Buzzard DR1


The Buzzard DR1 catalog is a new suite of cosmological simulations that is tailored for the testing and validation of combined galaxy clustering and weak-lensing analyses. Buzzard DR1 accurately reproduces many important aspects of the Dark Energy Survey Year 3 (DES Y3) data, including photometric redshift and magnitude distributions, and the relevant set of two-point clustering and weak-lensing statistics.

The Buzzard DR1 table contains a simulated galaxy catalog with positions, velocities, Spectral Energy Distributions (SEDs), broad-band photometry in a number of relevant passbands, weak-lensing shear and convergence, half-light radii, and ellipticities. The galaxy catalog was generated using the ADDGALS algorithm, with ray-traced weak-lensing statistics computed via CALCLENS (see their GitHub page). The underlying cosmological lightcone simulations were run using GADGET-2.

The simulation spans one quarter of the sky extending to z=2.3, and is complete out to that redshift to r=27 as described in DeRose et al. 2019 and DeRose et al. 2022. Given its large area and realism, it is ideal for simulated studies of large scale structure observables, and has been used in a number of analyses in DES, DESI, and the Rubin Observatory, among others. In order to facilitate simulated analyses of existing and upcoming large scale structure surveys, we provide photometry in DECam (ugrizY), VISTA (zYJHKs), WISE (W1, W2), Rubin (ugrizY), and Roman (YJHK) passbands.

Galaxies contain lensed and un-lensed magnitudes, positions, and ellipticities. SEDs are represented with KCORRECT coefficients.

We are publicly releasing one of a set of nine catalogs. The unreleased catalogs are the same in every respect, but are built on lightcones simulated with different initial seeds. Access to these additional catalogs is available upon request to the catalog creators (Joe DeRose: In the future, we also expect to release DES and DESI specific catalogs, with galaxy samples selected specific to those surveys, such as redMaGiC and redMaPPer for DES and the four main survey galaxy target classes for DESI.

Column descriptions for the buzzard_dr1.main table at Astro Data Lab are available through our table browser. We add the following columns for convenience: htm9, nest4096, ring256, random_id, elon, elat, glon, glat.

Buzzard DR1 data
Number of objects 3,075,827,818
Number of columns 107
Area covered 10,316 deg2
Bands DECam: u, g, r, i, z, Y
Roman: Y, J, H, K
Rubin: u, g, r, i, z, Y
VISTA: Z, Y, J, H, Ks
WISE: W1, W2

Data Access

The Buzzard DR1 data are accessible through several means:

Data Lab Table Access Protocol (TAP) service

TAP provides a convenient access layer for the Buzzard DR1 catalog database table. TAP-aware clients (such as TOPCAT) can point to, select the buzzard_dr1 database, and see the database table and descriptions. Descriptions of the associated table can also be found on the Data Lab table browser.

Data Lab Query Manager

The Query Manager is available as part of the Data Lab software distribution. The Query Manager client provides a Python API to Data Lab database services. These services include anonymous access through synchronous queries of the catalog made directly to the database as well as authenticated access, asynchronous queries, personal database storage, and storage through the Data Lab VOSpace.