has imaged over 1/3 of the Celestial sphere in five bands and obtained over five million astronomical spectra. \ua9 2015. The American Astronomical Society