Papers
Marlin et al. (calibration paper)
Arxiv Link - https://arxiv.org/pdf/2512.21903
ATLAS (Asteroid Terrestrial Last Alert System) is a time-domain survey using four telescopes, covering the entire sky. It has observed over 10,000 spectroscopically confirmed Type Ia supernovae (SNe~Ia), with thousands of cosmology-grade light curves (to be released as TITAN DR1). To prepare this massive, low-redshift dataset for cosmology, we evaluate and cross-calibrate ATLAS forced photometry using tertiary stars from the DES (Dark Energy Survey) Y6 release. The 5000 deg$^2$ DES footprint overlaps regions both in and out of the PS1 (Pan-STARRS DR1) footprint, allowing tests of the primary calibrator for the ATLAS Refcat2 catalog. Initial offsets are at the $\sim$40 mmag scale. To improve this we determine $\Delta$ zeropoint offsets for two cases: (1) pixel-to-pixel offsets within individual CCDs (reduced from $\sim$8 to $\sim$4 mmag RMS) and (2) chip-to-chip offsets across the 9 CCDs and filters (reduced from $\sim$17 to $\sim$3 mmag RMS). We also identify the largest systematic uncertainty as a transmission-function color dependence, requiring shifts in the assumed ATLAS filters at the $\sim$30 mmag level if uncorrected. We validate our calibration using (a) CALSPEC standards, (b) an independent tertiary catalog, and (c) distance moduli of cross-matched SNe~Ia, all showing improved consistency. Overall, we estimate combined calibration-related systematics at the $\sim$5--10 mmag level, supporting competitive cosmological constraints with the TITAN SN~Ia dataset.
Murakami et al. (Overview!)
We present a collection of 9999 SN Ia light curves from ATLAS. This is a comprehensive low-redshift SNe Ia, discovered by multiple surveys and observed by ATLAS telescopes. We apply series of diagnostics and cleanings to obtain a robust, cosmologically usable SNe Ia light curves — this includes chip-to-chip calibration of eight detectors, validation of centroid coordinates for forced photometry, correction of subtraction issues, etc. Of the 9999 SNe we collected, 4000 passes light curve quality cuts. This makes the ATLAS SNe Ia the largest low-redshift spectroscopically confirmed sample of SNe Ia accompanied by the spectroscopic redshifts of their host galaxies. We cross-calibrate the photometric system to DECam, which enables the combination with DES 5YR SNe.