Keywords: Astronomical Observatories, Charge Coupled Devices, Data Acquisition, Halley'S Comet, Pixels, Low Noise, Unix (Operating System), Voltage Regulators, Waveforms

Keywords: Charge Coupled Devices, High Speed, Photometers, Stellar Spectrophotometry, Atmospheric Attenuation, Data Reduction, Image Analysis, Real Time Operation, Signal To Noise Ratios, Spectrum Analysis

Keywords: Position Errors, Reflecting Telescopes, Rollers, Sliding Friction, Software Tools, Tracking (Position), Alignment, Antifriction Bearings, Charge Coupled Devices, Synchronous Satellites

Keywords: Astronomical Spectroscopy, Computer Aided Design, Optical Fibers, Optimization, Computer Programs, Spectral Correlation

Keywords: Echelle Gratings, Illuminating, Image Analysis, Light Scattering, Spectrographs, Background Radiation, Correction, Mathematical Models

Greisen & Calabretta describe a generalized method for specifying the coordinates of FITS data samples. Following that general method, Calabretta & Greisen describe detailed conventions for defining celestial coordinates as they are projected onto a two-dimensional plane. The present paper extends the discussion to the spectral coordinates of wavelength, frequency, and velocity. World coordinate functions are defined for spectral axes sampled linearly in wavelength, frequency, or velocity, linearly in the logarithm of wavelength or frequency, as projected by ideal dispersing elements, and as specified by a lookup table.

Keywords: methods: data analysis, techniques: image processing, techniques: radial velocities, techniques: spectroscopic, astronomical data bases: miscellaneous

Keywords: methods: data analysis, methods: observational

Before atomic timekeeping, clocks were set to the skies. But starting in 1972, radio signals began broadcasting atomic seconds and leap seconds have occasionally been added to that stream of atomic seconds to keep the signals synchronized with the actual rotation of Earth. Such adjustments were considered necessary because Earth's rotation is less regular than atomic timekeeping. In January 2012, a United Nations-affiliated organization could permanently break this link by redefining Coordinated Universal Time. To understand the importance of this potential change, it's important to understand the history of human timekeeping.

Keywords: astro-ph.IM, physics.hist-ph, physics.pop-ph

On October 5 and October 6, 2011, the Colloquium on the Decoupling Civil Timekeeping from Earth Rotation was hosted in Exton, Pennsylvania by Analytical Graphics, Inc. (AGI). This paper highlights various technical perspectives offered through these proceedings, including expressions of concern and various recommendations offered by colloquium participants.

Keywords: astro-ph.IM, physics.soc-ph

The Long Now Foundation is building a mechanical clock that is designed to keep time for the next 10,000 years. The clock maintains its long-term accuracy by synchronizing to the Sun. The 10,000-Year Clock keeps track of five different types of time: Pendulum Time, Uncorrected Solar Time, Corrected Solar Time, Displayed Solar Time and Orrery Time. Pendulum Time is generated from the mechanical pendulum and adjusted according to the equation of time to produce Uncorrected Solar Time, which is in turn mechanically corrected by the Sun to create Corrected Solar Time. Displayed Solar Time advances each time the clock is wound, at which point it catches up with Corrected Solar Time. The clock uses Displayed Solar Time to compute various time indicators to be displayed, including the positions of the Sun, and Gregorian calendar date. Orrery Time is a better approximation of Dynamical Time, used to compute positions of the Moon, planets and stars and the phase of the Moon. This paper describes how the clock reckons time over the 10,000-year design lifetime, in particular how it reconciles the approximate Dynamical Time generated by its mechanical pendulum with the unpredictable rotation of the Earth.

Keywords: astro-ph.IM, physics.hist-ph

Keywords: remote observing, observation scheduling

The Automated Planet Finder (APF) is a facility purpose-built for the discovery and characterization of extrasolar planets through high-cadence Doppler velocimetry of the reflex barycentric accelerations of their host stars. Located atop Mt. Hamilton, the APF facility consists of a 2.4-m telescope and its Levy spectrometer, an optical echelle spectrometer optimized for precision Doppler velocimetry. APF features a fixed format spectral range from 374 nm - 970 nm, and delivers a "Throughput" (resolution * slit width product) of 114,000 arc-seconds, with spectral resolutions up to 150,000. Overall system efficiency (fraction of photons incident on the primary mirror that are detected by the science CCD) on blaze at 560 nm in planet-hunting mode is 15%. First-light tests on the RV standard stars HD 185144 and HD 9407 demonstrate sub-meter per second precision (RMS per observation) held over a 3-month period. This paper reviews the basic features of the telescope, dome, and spectrometer, and gives a brief summary of first-light performance.

Keywords: astro-ph.IM