Faint moving object detection, and the Low Signal-to-Noise recovery of Main Belt comet P/2008 R1 Garradd

TL;DR

This paper details the techniques used to recover a faint Main Belt comet at very low signal-to-noise ratios, revealing insights into its size, composition, and implications for ice survival in small solar system bodies.

Contribution

It introduces advanced noise reduction and detection methods enabling the recovery of extremely faint objects in crowded fields, with implications for understanding comet composition.

Findings

Detected P/2008 R1 Garradd at magnitude Rc=26.1±0.2

Estimated the comet's radius at approximately 0.3 km

Discussed the implications for ice survival in small bodies

Abstract

We describe the recovery of faint Main Belt comet P/2008 R1 Garradd using several telescopes, culminating in a successful low $S/N$ recovery with the Gemini North telescope with GMOS. This recovery was a time-critical effort for a mission proposal, and had to be performed in a crowded field. We describe techniques and software tools for eliminating systematic noise artifacts and stellar residuals, bringing the final detection image statistics close to the Gaussian ideal for a median image stack, and achieving a detection sensitivity close to this theoretical optimum. The magnitude of $R_c$=26.1$\pm$0.2 with an assumed geometric albedo of 0.05 corresponds to a radius of 0.3 km. For ice to have survived in this object over the age of the solar system, it implies that the object is a more recent collisional fragment. We discuss the implications of the unexpectedly faint magnitude and nuclear size of P/2008 R1 on the survival of ice inside very small bodies.