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The 132 orbits of HDUV data were obtained in 42 independent visits between 2014 November 25 and 2015 November 16. In GOODS-S, these visits were composed of 4 or 5 full-orbit exposures in either F275W or F336W. The exposure time of these images was ~2600-2800 s. In GOODS-N, all visits made use of the CVZ. Thus to reach an equivalent 4-orbit exposure, only 2 actual orbits were required for each filter (at the expense of an increased background during the bright part of the orbit).

Data Processing

A special pipeline for the reduction of these data was written based on previous WFC3 and ACS data reduction pipelines developed by our team and used, e.g., for the public image release of the XDF and the HLF (Illingworth et al. 2013, 2016). The pipeline is written in python and makes heavy use of the drizzlepac software package developed by STScI, which includes the basic processing steps required for HST data reduction.

CTE Correction

The WFC3/UVIS images need to be corrected for charge transfer (in)efficiencies (CTE). A pixel-based correction method is provided by STScI, which is applied directly to the raw images.

Sky Darks

The WFC3/UVIS images were found to show significant structure in their dark images, which clearly shows up when combining images at a depth of several orbits as available here. In particular, the combined WFC3/UVIS images exhibit a significant "striping" along the readout direction when using the standard, non-CTE corrected dark frames (that were available at the time of these observations). To remedy this, a sky dark was computed based on all the exposures for each filter, which was then subtracted from each individual exposure. This procedure resulted in very flat and uniform images.

Note that the spirit of the sky dark procedure is similar to the use of the newly developed "self-calibration" by STScI (see Anderson & Ogaz 2014), which constructs delta-darks to be subtracted from each image.

Image Alignment

Image alignment was performed relative to the F435W images from the GOODS dataset. The HDUV survey was designed to allow for straightforward alignment by obtaining several images of the same filter in a given visit. The relative positions of exposures within a visit are accurate enough that they can easily be combined and cosmic ray cleaned, before a global shift is determined for each visit.

The CANDELS UV images required additional steps for alignment, since they were taken exclusively in the bright part of each CVZ orbit, with only one F275W image (of about 1500 s) per visit. A simple visit-by-visit alignment strategy is thus not applicable. However, the CANDELS survey obtained a short ~400 s long-pass F350LP image in each visit immediately before the F275W exposure. Those images contain enough high-S/N sources for an accurate alignment and were used to compute relative shifts that were applied to the F275W exposures.

Pixel Grid

The processed images were drizzled to the same 60mas pixel grid as the 3D-HST images (available here), to enable the most efficient use of these data. The images have dimensions of 17500×19700 pixels in GOODS-S and 20480×20480 pixels in GOODS-N.

Programs Used

The table below lists all the programs from which data have been included in this image release.

Program ID HST Cycle Program Title
13872 22 The GOODS UV Legacy Fields: A Full Census of Faint Star-Forming Galaxies at z~0.5-2
12445 20 Cosmic Assembly Near-IR Deep Extragalactic Legacy Survey -- GOODS-North Field, Late Visits of SNe Search
12534 19 The Panchromatic Hubble Ultra Deep Field: Ultraviolet Coverage
12444 19 Cosmic Assembly Near-IR Deep Extragalactic Legacy Survey -- GOODS-North Field, Middle Visits of SNe Search

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Imaging Data


This HDUV data release includes the final drizzled images of the completed HST dataset as well as a source catalog in both fields. In particular, the dataset covers 6 pointings of WFC3/UVIS images in the GOODS-S and 8 pointings in GOODS-N at full 8-10 orbit depth for a total coverage of almost exactly 100 arcmin2. The GOODS-N images also include a shallower component around the primary pointings which was taken as part of the CANDELS survey.

The images are drizzled to the same pixel frame as the GOODS/CANDELS images released by the 3D-HST team in order to make multi-wavelength analyses by the community particularly easy. The data release described here includes the F275W images from the CANDELS survey in GOODS-N as well as the UVUDF in GOODS-S. The UVUDF was matched to the HDUV pixel grid using swarp and then combined with the data using inverse variance weighting in the overlap regions.


The file names contain all the necessary information on the passband (F275W, F336W), the pixel scale (60mas), the data release version (v1.0) and the image type (science image or rms map). For example, the FITS file containing the F336W science data from GOODS-North is called:


HST Data Download

The following table provides links to the science and rms images for download.

Interactive Displays

Interactive displays are available for each image.

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Magnitude Zero Points

The pixel values of the science images report the flux count rate calibrated in electron/second. The zero points to convert the count rate into AB magnitudes for the two fields are listed below. They include a correction for Galactic dust based on Schlafly & Finkbeiner (2011): E(B-V) = 0.0069 mag and 0.0105 mag for GOODS-South and North, respectively (see here).

