The Star Formation Across Cosmic Time (SFACT) Survey. I. Survey Description and Early Results from a New Narrowband Emission-line Galaxy Survey

We introduce the Star Formation Across Cosmic Time (SFACT) survey. SFACT is a new narrowband survey for emission-line galaxies (ELGs) and QSOs being carried out using the wide-field imager on the WIYN 3.5 m telescope. Because of the superior depth and excellent image quality afforded by WIYN, we routinely detect ELGs to r = 25.0. Our survey observations are made using three custom narrowband filters centered on 6590 Å, 6950 Å, and 7460 Å. Due to the sensitivity of the survey, we are able to simultaneously detect sources via a number of different emission lines over a wide range of redshifts. The principal lines detected in SFACT are Hα (redshifts up to 0.144), [O iii]λ5007 (redshifts up to 0.500), and [O ii]λ3727 (redshifts up to 1.015). In this paper, we detail the properties of the survey as well as present initial results obtained by analyzing our three pilot-study fields. These fields have yielded a total of 533 ELG candidates in an area of 1.50 deg2 (surface density of 355 ELGs deg−2). Follow-up spectra for a subset of the ELG candidates are also presented. One of the key attributes of the SFACT survey is that the ELGs are detected in discrete redshift windows that will allow us to robustly quantify the properties of the star-forming and active galactic nucleus populations as a function of redshift to z = 1 and beyond. The planned acquisition of additional narrowband filters will allow us to expand our survey to substantially higher redshifts.