Abstract
OzDES is a five-year, 100-night, spectroscopic survey on the Anglo-Australian Telescope, whose primary aim is to measure redshifts of approximately 2,500 Type Ia supernovae host galaxies over the redshift range 0.1 < z < 1.2, and derive reverberation-mapped black hole masses for approximately 500 active galactic nuclei and quasars over 0.3 < z < 4.5. This treasure trove of data forms a major part of the spectroscopic follow-up for the Dark Energy Survey for which we are also targeting cluster galaxies, radio galaxies, strong lenses, and unidentified transients, as well as measuring luminous red galaxies and emission line galaxies to help calibrate photometric redshifts. Here we present an overview of the OzDES program and our first-year results. Between Dec 2012 and Dec 2013, we observed over 10,000 objects and measured more than 6,000 redshifts. Our strategy of retargeting faint objects across many observing runs has allowed us to measure redshifts for galaxies as faint as m_r=25 mag. We outline our target selection and observing strategy, quantify the redshift success rate for different types of targets, and discuss the implications for our main science goals. Finally, we highlight a few interesting objects as examples of the fortuitous yet not totally unexpected discoveries that can come from such a large spectroscopic survey.
Highlights
The Australian Dark Energy Survey (OzDES)1 has been designed to provide efficient spectroscopic follow-up of targets identified from imaging by the Dark Energy Survey (DES; Flaugher 2005; Diehl et al 2014)
The Australian Telescope (AAT) and CTIO 4m are similar in several respects — both are 4m class telescopes that were commissioned in 1974 and both have recently been rejuvenated with powerful new instrumentation: in the case of CTIO it is the 570 mega-pixel Dark Energy Camera (DECam; Diehl et al 2012; Flaugher et al 2012), while on the AAT it is the new efficient AAOmega spectrograph (Smith et al 2004) coupled with the Two Degree Field (2dF) 400-fibre multi-object fibre-positioning system (Lewis et al 2002)
We organise the paper as follows: In § 2 we summarise our science goals and in § 3 we present the operational details that were current at the end of Y1, highlighting what was modified to improve the efficiency of the survey for Y2
Summary
The Australian Dark Energy Survey (OzDES) has been designed to provide efficient spectroscopic follow-up of targets identified from imaging by the Dark Energy Survey (DES; Flaugher 2005; Diehl et al 2014). The DES program consists of a wide-field survey covering 5000 square degrees, as well as a rolling survey of ten fields that cover a total of 30 square degrees (Diehl et al 2014). These ten fields (see Table 1 for the sky coordinates) are targeted repeatedly over the course of the survey with a cadence of approximately 6 days in order to find transient objects, such as supernovae, and monitor variable objects, such as AGN. OzDES repeatedly targets these ten fields, Field Name E1 E2 S1 S2 C1 C2 C3 (deep) X1 X2 X3 (deep)
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