Filter Zero Point ABMAG GOODS-S Zero Point ABMAG GOODS-N
F275W 24.087 24.065
F336W 24.633 24.615

RMS Maps

The rms maps are generated based on the AstroDrizzle weight maps and provide the root-mean-square noise fluctuations per pixel. The rms maps have been corrected for correlated pixel noise that is introduced during the drizzle process, as discussed in Casertano et al. (2000) (see especially Section 3.5 and Appendix A).


The image depths are derived directly from the images by placing a large number (10,000 per field) of circular apertures in empty sky regions of the HDUV images and measuring their enclosed flux. The dispersion of these flux histograms represents the most accurate, empirical measurement of the average image depth. Using 0.4 arcsec diameter apertures, we measure 5sigma depths of 27.5 and 27.9 in the two filters F275W and F336W, respectively, averaged over the full HDUV survey footprint (see also table above).

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Source Catalogs


Preliminary photometric catalogs spanning the HDUV survey footprint are provided in this release. The catalogs include photometry, photometric redshifts, and stellar population properties. They are built on the catalogs of the GOODS fields that were released by the 3D-HST survey team (described in Skelton et al. (2014) and available here). The UV photometry is consistently derived to match the 3D-HST photometry, following the same methodology and detection images used in Skelton et al. (2014) and summarized here.

Catalog Creation


Catalogs are derived from PSF-matched images. To this end, the HDUV point-spread functions are derived for each band separately using the software PSFex (Bertin 2011), and a kernel is derived to match these to the lowest resolution HST image in the GOODS/CANDELS fields, i.e. the F160W band. Following Skelton et al. (2014), sources are detected at near-infrared wavelengths based on a noise-optimized combination of the WFC3/IR F125W, F140W and F160W images using SExtractor (Bertin & Arnouts 1996). Photometry is measured in circular apertures of 0.7 arcsec diameter on the PSF-matched images, and is corrected to total fluxes using the same correction factor as employed by the 3D-HST catalog.

The source IDs are matched to the 3D-HST source catalogs in the two GOODS/CANDELS fields, given that they are based on the same detection image. The catalogs are trimmed to the HDUV survey footprint (including the UVUDF in GOODS-S), however. To make these catalogs most useful, the flux columns of the 3D-HST survey catalogs are repeated as well. In total, the catalogs thus contain 2 new filter fluxes (F275W and F336W) and their associated flux errors, plus 40 and 22 HST, Spitzer/IRAC, and ground-based filter fluxes in GOODS-S and -N, respectively.

Photometric Redshifts and Physical Parameters

Photometric redshifts and physical parameters are derived based on SED fitting to the full filter fluxes available for each source using the same template set and procedures as the 3D-HST catalogs. In particular, photometric redshifts are based on the code EAZY (Brammer et al. 2008) and physical parameters are derived using FAST (Kriek et al. 2009) using a template set from Bruzual & Charlot (2003). For more information on these procedures, see Skelton et al. (2014).

Catalog Download

The source catalogs can be downloaded using the links in the following table. A short readme file is provided to explain the different columns.

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If you use these data in work that you publish, we'd appreciate it if you could acknowledge your use by including the following citation:

Oesch et al. 2018, ApJS, accepted

The team members involved in the HDUV survey are: P. Oesch, M. Montes, N. Reddy, R. J. Bouwens, G. D. Illingworth, D. Magee, H. Atek, C. M. Carollo, A. Cibinel, M. Franx, B. Holden, I. Labbe, E. J. Nelson, C. C. Steidel, P. G. van Dokkum, L. Morselli, R. P. Naidu, S. Wilkins.

For questions and more information about the data reduction pipeline, please contact:

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  • Anderson & Ogaz 2014, ISR 14-03
  • Bertin & Arnouts 1996 A&AS, 117, 393
  • Bertin 2011, ASPC, 442, 435
  • Brammer et al. 2008, ApJ, 686, 1503
  • Bruzual & Charlot 2003, MNRAS, 344, 1000
  • Casertano et al. 2000, AJ, 120, 2747
  • Grogin et al. 2011, ApJS, 197, 35
  • Illingworth et al. 2013, ApJS, 209, 6
  • Illingworth et al. 2016, arXiv:1606.00841
  • Kriek et al. 2009, ApJL, 705, 71
  • Oesch et al. 2018, ApJS, accepted
  • Rafelski et al. 2015, AJ, 150, 31
  • Skelton et al. 2014, ApJS, 214, 24
  • Teplitz et al. 2013, AJ, 146, 159

Last update: 2018-05-22