Program: GS-2017B-DD-7

On October 19, 2017 an inactive object on a long-period comet orbit was discovered by the Pan-STARRS1 survey. Initially, it was of great interest because it was found inactive at a heliocentric distance of 1.2 au, having come within 0.25 au of the Sun on its 2017 Sep. 9 perihelion. The orbit and lack of activity suggested that it could be one of the ``Manx comets'', possible inner solar system material that was ejected into the Oort cloud during solar system formation. However, additional astrometry showed that this might be an entirely new type of object, on a genuine hyperbolic orbit. This would represent the first detection of an extrasolar planetesimal in our solar system. We propose to characterize the surface via grizY-photometry to determine the mineralogical taxonomy to compare it to bodies from our own solar system, perform a sensitive search for and activity-driven dust coma, to pin down its orbit, and to constrain its rotational light curve to learn more of its shape and dynamical origin.