Data

This data release is based on our 2017 Astronomical Journal paper “The LCES HIRES/Keck Precision Radial Velocity Exoplanet Survey” (Butler, Vogt, Laughlin, Burt, Rivera, Tuomi, Teske, Arriagada, Diaz, Holden, Keiser). A copy of this paper can be found hereand in the “Planet” papers section of this website.

Spherical domes of the twin 10-meter telescopes are illuminated by the waxing moon as it rises above the summit of Mauna Kea. Keck I is in the foreground. At Keck II, 85 meters away, the Laser Guide Star system is in operation. The 12-watt sodium laser creates an artificial “star” 90 kilometers above the ground. Light from the guide star is analyzed by sophisticated optics at the telescope, allowing instant real-time correction for atmospheric turbulence and yielding precise celestial images that rival those from space telescopes. © 2007 Laurie Hatch, image and text

Spherical domes of the twin 10-meter telescopes are illuminated by the waxing moon as it rises above the summit of Mauna Kea. Keck I is in the foreground. At Keck II, 85 meters away, the Laser Guide Star system is in operation. The 12-watt sodium laser creates an artificial “star” 90 kilometers above the ground. Light from the guide star is analyzed by sophisticated optics at the telescope, allowing instant real-time correction for atmospheric turbulence and yielding precise celestial images that rival those from space telescopes. © 2007 Laurie Hatch, image and text

The paper contains 60,949 Doppler velocity measurements covering 1,624 stars taken over 20 years. These are typically the nearest and brightest F,G,K, and M dwarf stars that can be seen from Mauna Kea.

A brief history of the Keck/HIRES planet search can be found here.

Since we finalized the targets for the paper we have continued to mine the NASA/Keck data archive for new data. Starting with the raw images, we generate a logsheet, reduce the raw images to 1-D spectra, and measure Doppler velocities from the spectra, all with our proprietary software. Our latest update includes 64,480 Doppler velocity measurements of 1,699 stars. This updated data set is what we are releasing here.

The data is written as standard ascii (text) files designed to be plugged directly into the Systemic Planet Fitting package. A tutorial on running Systemic can be found here.

There are two data sets below. The first is the complete un-binned set of velocities (keck_vels). The second is the binned set of data (keck_vels_binned). We often take two or more consecutive observations of a star. We do  this for faint stars because we are starved for photons, but we don’t want our exposure times to go longer than  10 or 15 minutes. Longer exposures suffer from more cosmic ray hits, and they have a larger uncertainty in the photon-weighted mid-point of the observation. We also take multiple exposures of bright stars because they would saturate the CCD detector in less than 5 minutes. We prefer that the total exposure time on a star be 5 minutes or longer to average over the stellar seismology timescale. The “keck_vels_binned” file averages all the observations of a given star taken within 2 hours.

These are both “tar” files. Upon downloading them you will need to “un-tar” them. In a standard UNIX X-windows environment you can do this as follows:

UNIX> tar xvf keck_vels

As an example, we show the first 5 observations for HD10700. The columns are:

Julian DateVelocity (m/sUncertainty (m/s)S_valueHalphamedian photons per pixelexposure time (seconds)
2451755.047753.230.860.1859-1.0000021962530
2451755.047751.081.300.1799-1.0000010637012
2451757.05782-1.300.900.1766-1.0000021096321
2451792.95225-0.891.080.2050-1.0000014520612
2451793.93293-2.381.310.1927-1.00000902256

A -1 for S_value or Halpha indicates that a measurement could not be made. Halpha values begin in August 2004 when the CCD was upgraded.

We would appreciate it if any use of this data cites our paper (Butler, Vogt, Laughlin et al. 2017, AJ, in print)

Download files:

keck_vels.tar   keck_vels_binned.tar