DECaPS
Description
The Dark Energy Camera Plane Survey (DECaPS) is a multi-band imaging survey obtained with the Dark Energy Camera (DECam) to map the Galactic Plane. Browse these pages to learn more about DECaPS and to access the data. The DECaPS DR2 overview paper (Saydjari et al. 2022) and the DECaPS DR1 overview paper (Schlafly et al. 2017) describe the survey in detail, including its goals, survey strategy, reduction, and calibration. More information is also available on the DECaPS team website.
The decaps_dr2.object table and decaps_dr1.object table have been crossmatched against our default reference datasets within a 1.5 arcsec radius, nearest neighbor only. These tables will appear with x1p5 in their name in our table browser. Example: decaps_dr2.x1p5__object__gaia_dr3__gaia_source.
Data Releases
Second Data Release (DECaPS DR2)
DECaPS DR2 is a five-band optical and near-infrared survey of the southern Galactic plane with the Dark Energy Camera (DECam) on the 4.0m Blanco telescope at the Cerro Tololo Inter-American Observatory in Chile. The survey is designed to reach past the main-sequence turn-off at the distance of the Galactic center through a reddening E(B-V) of 1.5 mag and with average seeing around 1". The footprint covers |b| ≤ 10 deg and 6 deg > l > −124 deg, complementary to coverage by Pan-STARRS1. DECaPS DR2 simultaneously solves for the positions and fluxes of all the sources in each image, delivering positions and fluxes of 3.32 billion stars with up to 5 mmag repeatability. Most of these objects are highly reddened and deep in the Galactic disk, probing the structure and properties of the Milky Way and its interstellar medium.
| DECaPS DR2 Summary | |
|---|---|
| Area covered | 2700 deg² |
| Bands | grizY |
| Depth (5σ, grizY) | 23.5, 22.6, 22.1, 21.6, 20.8 mag |
| Number of objects | ∼3,300,000,000 |
The table below lists the tables available in the decaps_dr2 database. A few important notes about the object table are mentioned in the DECaPS Catalogs website and copied below for reference:
For quantities with an additional "_OK" field, the first is an average over all detections and the "_OK" field is limited to only "OK" detections. Detections are "OK" if no bad flag bits were set for the center pixel, the quality factor and RCHI2 pass a cut, and the flux uncertainty is nonzero. See the DECaPS DR2 release paper for these cuts and bad flag lists.
The obj_id for DECaPS DR2 has no relation to the obj_id for objects that also appear in DECaPS DR1.
All fluxes are reported in "maggies" (Mgy) which are equivalent to 3631 Jy and are a convenient unit so that -2.5*log10(flux) is in AB magnitudes.
| DECaPS DR2 Tables | |
|---|---|
| Table Name | Description |
| object | Band-Merged Catalog |
First Data Release (DECaPS DR1)
The DECaPS first data release took place in October 2017. It was published on the DECaPS team website, and described in an accompanying paper (Schlafly et al. 2017). The data release was also featured in a NOAO Currents article.
The DECaPS data were released in two stages at the Astro Data Lab. First, we released the object table, which corresponds to the band-merged catalogs loaded into a database table, as well as the survey tables (ccds, depth, imdb, zps). Second, we have released a measurement table consisting of the individual-image catalogs (meas). The measurement table was modified relative to the current version available on the DECaPS team website to include the obj_id allowing to join directly with the object table.
| DECaPS DR1 Summary | |
|---|---|
| Area covered | ∼1000 deg² |
| Bands | grizY |
| Depth (5σ, grizY) | 23.7, 22.8, 22.2, 21.8, 21.0 mag |
| Number of objects | ∼2,000,000,000 |
| Offsets to add to DECaPS mags to obtain AB (grizY) | 0.020, 0.033, 0.024, 0.028, 0.011 mag |
The table below lists the tables available in the decaps_dr1 database. A few important notes about the object table are listed on the DECaPS Catalogs webpage, and copied below for reference:
A "good" detection in these catalogs means that the detection's central pixel had no "bad" flags set in the Community Pipeline data quality image, and that at least 85% of the source's flux (according to the model PSF and model location of the source) lands in a pixel with non-zero weight, according to the Community Pipeline inverse variance image.
