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We present high resolution, deep imaging of interstellar comet 2I/Borisovtaken with the Hubble Space Telescope/Wide Field Camera 3 (HST/WFC3) on 2019December 8 UTC and 2020 January 27 UTC (HST GO 16040, PI Bolin) before andafter its perihelion passage in combination with HST/WFC3 images taken on 2019October 12 UTC and 2019 November 16 UTC (HST GO/DD 16009, PI Jewitt) before itsoutburst and fragmentation of March 2020, thus observing the comet in arelatively undisrupted state. We locate 1-2\arcsec~long (2,000 - 3,000 kmprojected length) jet-like structures near the optocenter of 2I that appear tochange position angles from epoch to epoch. With the assumption that the jet islocated near the rotational pole supported by its stationary appearance on$\sim$10-100 h time frames in HST images, we determine that 2I's pole pointsnear $\alpha$ = 322$\pm$10$^\circ$, $\delta$ = 37$\pm$10$^\circ$ ($\lambda$ =341$^\circ$, $\beta$ = 48$^\circ$) and may be in a simple rotation state.Additionally, we find evidence for possible periodicity in the HST time-serieslightcurve on the time scale of $\sim$5.3 h with a small amplitude of$\sim$0.05 mag implying a lower limit on its $b/a$ ratio of $\sim$1.5 unlikethe large $\sim$2 mag lightcurve observed for 1I/`Oumuamua. However, thesesmall lightcurve variations may not be the result of the rotation of 2I'snucleus due to its dust-dominated light-scattering cross-section. Therefore,uniquely constraining the pre-Solar System encounter, pre-outburst rotationstate of 2I may not be possible even with the resolution and sensitivityprovided by HST observations.

Constraints on the Spin-Pole Orientation, Jet Morphology and Rotation of Interstellar Comet 2I/Borisov with Deep HST Imaging