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Mission Overview

Ultraviolet Imaging of the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey Fields (UVCANDELS)

 

Primary Investigator: Harry Teplitz

Full Team: See full team list.

HLSP Authors: 
Xin Wang, Laura Prichard, Anahita Alavi, Marc Rafelski, Norman Grogin, Anton Koekemoer, Ben Sunnquist, Vihang Mehta, Harry Teplitz

Released: 2022-06-13

Updated: 2024-10-22

Primary Reference(s): Wang et al. 2025

DOI: 10.17909/8s31-f778

Citations: See ADS Statistics

Read Me

Source Data:

Slideshow

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A CANDELS + UVCANDELS View of the EGS Field

Three-color image of a small region within the EGS field.

Composite of CANDELS and UVCANDELS images of a small region within the UVCANDELS image of the EGS field. The colors are: Blue: WFC3/F275W + ACS/F435W;  Green: ACS/F606W; Red: WFC3/F160W. The approximate size of the image on sky is 3.9 x 2.2 arcmin2.

UVCANDELS Coverage On-Sky

Map showing the location of UVCANDELS fields on the sky compared to other surveys in these areas.

Coverage of UVCANDELS pointings in the four fields.  Light blue and pink squares are from UVCANDELS.  Red dashed outlines are existing near-infrared survey coverage.

UVCANDELS

Circular logo for the UVCANDELS project: a field of galaxies on the sky with a white outline of the Hubble telescope on top.

Overview

UVCANDELS offers wide-area extragalactic UV imaging of four of the premier HST deep-wide survey fields defined by CANDELS. The program is motivated by an investigation of galaxy evolution during the epoch of vigorous star formation at 0.5 < z < 3 by:

  1. Using the high spatial resolution UV and Blue data (700 pc at z~1) to study the structural evolution of galaxies and create 2D maps of their star-formation history.
  2. Combining UVCANDELS with Herschel legacy data to trace the evolution of the dust content of moderate redshift (z < 1) galaxies.
  3. Probing the role of environment in the evolution of low-mass star-forming galaxies.
  4. Investigating the decay of star-formation in massive early-type galaxies and the role of minor mergers.
  5. Constraining the escape fraction of ionizing radiation from galaxies at z ~ 2.5 to better understand how star-forming galaxies reionized the Universe at z > 6.

UVCANDELS consists of WFC3/F275W imaging of four CANDELS fields (~430 sq. arcmin combined), reaching AB=27 for compact galaxies (SFR~0.2 Msun/yr at z=1), together with parallel ACS/F435W (AB>=28.0) imaging. For each field (GOODS-N, GOODS-S, COSMOS and EGS), we deliver image mosaics of the new F275W observations. The mosaics are made on both 60mas and 30mas pixel grids. The astrometry is aligned to the CANDELS optical 30mas mosaics (F814W for COSMOS and F606W for the rest), with a small relative offset (usually <0.15 pixel [<45 mas]).  The team also delivers new ACS/F435W images for the COSMOS and EGS Fields over the same area.  The F275W area of the GOODS fields falls within the original GOODS F435W coverage.

Photometric catalogs for the F275W and F435W imaging from UVCANDELS are provided separately for the individual fields. These catalogs were generated using SExtractor and list the photometry from two different techniques:

1.) CANDELS method [relevant columns labelled with "_OLD"]: hot+cold photometry measured using the isophotes defined on the F160W (H-band) image similar to how rest of the CANDELS photometry is performed (included for completeness and consistency with previous CANDELS catalogs); and

2.) IMPROVED method: new technique that uses isophotes defined on the F606W (V-band) image, which are better matched for the UV morphology of galaxies and then reconciled with the H-band isophotes to ensure photometry stays consistent with the rest of CANDELS (see Sun, L., et al. 2024 for more details).

The team highly recommends using the IMPROVED method photometry for both F275W and F435W.

Data Products

The image files have the following naming convention:

hlsp_uvcandels_hst_<ins>_<field>-<scale>_<filter>_v1.0_<type>.fits

where:

  • <ins> = Instrument used, one of "acs-wfc" or "wfc3-uvis".
  • <field> = Name of the field, one of "cosmos", "egs", "goodsn", or "goodss".
  • <scale> = Pixel grid for this image, in milliarcseconds, one of "30mas" or "60mas".
  • <filter> = Filter used, one of "f275w" or "f435w".
  • <type> = Type of image product, one of "sci", "wht", or "rms".

The photometric catalog files have the following naming convention:

hlsp_uvcandels_hst_<ins>_<field>_<filter>_v1.0_cat.fits

where:

  • <ins> = Instrument used, one of "acs-wfc" or "wfc3-uvis".
  • <field> = Name of the field, one of "cosmos", "egs", "goodsn", or "goodss".
  • <filter> = Filter used, one of "f275w" or "f435w".

The physical property catalogs have the following naming convention:

hlsp_uvcandels_multi_multi_<field>-<approach>_multi_v1.1_phys-cat.fits

where:

  • <field> = Name of the field, one of "cosmos", "egs", "goodsn", or "goodss". 
  • <approach> = Computational approach used to determine the physical properties contained within the catalog, one of "cigale" or "dbasis".

Data file types:

_sci.fits Science image.
_wht.fits Weight image, the inverse variance map created by AstroDrizzle.
_rms.fits

Noise map, after correcting for the correlated noise following Casertano et al. (2000).
_cat.fits Photometric catalog.
_phys-cat.fits Physical property catalog.
_photz-cat.fits Photometric redshift catalog.
_pdfz-cat.fits Photometric redshift probability distribution function catalog.

 

 

Data Access

 

You can download the mosaic FITS files using the links in the table below.

Field Pixel Grid F275W F435W
COSMOS 30mas RMS SCI WHT  RMS SCI WHT 
60mas RMS SCI WHT  RMS SCI WHT 
EGS 30mas RMS SCI WHT  RMS SCI WHT 
60mas RMS SCI WHT  RMS SCI WHT 
GOODS-N 30mas RMS SCI WHT   
60mas RMS SCI WHT   
GOODS-S 30mas RMS SCI WHT   
60mas RMS SCI WHT   

 

You can download the photometric (F275W and F435W) and physical property catalog files using the links in the table below.

F275W Catalogs F435W Catalogs Physical Property Catalogs (README)
COSMOS  COSMOS COSMOS-CIGALE, COSMOS-DBASIS
EGS EGS EGS-CIGALE, EGS-DBASIS
GOODS-N   GOODS-N-CIGALE, GOODS-N-DBASIS
GOODS-S   GOODS-S-CIGALE, GOODS-S-DBASIS

 

You can download the photometric redshift catalogs (README) here:  Photometric Redshift Catalog, Photometric Redshift Probability Distribution Catalog

Citations

Please remember to cite the appropriate paper(s) below and the DOI if you use these data in a published work. 

Note: These HLSP data products are licensed for use under CC BY 4.0.

References

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  • Sun et al. 2024

    The UV luminosity function at 0.6 < z < 1 from UVCANDELS

  • Mehta et al. 2024

    UVCANDELS: Catalogs of photometric redshifts and galaxy physical properties

  • Wang et al. 2025

    The Lyman Continuum Escape Fraction of Star-forming Galaxies at 2.4 ≲ z ≲ 3.0 from UVCANDELS