All fluxes are in units of "3631 Jy" so that the AB magnitudes of the stars are given by -2.5*log10(flux)
The absolute calibration is based on the Tonry et al. (2012) absolute calibration of PS1. Subsequent analyses (Scolnic et al., 2014, 2015) of the PS1 survey found offsets relative to AB. To shift the DECaPS magnitudes to the Scolnic et al. (2015) absolute calibration, offsets of 0.020, 0.033, 0.024, 0.028, and 0.011 mag must be added to the DECaPS grizY magnitudes, respectively.
| DECaPS DR1 Tables | |
|---|---|
| Table Name | Description |
| ccds | Brick CCD Table |
| depth | Brick Depth Table |
| imdb | Image Header Table |
| meas | Measurement Table |
| object | Band-Merged Catalog |
| zps | Zero Points, Flat Fields & QA Table |
Data Access
The DECaPS data are accessible by a variety of means:
Data Lab Table Access Protocol (TAP) service
TAP provides a convenient access layer to the DECaPS catalog database. TAP-aware clients (such as TOPCAT) can point to https://datalab.noirlab.edu/tap, select the decaps_dr2 database, and see the database tables and descriptions. You can also view the DECaPS tables and descriptions in the Data Lab table browser.
Data Lab Query Client
The Query Client is available as part of the Data Lab software distribution. The Query Client provides a Python API to Data Lab database services. These services include anonymous and authenticated access through synchronous or asynchronous queries of the catalog made directly to the database. Additional Data Lab services for registered users include personal database storage and storage through the Data Lab VOSpace.
The Query Client can be called from a Jupyter Notebook on the Data Lab Notebook server. Example notebooks are provided to users upon creation of their user account (register here), and are also available to browse on GitHub at https://github.com/astro-datalab/notebooks-latest.
Image Cutouts
Image cutouts can be retrieved by constructing URLs as follows:
JPEG: http://legacysurvey.org/viewer/jpeg-cutout/?layer=decaps2&ra=127.0026&dec=-41.6755&pixscale=4
FITS: http://legacysurvey.org/viewer/fits-cutout/?layer=decaps2&ra=127.0026&dec=-41.6755&pixscale=4
where "bands" is a string like "grz", "gz", "g", etc. Currently, the maximum size for cutouts (in number of pixels) is 512. Pixscale=0.262 will return (approximately) the native DECam pixels.
Jupyter Notebook Server
The Data Lab Jupyter Notebook server (authenticated service) contains examples of how to access and visualize the DECaPS catalog:
Acknowledgments
Long version: The Dark Energy Camera Plane Survey (DECaPS; NOAO Proposal ID 2016A-0323 and 2016B-0279, PI: D. Finkbeiner) includes data obtained at the Blanco telescope, Cerro Tololo Inter-American Observatory, National Optical Astronomy Observatory (NOAO).
The NSF NOIRLab is operated by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with the National Science Foundation. Database access and other data services are provided by the ASTRO Data Lab.
This project used data obtained with the Dark Energy Camera (DECam), which was constructed by the Dark Energy Survey (DES) collaboration. Funding for the DES Projects has been provided by the U.S. Department of Energy, the U.S. National Science Foundation, the Ministry of Science and Education of Spain, the Science and Technology Facilities Council of the United Kingdom, the Higher Education Funding Council for England, the National Center for Supercomputing Applications at the University of Illinois at Urbana-Champaign, the Kavli Institute of Cosmological Physics at the University of Chicago, Center for Cosmology and Astro-Particle Physics at the Ohio State University, the Mitchell Institute for Fundamental Physics and Astronomy at Texas A&M University, Financiadora de Estudos e Projetos, Fundação Carlos Chagas Filho de Amparo, Financiadora de Estudos e Projetos, Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro, Conselho Nacional de Desenvolvimento Científico e Tecnológico and the Ministério da Ciência, Tecnologia e Inovação, the Deutsche Forschungsgemeinschaft and the Collaborating Institutions in the Dark Energy Survey.
The Collaborating Institutions are Argonne National Laboratory, the University of California at Santa Cruz, the University of Cambridge, Centro de Investigaciones Enérgeticas, Medioambientales y Tecnológicas–Madrid, the University of Chicago, University College London, the DES-Brazil Consortium, the University of Edinburgh, the Eidgenössische Technische Hochschule (ETH) Zürich, Fermi National Accelerator Laboratory, the University of Illinois at Urbana-Champaign, the Institut de Ciències de l'Espai (IEEC/CSIC), the Institut de Física d'Altes Energies, Lawrence Berkeley National Laboratory, the Ludwig-Maximilians Universität München and the associated Excellence Cluster Universe, the University of Michigan, the National Optical Astronomy Observatory, the University of Nottingham, the Ohio State University, the OzDES Membership Consortium, the University of Pennsylvania, the University of Portsmouth, SLAC National Accelerator Laboratory, Stanford University, the University of Sussex, and Texas A&M University.
