The First Data Release of the KODIAQ Survey

TL;DR

The KODIAQ DR1 provides a comprehensive, high-resolution, publicly accessible dataset of quasar spectra for studying high-redshift galactic and circumgalactic ionized gas, especially OVI, from 170 quasars observed over eight years.

Contribution

This paper introduces the first data release of the KODIAQ survey, offering a large, uniformly processed high-resolution quasar spectral dataset for community use.

Findings

Contains 247 high-resolution spectra of 170 quasars.

Data covers a redshift range of 0.29 to 5.29.

Total exposure time is approximately 1.6 million seconds.

Abstract

We present and make publicly available the first data release (DR1) of the Keck Observatory Database of Ionized Absorption toward Quasars (KODIAQ) survey. The KODIAQ survey is aimed at studying galactic and circumgalactic gas in absorption at high-redshift, with a focus on highly-ionized gas traced by OVI, using the HIRES spectrograph on the Keck-I telescope. KODIAQ DR1 consists of a fully-reduced sample of 170 quasars at 0.29 < z_em < 5.29 observed with HIRES at high resolution (36,000 <= R <= 103,000) between 2004 and 2012. DR1 contains 247 spectra available in continuum normalized form, representing a sum total exposure time of ~1.6 megaseconds. These co-added spectra arise from a total of 567 individual exposures of quasars taken from the Keck Observatory Archive (KOA) in raw form and uniformly processed using a HIRES data reduction package made available through the XIDL distribution. DR1 is publicly available to the community, housed as a higher level science product at the KOA. We will provide future data releases that make further QSOs, including those with pre-2004 observations taken with the previous-generation HIRES detectors.