Posts by Collection



CFHTLenS and RCSLenS: testing photometric redshift distributions using angular cross-correlations with spectroscopic galaxy surveys

Published in Monthly Notices of the Royal Astronomical Society, 2016

Constraining photometric redshift distributions using spectroscopic and photometric angular cross-clustering.

Recommended citation: Choi, A., Heymans, C., Blake, C., et al. (2016). "CFHTLenS and RCSLenS: Testing Photometric Redshift Distributions Using Angular Cross-Correlations with Spectroscopic Galaxy Surveys" MNRAS, 463, 3737



The Brighter Fatter Effect in H4RG-10 Detectors


The Wide Field Infrared Survey Telescope (WFIRST) is an upcoming NASA observatory that will investigate the origins of cosmic acceleration using weak gravitational lensing. WFIRST will perform galaxy shape measurements using Teledyne H4RG-10 detectors; thus it is essential to understand inter-pixel non-linearities like the brighter-fatter effect (BFE) and non-linear inter-pixel capacitance (NL-IPC) that could cause systematic errors in the lensing analysis. The non-destructive readout capability of the H4RG-10 detectors enables correlation measurements on flat field data not only between pixels but also between time frames. In this talk, I will present a correlation analysis of flat field data (obtained from the Detector Characterization Laboratory) for one of the WFIRST prototype detectors. After correcting for classical non-linearity, we find a statistically significant residual correlation signal. We leverage the time dimension of this data set to perform some tests that suggest that the BFE is the dominant mechanism. The flat field statistics continue to provide a wealth of information that will eventually help us calibrate WFIRST data and obtain accurate cosmological parameters.


Teaching Assistant

Undergraduate Introductory Physics 7A/B, University of California at Davis, Physics Department, 2004

Over three quarters from Fall, 2004 through Spring, 2005, I led 5 Discussion/Lab sections (each ~25 students) for Physics 7A/B, which is an introductory undergraduate course for pre-meds and students majoring in other STEM fields aside from physics.

Teaching Assistant and Lecturer, Astro 10L

Observing Lab, University of California at Davis, Physics, 2005

I led the lab component of Astro 10, which was an introductory course in astronomy for undergraduates. At the beginning of each meeting, I delivered a quick lecture (~30 minutes), for which I created the slides. We then went on to observe and complete exercises using small telescopes on the rooftop of the Physics Building.

Weak Gravitational Lensing Course

Graduate course, University of Edinburgh, 2015

This was a 10 week course that I organized. I also presented 4 of the 10 lectures and arranged for guest lecturers from the Royal Observatory of Edinburgh to lead the rest.