The first two observational sky "blocks" of the Outer Solar System Origins Survey (OSSOS) have significantly increased the number of well characterized observed trans-Neptunian objects (TNOs) in Neptuneʼs mean motion resonances. We describe the 31 securely resonant TNOs detected by OSSOS so far, and we use them to independently verify the resonant population models from the Canada-France Ecliptic Plane Survey (CFEPS), with which we find broad agreement. We confirm that the 5:2 resonance is more populated than models of the outer solar systemʼs dynamical history predict; our minimum population estimate shows that the high-eccentricity (e > 0.35) portion of the resonance is at least as populous as the 2:1 and possibly as populated as the 3:2 resonance. One OSSOS block was well suited for detecting objects trapped at low libration amplitudes in Neptuneʼs 3:2 resonance, a population of interest in testing the origins of resonant TNOs. We detected three 3:2 objects with libration amplitudes below the cutoff modeled by CFEPS; OSSOS thus offers new constraints on this distribution. The OSSOS detections confirm that the 2:1 resonance has a dynamically colder inclination distribution than either the 3:2 or 5:2 resonances. Using the combined OSSOS and CFEPS 2:1 detections, we constrain the fraction of 2:1 objects in the symmetric mode of libration to 0.2-0.85; we also constrain the fraction of asymmetric librators in the leading island, which has been theoretically predicted to vary depending on Neptuneʼs migration history, to be 0.05-0.8. Future OSSOS blocks will improve these constraints.

We report the discovery, tracking and detection circumstances for 85 trans-Neptunian objects (tnos) from the first 42 deg 2 of the Outer Solar System Origins Survey (ossos). This ongoing r-band Solar System survey uses the 0.9 deg 2 field-ofview MegaPrime camera on the 3.6 m Canada-France-Hawaii Telescope. Our orbital elements for these tnos are precise to a fractional semi-major axis uncertainty < 0.1%. We achieve this precision in just two oppositions, as compared to the normal 3-5 oppositions, via a dense observing cadence and innovative astrometric technique. These discoveries are free of ephemeris bias, a first for large trans-Neptunian surveys. We also provide the necessary information to enable models of tno orbital distributions to be tested against our tno sample. We confirm the existence of a cold "kernel" of objects within the main cold classical Kuiper belt, and infer the existence of an extension of the "stirred" cold classical Kuiper belt to at least several au beyond the 2:1 mean motion resonance with Neptune. We find that the population model of Petit et al. (2011) remains a plausible representation of the Kuiper belt. The full survey, to be completed in 2017, will provide an exquisitely characterized sample of important resonant tno populations, ideal for testing models of giant planet migration during the early history of the Solar System.

The accumulating, but small, set of large semi-major axis trans-Neptunian objects (TNOs) shows an apparent clustering in the orientations of their orbits. This clustering must either be representative of the intrinsic distribution of these TNOs, or else arise as a result of observation biases and/or statistically expected variations for such a small set of detected objects. The clustered TNOs were detected across different and independent surveys, which has led to claims that the detections are therefore free of observational bias. This apparent clustering has led to the so-called "Planet 9" hypothesis that a super-Earth currently resides in the distant solar system and causes this clustering. The Outer Solar System Origins Survey (OSSOS) is a large program that ran on the Canada-France-Hawaii Telescope from 2013-2017, discovering more than 800 new TNOs. One of the primary design goals of OSSOS was the careful determination of observational biases that would manifest within the detected sample. We demonstrate the striking and non-intuitive biases that exist for the detection of TNOs with large semi-major axes. The eight large semi-major axis OSSOS detections are an independent dataset, of comparable size to the conglomerate samples used in previous studies. We conclude that the orbital distribution of the OSSOS sample is consistent with being detected from a uniform underlying angular distribution.

Several different classes of trans-Neptunian objects (TNOs) have been identified based on their optical and near-infrared colors. As part of the Colours of the Outer Solar System Origins Survey (Col-OSSOS), we have obtained g-, r-, and z-band photometry of 26 TNOs using Subaru and Gemini Observatories. Previous color surveys have not utilized z-band reflectance, and the inclusion of this band reveals significant surface reflectance variations between sub-populations. The colors of TNOs in g−r and r−z show obvious structure, and appear consistent with the previously measured bi-modality in g−r. The distribution of colors of the two dynamically excited surface types can be modeled using the two-component mixing models from Fraser & Brown. With the combination of g−r and r−z, the dynamically excited classes can be separated cleanly into red and neutral surface classes. In g−r and r−z, the two dynamically excited surface groups are also clearly distinct from the cold classical TNO surfaces, which are red, with  -g r 0.85 and r−z  0.6, while all dynamically excited objects with similar g−r colors exhibit redder r−z colors. The z-band photometry makes it possible for the first time to differentiate the red excited TNO surfaces from the red cold classical TNO surfaces. The discovery of different r−z colors for these cold classical TNOs makes it possible to search for cold classical surfaces in other regions of the Kuiper Belt and to completely separate cold classical TNOs from the dynamically excited population, which overlaps in orbital parameter space.