LaTeX version: This project used data obtained from the Dark Energy Camera (DECam), which was constructed by the Dark Energy (DES) collaboration. Funding for the DES Projects has been provided by the U.S. Department of Energy, the U.S. National Science Foundation, the Ministry of Science and Education of Spain, the Science and Technology Facilities Council of the United Kingdom, the Higher Education Funding Council for England, the National Center for Supercomputing Applications at the University of Illinois at Urbana-Champaign, the Kavli Institute of Cosmological Physics at the University of Chicago, the Center for Cosmology and Astro-Particle Physics at the Ohio State University, the Mitchell Institute for Fundamental Physics and Astronomy at Texas A&M University, Financiadora de Estudos e Projetos, Funda{\c c}{~a}o Carlos Chagas Filho de Amparo {`a} Pesquisa do Estado do Rio de Janeiro, Conselho Nacional de Desenvolvimento Cient{'i}fico e Tecnol{'o}gico and the Minist{'e}rio da Ci{^e}ncia, Tecnologia e Inova{\c c}{~a}o, the Deutsche Forschungsgemeinschaft, and the Collaborating Institutions in the Dark Energy Survey.
The Collaborating Institutions are Argonne National Laboratory, the University of California at Santa Cruz, the University of Cambridge, Centro de Investigaciones Energ{'e}ticas, Medioambientales y Tecnol{'o}gicas-Madrid, the University of Chicago, University College London, the DES-Brazil Consortium, the University of Edinburgh, the Eidgen{"o}ssische Technische Hochschule (ETH) Z{"u}rich, Fermi National Accelerator Laboratory, the University of Illinois at Urbana-Champaign, the Institut de Ci{`e}ncies de l'Espai (IEEC/CSIC), the Institut de F{'i}sica d'Altes Energies, Lawrence Berkeley National Laboratory, the Ludwig-Maximilians Universit{"a}t M{"u}nchen and the associated Excellence Cluster Universe, the University of Michigan, the National Optical Astronomy Observatory, the University of Nottingham, the Ohio State University, the OzDES Membership Consortium, the University of Pennsylvania, the University of Portsmouth, SLAC National Accelerator Laboratory, Stanford University, the University of Sussex, and Texas A&M University.
Short version (for Letters journals ONLY): This project used data obtained with the Dark Energy Camera (DECam), which was constructed by the Dark Energy Survey (DES) collaboration. Funding for the DES Projects has been provided by the DOE and NSF (USA), MISE (Spain), STFC (UK), HEFCE (UK), NCSA (UIUC), KICP (U. Chicago), CCAPP (Ohio State), MIFPA (Texas A&M), CNPQ, FAPERJ, FINEP (Brazil), MINECO (Spain), DFG (Germany) and the collaborating institutions in the Dark Energy Survey, which are Argonne Lab, UC Santa Cruz, University of Cambridge, CIEMAT-Madrid, University of Chicago, University College London, DES-Brazil Consortium, University of Edinburgh, ETH Zürich, Fermilab, University of Illinois, ICE (IEEC-CSIC), IFAE Barcelona, Lawrence Berkeley Lab, LMU München and the associated Excellence Cluster Universe, University of Michigan, NOAO, University of Nottingham, Ohio State University, OzDES Membership Consortium, University of Pennsylvania, University of Portsmouth, SLAC National Lab, Stanford University, University of Sussex, and Texas A&M University.
LaTeX version: This project used data obtained with the Dark Energy Camera (DECam), which was constructed by the Dark Energy Survey (DES) collaboration. Funding for the DES Projects has been provided by the DOE and NSF (USA), MISE (Spain), STFC (UK), HEFCE (UK), NCSA (UIUC), KICP (U. Chicago), CCAPP (Ohio State), MIFPA (Texas A&M), CNPQ, FAPERJ, FINEP (Brazil), MINECO (Spain), DFG (Germany) and the collaborating institutions in the Dark Energy Survey, which are Argonne Lab, UC Santa Cruz, University of Cambridge, CIEMAT-Madrid, University of Chicago, University College London, DES-Brazil Consortium, University of Edinburgh, ETH Z{"u}rich, Fermilab, University of Illinois, ICE (IEEC-CSIC), IFAE Barcelona, Lawrence Berkeley Lab, LMU M{"u}nchen and the associated Excellence Cluster Universe, University of Michigan, NOAO, University of Nottingham, Ohio State University, OzDES Membership Consortium, University of Pennsylvania, University of Portsmouth, SLAC National Lab, Stanford University, University of Sussex, and Texas A&M University.
