Simulations with Chromatic Effects for Shear Calibration

[sidneymau]

Simulations with Chromatic Effects for Shear Calibration

Making simulations to test how shear calibration/measurement algorithms (e.g., metadetect) respond to the presence of chromatic effects, including chromatic PSFs and galaxies with realistic SEDs. This issue is mostly to keep myself accountable

Contacts: Sidney Mau (@sidneymau ) Day/Time: Mon–Fri Main communication channel: N/A GitHub repo: https://github.com/LSSTDESC/shear-bias-sims (this will probably be renamed ~soon) Zoom room (if applicable): N/A

Goals and deliverable

This is probably more than I can expect to finish during sprint week...

• [ ] verify that current sims are working with low SNR test
• [x] implement hexagonal grid placement of galaxies for denser packing
• [ ] implement randomly scattered scenes using mixed_scene
• [x] draw the noise realization from GalSim rather than reconstructing directly
• [ ] add configurable seed and random sampling to galaxy, psf, etc. parameters
• [ ] start thinking about chromaticity

Resources and skills needed

• GalSim
• metadetect
• slurm

Detailed description

I'm still in the early stages of this project, so I mostly just need to spend time getting all of the pieces together and working

[sidneymau]

Hexagonal grid working (though I can do better with how the parameters are defined/read from the config). The code is mostly general enough to accept any set of tiling vectors, and I'll try to implement the image type in this way. If this seems sufficiently useful, I'll work on cleaning up the relevant code and submitting a PR into GalSim.

[sidneymau]

Now using GalSim functions to draw weight and noise using the same functionality as the config parser; see https://github.com/LSSTDESC/shear-bias-sims/blob/main/shear_bias_sims/run_utils.py#L71-L88.