Charge-Injection Device Imaging of Sirius with Contrast Ratios Greater than 1:26 Million

Abstract

The intrinsic nature of many astronomical objects, such as binary systems, exoplanets, circumstellar and debris disks, and quasar host galaxies, introduces challenging requirements for observational instrumentation and techniques. In each case, we encounter situations where the light from bright sources hampers our ability to detect surrounding fainter targets. To explore all features of such astronomical scenes, we must perform observations at the maximum possible contrast ratios. Charge-injection devices (CIDs) are capable of potentially exceeding contrast ratios of $\log_{10}{(CR)} > 9$ (i.e., 1 part in 1 billion) due to their unique readout architectures and inherent anti-blooming abilities. The on-sky testing of the latest generation of CIDs, the SpectraCAM XDR, has previously demonstrated direct contrast ratios in excess of 1 part in 20 million from sub-optimal ground-based astronomical observations that imposed practical limits on the maximum achievable contrast ratios. Here, we demonstrate the extreme contrast ratio imaging capabilities of the SXDR using observations of Sirius with the 1.0-m Jacobus Kapteyn Telescope, La Palma, Spain. Based on wavelet-based analysis and precise photometric and astrometric calibrations, we report a direct contrast ratio of $\Delta m_r = 18.54$, $\log_{10}{(CR)} = 7.41 \pm 0.08$, or $1$ part in $26$ million. This shows a $29\%$ increase in the achievable contrast ratios compared to the previous results.