A Precision Photometric Comparison between SDSS-II and CSP Type Ia Supernova Data

TL;DR

This study compares photometric data from SDSS-II and CSP for Type Ia supernovae, demonstrating high consistency with minimal systematic uncertainties, thereby validating the combined use of these datasets for supernova research.

Contribution

The paper provides a detailed comparison and transformation of CSP data into the SDSS system, quantifying systematic uncertainties and demonstrating the high agreement between the two surveys.

Findings

Average magnitude differences are ≤ 0.011 magnitudes in ugri.

Systematic uncertainties are at or below 0.023 magnitudes.

Good agreement in the u band despite limited data.

Abstract

Consistency between Carnegie Supernova Project (CSP) and SDSS-II supernova (SN) survey ugri measurements has been evaluated by comparing SDSS and CSP photometry for nine spectroscopically confirmed Type Ia supernova observed contemporaneously by both programs. The CSP data were transformed into the SDSS photometric system. Sources of systematic uncertainty have been identified, quantified, and shown to be at or below the 0.023 magnitude level in all bands. When all photometry for a given band is combined, we find average magnitude differences of equal to or less than 0.011 magnitudes in ugri, with rms scatter ranging from 0.043 to 0.077 magnitudes. The u band agreement is promising, with the caveat that only four of the nine supernovae are well-observed in u and these four exhibit an 0.038 magnitude supernova-to-supernova scatter in this filter.