Testing Progenitor Models Using the Late-Time Light Curve of Supernova 1992A

The dominant radioactive energy source powering Type Ia supernova light curves is expected to switch from the decay of $^{56}$Co to $^{57}$Co at very late epochs. We use archival HST images of SN1992A obtained more than 900 days after explosion to constrain its cobalt isotopic abundance ratio and compare it to the well-studied event SN2011fe. We confirm the $^{57}$Co / $^{56}$Co ratio for SN2011fe of $0.026\pm 0.004$ found by arXiv:1608.01155, consistent with a "double degenerate" progenitor scenario. For SN1992A, we find a ratio of $0.034\pm 0.010$, but the large uncertainty does not allow us to differentiate between progenitor models