Overview

This describes the V2.5 version data release of the Hubble Legacy Fields (HLF) project for the GOODS-North and GOODS-South regions from the HST archival programs AR-13252 and AR-15027. The V2.5 version of the HLF dataset provides WFC3/UV, ACS/WFC and WFC3/IR source catalogs and image mosaics covering a 25 x 25 arcminute area plus (smaller) cutouts of four deep areas in the GOODS-South field and image mosaics covering a 20.5 x 20.5 arcminute area in the GOODS-North field. All the data covering the original HUDF field within the GOODS-South area were previously released as a high level science product as the eXtreme Deep Field (XDF — sometimes referred to as the XDF/HUDF field).

HLF Release: The release combines exposures from Hubble's two main cameras, the Advanced Camera for Surveys Wide Field Channel (ACS/WFC) and the Wide Field Camera 3 (WFC3), including data from both the infrared channel (WFC3/IR) and the UV/visible channel (WFC3/UVIS). These data were taken over more than a decade between mid-2002 to the end of 2020. The HLF includes essentially all the near-uv (WFC3/UV F225W, F275W, F336W), optical (ACS/WFC F435W, F606W, F775W, F814W and F850LP filters) and infrared (WFC3/IR F098M, F105W, F125W, F140W and F160W filters) filters. The HLF includes data taken by Hubble over the original CDF-North/South region including the GOODS-N/S, CANDELS, ERS, the Extended CDF-S (ECDF-S), numerous SNe followup programs, and many other programs. Given that this dataset combines all images in the archive on the ECDF-S to date from numerous different programs, the HST AR-13252 and AR-15027 proposals identified the product under a single global name "Hubble Legacy Fields".

Astrometric Frame: A particularly challenging aspect, given the large area, was to establish a robust astrometric framework. A global astrometric solution was bootstrapped from the smaller datasets. All the HLF image mosaics have been produced using a coordinate grid tied to an absolute Gaia DR2 reference frame. We also provide an alternate coordinate system using the same tangent point as the original GOODS-N/S datasets.

Exposure Time: The total HST on-target exposure time of all the data incorporated in the HLF-GOODS-N is 3.6 Msec and 6.4 MSec in the HLF-GOODS-S. The HLF-GOODS-N and HLF-GOODS-S dataset are derived from 5817 and 7491 exposures, respectively, and taken from 33 different HST programs. This on-target exposure time is equivalent to that of about 4181 orbits (assuming that the exposure in a typical orbit is 2400s). This total exposure corresponds to over ~120% of a full HST resource cycle! The HLF dataset also includes four very deep pointings from observations made in parallel when HUDF was primary (the HLF-HUDFP1-4 parallel fields). Unlike the XDF/HUDF, these parallel fields have a smaller set of filters and have varying depths, but still constitute a resource of unusually deep fields.

Catalog: A catalog of all the sources in the HLF GOODS-South dataset, with photometry for sources in each of the 13 filters, is also made available with this release. The photometric catalog includes 103,098 objects, selected in either of two near-IR filters (F850LP and F160W). The photometric results are measured in 0.7′′ diameter apertures and corrected to total fluxes based on the F160W curve of growth.

HLF Team: The HLF Team is The HLF Team is Garth Illingworth, Daniel Magee, Rychard Bouwens, Pascal Oesch, Kate Whitaker, Ivo Labbe, Pieter van Dokkum, Mauro Stefanon, Bradford Holden, Marijn Franx, and Valentino Gonzalez. The catalog was led by Katherine Whitaker. Please credit Illingworth et al 2019 when using the HLF HSLP data and products, and Whitaker et al 2019 for the catalog. The UVUDF dataset was graciously provided by Harry Teplitz, Anton Koekemoer, Marc Rafelski, Norman Grogin and the UVUDF Team. If you use any of the HLF-GOODS-S UV data, please also cite Teplitz et al. 2013 and Rafelski et al. 2015.

What's new in V2.5

The HLF V2.5 includes the release of the HLF-GOODS-N dataset. The HLF-GOODS-N comprises 5817 exposures taken over nearly 18 years with WFC3/UVIS, ACS/WFC and WFC3/IR totaling 3.6 million seconds. This is 1516 orbits of data or about 50% of a full one-year Cycle. Note that a substantial fraction (~59%) of these data have never been available as a high-level data product. HLF-GOODS-N dataset incorporates 11 filters consisting of two WFC3/UVIS, five ACS/WFC and four WFC3/IR filters

What's in V2.0

A major change from the HLF-GOODS-S V1.5 data release to the V2.0 release is the inclusion of three UV datasets. These sets constitute a substantial body of UV data, totaling 280 orbits of HST WFC3/UVIS imaging, or about 0.5 Msec of data. The three UV datasets are the Early Release Science (ERS) observations (Windhorst et al 2011), the UltraViolet Ultra-Deep Field (UVUDF) dataset (Teplitz et al. 2013, Rafelski et al. 2015) and the Hubble Deep UltraViolet (HDUV) legacy dataset (Oesch et al 2018, see also Vanzella et al 2016). These datasets were updated and astrometrically matched to the V1.5/V2.0 release of the HLF-GOODS-S. The ERS dataset required a full reprocessing since that has not be available in processed form on MAST. Thus the HLF provides for the first time the release of the WFC3/UV 2009 ERS dataset as a HLSP.

The steps that were taken to assemble the HST UV data along with the HST optical and near-IR data are described in the paper that discusses the assembly of the HLF-GOODS-S dataset (Illingworth et al 2021).

As noted above the V2.0 release now includes a catalog of over 100,000 sources with photometry in all 13 filters (or those sources for which the S/N was adequate for inclusion). See Whitaker et al 2019.

Additionally, we have organized the ACS/WFC and WFC3/IR data into twelve one year epochs from the fourteen years of observations on the ECDF-S, starting with the first epoch from May 2002 to April 2003 (there were two years where no significant additional data was obtained due to ACS/WFC failure in January 2007). See hlf_goodss_v2_epoch_by_filter.pdf.