19 research outputs found
The Fourteenth Data Release of the Sloan Digital Sky Survey: First Spectroscopic Data from the Extended Baryon Oscillation Spectroscopic Survey and from the Second Phase of the Apache Point Observatory Galactic Evolution Experiment
The fourth generation of the Sloan Digital Sky Survey (SDSS-IV) has been in operation since 2014 July. This paper describes the second data release from this phase, and the 14th from SDSS overall (making this Data Release Fourteen or DR14). This release makes the data taken by SDSS-IV in its first two years of operation (2014–2016 July) public. Like all previous SDSS releases, DR14 is cumulative, including the most recent reductions and calibrations of all data taken by SDSS since the first phase began operations in 2000. New in DR14 is the first public release of data from the extended Baryon Oscillation Spectroscopic Survey; the first data from the second phase of the Apache Point Observatory (APO) Galactic Evolution Experiment (APOGEE-2), including stellar parameter estimates from an innovative data-driven machine-learning algorithm known as "The Cannon"; and almost twice as many data cubes from the Mapping Nearby Galaxies at APO (MaNGA) survey as were in the previous release (N = 2812 in total). This paper describes the location and format of the publicly available data from the SDSS-IV surveys. We provide references to the important technical papers describing how these data have been taken (both targeting and observation details) and processed for scientific use. The SDSS web site (www.sdss.org) has been updated for this release and provides links to data downloads, as well as tutorials and examples of data use. SDSS-IV is planning to continue to collect astronomical data until 2020 and will be followed by SDSS-V
Unveiling acoustic physics of the CMB using nonparametric estimation of the temperature angular power spectrum for Planck
A Model-independent Determination of the Hubble Constant from Lensed Quasars and Supernovae Using Gaussian Process Regression
Parameter discordance in Planck CMB and low-redshift measurements: projection in the primordial power spectrum
Strong Lens Time Delay Challenge: II. Results of TDC1
We present the results of the first strong lens time delay challenge. The
motivation, experimental design, and entry level challenge are described in a
companion paper. This paper presents the main challenge, TDC1, which consisted
of analyzing thousands of simulated light curves blindly. The observational
properties of the light curves cover the range in quality obtained for current
targeted efforts (e.g.,~COSMOGRAIL) and expected from future synoptic surveys
(e.g.,~LSST), and include simulated systematic errors. \nteamsA\ teams
participated in TDC1, submitting results from \nmethods\ different method
variants. After a describing each method, we compute and analyze basic
statistics measuring accuracy (or bias) , goodness of fit ,
precision , and success rate . For some methods we identify outliers as
an important issue. Other methods show that outliers can be controlled via
visual inspection or conservative quality control. Several methods are
competitive, i.e., give , , and , with some of
the methods already reaching sub-percent accuracy. The fraction of light curves
yielding a time delay measurement is typically in the range 20--40\%. It
depends strongly on the quality of the data: COSMOGRAIL-quality cadence and
light curve lengths yield significantly higher than does sparser sampling.
Taking the results of TDC1 at face value, we estimate that LSST should provide
around 400 robust time-delay measurements, each with and ,
comparable to current lens modeling uncertainties. In terms of observing
strategies, we find that and depend mostly on season length, while P
depends mostly on cadence and campaign duration.Comment: referee's comments incorporated; to appear in Ap