Possible Activity in 468861 (2013 LU28)

Manx comets are objects on long period (LP) comet orbits that lack the typical outgassing from near surface ices of LP comets as they approach perihelion. These comets are of particular interest because they may help constrain solar system formation models. The Manx candidate 2013 LU28 was discovered as an inactive asteroidal object on 2013 June 8 at a heliocentric distance of 21.8 au. At such a large distance from perihelion, this allows for the unique chance to observe this object over a long period of time on its approach to the sun, and to monitor any possible activity. We present an analysis of the activity and physical properties of Manx candidate 2013 LU28. Images and photometric data were obtained of 2013 LU28 from multiple telescopes from pre-discovery data in 2010 until the present. These data were used to determine the color of our target and its spectral reflectivity, as well as to determine if any activity was present. Its spectral reflectivity is consistent with typical organic rich comet surfaces with colors of g'-r' = 0.97 ± 0.02, r'-i' = 0.43 ± 0.02 and r'-z' = 0.65 ± 0.03, corresponding to a spectral reflectivity slope of 30±3 %/100 nm. There is no obvious indication of dust coma in deep stacked images, however, comparison with the heliocentric light curve suggests possible activity from r ~ 20 to 13 au. This is consistent with subsurface CO or CO2 outgassing. Surface brightness profiles show that there is an upper limit of approximately 1 kg/s of micron sized dust that can be produced without us detecting it between 14 and 17 au. The heliocentric light curve when it is not active is used to estimate the size of the bare nucleus, which was ~55.7±0.3 km. We will also report on upper limits on the nucleus size from the NEOWISE survey.