I’ve contributed two new notebooks related to Difference Image Analysis (DIA) with the DP0.2 data set. These notebooks might be of interest to anyone working with difference-image photometry or Type Ia supernovae and their host galaxies.
Both new notebooks are available in the “dia_exploration/” directory of our shared “delegate-contributions-dp02” repository.
dia_template_contamination.ipynb
For DP0.2, the template images were constructed using the 30% of the images with the best seeing over the 6-year DC2 simulation. This results in some flux in the template images (“template contamination”) for some supernovae, which is then subtracted during difference image analysis, leading to negative or reduced difference-image fluxes. This notebook estimates that 50% of SNIa lightcurves are affected by template contamination, and demonstrates a way to correct for template contamination using the forced photometry fluxes during “off-peak” visits obtained before and after the supernova.
dia_SNIa_host_association.ipynb
The DP0.2 DiaObjects catalog does not contain the host association parameters described in the Rubin Observatory Data Products Definitions Document (DPDD; ls.st/dpdd) and in the Data Management Tech Note on “Host Galaxy Association for DIAObjects” (DMTN-151), but future data releases will. This notebook provides an introduction to those future parameters, and demonstrates the fraction of SNIa that are associated with their true host as a function of redshift for a few simple methods of host association.
Check them out if you’re interested, and reach out (reply in this thread or send me a direct message) if you have any comments or questions.
And as always, please feel free to make your own contributions to any of the directories in the “delegate-contributions-dp02” repository, or start a new directory there for yourself.