The 2012 Hubble Ultra Deep Field (UDF12): Observational overview

Anton M. Koekemoer, Richard S. Ellis, Ross J. McLure, James S. Dunlop, Brant E Robertson, Yoshiaki Ono, Matthew A. Schenker, Masami Ouchi, Rebecca A.A. Bowler, Alexander B. Rogers, Emma Curtis-Lake, Evan Schneider, Stephane Charlot, Daniel P. Stark, Steven R. Furlanetto, Michele Cirasuolo, V. Wild, T. Targett

Research output: Contribution to journalArticlepeer-review

134 Scopus citations


We present the 2012 Hubble Ultra Deep Field campaign (UDF12), a large 128 orbit Cycle 19 Hubble Space Telescope program aimed at extending previous Wide Field Camera 3 (WFC3)/IR observations of the UDF by quadrupling the exposure time in the F105W filter, imaging in an additional F140W filter, and extending the F160W exposure time by 50%, as well as adding an extremely deep parallel field with the Advanced Camera for Surveys (ACS) in the F814W filter with a total exposure time of 128 orbits. The principal scientific goal of this project is to determine whether galaxies reionized the universe; our observations are designed to provide a robust determination of the star formation density at z ≳ 8, improve measurements of the ultraviolet continuum slope at z ∼ 7-8, facilitate the construction of new samples of z ∼ 9-10 candidates, and enable the detection of sources up to z ∼ 12. For this project we committed to combining these and other WFC3/IR imaging observations of the UDF area into a single homogeneous dataset to provide the deepest near-infrared observations of the sky. In this paper we present the observational overview of the project and describe the procedures used in reducing the data as well as the final products that were produced. We present the details of several special procedures that we implemented to correct calibration issues in the data for both the WFC3/IR observations of the main UDF field and our deep 128 orbit ACS/WFC F814W parallel field image, including treatment for persistence, correction for time-variable sky backgrounds, and astrometric alignment to an accuracy of a few milliarcseconds. We release the full, combined mosaics comprising a single, unified set of mosaics of the UDF, providing the deepest near-infrared blank-field view of the universe currently achievable, reaching magnitudes as deep as AB ∼ 30 mag in the near-infrared, and yielding a legacy dataset on this field.

Original languageEnglish (US)
Article number3
JournalAstrophysical Journal, Supplement Series
Issue number1
StatePublished - Nov 2013


  • cosmology: observations
  • galaxies: high-redshift

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


Dive into the research topics of 'The 2012 Hubble Ultra Deep Field (UDF12): Observational overview'. Together they form a unique fingerprint.

Cite this