The CANDELS Multi-Cycle Treasury Program

The Cosmic Assembly Near-IR Deep Extragalactic Legacy Survey, CANDELS (Grogin et al. 2011; Koekemoer et al. 2011), PI: S. Faber, Co-PI, H. Ferguson, is designed to document the first third of galactic evolution from z = 8 to 1.5 via deep imaging of more than 250,000 galaxies with WFC3/IR and ACS. It will also discover and characterize Type Ia SNe beyond z > 1.5 and establish their accuracy as standard candles for cosmology.

The survey targets five premier multi-wavelength sky regions; each has multi-wavelength data from Spitzer and other facilities plus extensive spectroscopy of the brighter galaxies. The use of five widely separated fields mitigates cosmic variance and yields statistically robust and complete samples of galaxies down to 109 solar masses out to redshift z ~ 8.

The program incorporates a "Wide" imaging survey to 2-orbit J+H depth over 720 sq. arcmin in the COSMOS, EGS, and UDS fields. It also includes a "Deep" imaging survey to ~12 orbit Y+J+H depth in the two GOODS fields, tiling ~60 sq. arcmin in each field. In combination with ultra-deep imaging from the Hubble Ultradeep Field program (GO 11563), the result is a three-tiered strategy that effciently samples both bright/rare and faint/common extragalactic objects.

By imaging each field region at least twice on two visits separated by ~60 days, the program also carries out an extensive search for high-redshift Type Ia SNe beyond z > 1.5. Iin addition, ultraviolet "daytime" UVIS exposures in GOODS-N exploit the unique CVZ opportunity in that field.

Released Products	Wide: Multidrizzled mosaics from each epoch in each filter; ultimately summed mosaics from both CANDELS epochs. Deep: Multidrizzled mosaics from each epoch in each filter; ultimately summed mosaics including all CANDELS data from previous epochs. UVIS: for the first epoch, single-drizzled tiles are available from the archive (one exposure per tile with no CR rejection); summed mosaics with CR rejection for subsequent epochs. ch, single-drizzled tiles are available from the archive (one exposure per tile with no CR rejection); ultimately summed mosaics with CR rejection from multiple epochs.
Version Definition	v0.5 represents our best-effort calibration at that time, including bias-stripe and CTE corrections for ACS, but no corrections for WFC3/IR persistence. v1.0 uses more mature instrument calibration files, improved astrometry where necessary, and persistence corrections for WFC3/IR where applicable.
Release Schedule	Wide (2-orbit depth, 2 visits): v0.5 three months after each visit is obtained. v1.0 six months after the second visit. Deep (12-orbit depth, 13 visits, GOODS only): v0.5 three months after each visit is obtained. v1.0 six months after the last visit.
Acknowledgment	When using data from the CANDELS survey, please include the following acknowledgement: "This work is based on observations taken by the CANDELS Multi-Cycle Treasury Program with the NASA/ESA HST, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555." And cite the following papers: CANDELS Survey: Grogin et al., 2011, ApJS, in press, arxiv:1105.3753 CANDELS HST Data: Koekemoer et al., 2011, ApJS, in press, arxiv:1105.3754
Additional Information	Additional information is available on the CANDELS public web site: Science goals Survey description Observing schedule Field maps

Latest Data Releases

• The following table lists the most current epoch released in each field
• Click on the field name for a detailed epoch-by-epoch listing of all released data
• Click on the subregion name for tile maps
• Click on the version number to access the data on MAST

Field	Subregion1	Epoch1	Prog ID	Release Date	Documentation	Instrument/Filter	Download
GOODS-S	Deep JH	gsd10	12062	11/14/2011	README	WFC3/IR F105W ACS/WFC F606W ACS/WFC F814W ACS/WFC F850LP	v0.5
UDS	ALL	ALL	12064	11/14/2011	README	WFC3/IR F125W WFC3/IR F160W ACS/WFC F606W ACS/WFC F814W	v1.0
						WFC3/UVIS F350LP	v1.0
EGS	EGSa	egs02	12063	11/14/2011	README	ACS/WFC F606W ACS/WFC F814W WFC3/IR F125W WFC3/IR F160W	v0.5
						WFC3/UVIS F350LP	v0.5
COSMOS	--	--	TBD	Data Release in Spring 2012
GOODS-N	--	--	TBD	Data Release in Summer 2012

¹ The subregion and epoch number are defined in the observing schedule and tile maps.