Extended Data Fig. 1: Photometry of the multiply imaged SN: image differencing and the blackbody fitting.
From: Shock cooling of a red-supergiant supernova at redshift 3 in lensed images
We used GALFIT51 to fit bright sources in the lensing system and subtracted the best-fit model from the field prior to measuring the flux. a–c, The template image (a), the best-fit GALFIT model (b), and the residual through the HST ACS-WFC F814W filter (c). d, The WFC3-IR F160W difference image by subtracting the template from the event image directly. e, The difference image using our GALFIT-based method, where we subtracted the PSF-convolved best-fit GALFIT source models from the images, and then calculated the difference from GALFIT residuals between the coadded images and the event images. We can see that this method can reduce the significant residual from the mismatched PSFs around bright sources as shown in d. f–h, Distributions of effective temperature and luminosity from the MCMC samples from fitting the blackbody emission into the photometry of each SN image.
