Astronomical image simulation

Hubble Ultra Deep Field

Hubble Ultra Deep Field

Essential to the development of optimal weak lensing survey strategies is the state-of-the-art weak lensing image simulation pipeline that I helped upgrade and test while working at Caltech and the NASA Jet Propulsion Laboratory. Written in IDL, this simulation package creates images that are empirically based on the Ultra Deep Field dataset from the Hubble Space Telescope. The images of real galaxies are modeled using a set of basis functions called “shapelets” — a complete, orthonormal set of 2D basis functions — the statistical distributions of which can then be re-sampled to produce a new random galaxy distribution.

Color images can then be randomly created and populated with these simulated galaxies with the desired parameters for any hypothetical ground- or space-based survey, including field size, exposure time, telescope mirror size, pixel resolution, field star density, and a variety of detector noise sources. Also crucial for weak lensing tests is the ability to change the point spread function (the way that point sources such as stars become smeared out by various effects) and overall shearing of the images.


This pipeline has been used in a large number of studies. It is useful for 1. the development and testing of weak lensing shear extraction algorithms and 2. the study and quantification of various lensing systematics (including data compression). In particular it has been used in the Shear TEsting Program (STEP) data analysis challenges (Heymans et al. 2006; Massey et al. 2007), and is freely available for download for any scientific or educational purposes.

Dobke et al. (2010). Published in Publications of the Astronomical Society of the Pacific.