dsigma is an easy-to-use python package for measuring gravitational galaxy-galaxy lensing. Using a lensing catalog, it estimates excess surface density around a population of lenses, such as galaxies in the Sloan Digital Sky Survey or the Baryon Oscillation Spectroscopic Survey. It has a broadly applicable API and can utilize data from the Dark Energy Survey (DES), the Kilo-Degree Survey (KiDS), and the Hyper-Suprime Cam (HSC) lensing surveys, among others. With core computations written in C, dsigma is very fast. Additionally, dsigma provides out-of-the-box support for estimating covariances with jackknife resampling and calculating various summary statistics. Below is a plot showing the excess surface density around galaxies in the CMASS sample calculated with dsigma.

• Johannes Lange
• Song Huang

Documentation for dsigma with concept introductions, examples, and API documentation is available on readthedocs.

dsigma is listed in the Astronomy Source Code Library. If you find the code useful in your research, please cite Lange & Huang (2022).

dsigma is licensed under the MIT License.