Haumea is one of the most interesting and intriguing trans-Neptunian objects (TNOs). It is a large, bright, fast rotator, and its spectrum indicates nearly pure water ice on the surface. It has at least two satellites and a dynamically related family of more than 10 TNOs with very similar proper orbital parameters and similar surface properties. The Haumean family is the only one currently known in the trans-Neptunian belt. Various models have been proposed, but the formation of the family remains poorly understood. In this work, we have investigated the rotational properties of the family members and unconfirmed family candidates with short-term variability studies, and report the most complete review to date. We present results based on five years of observations and report the short-term variability of five family members and seven candidates. The mean rotational periods, from Maxwellian fits to the frequency distributions, are 6.27 +/- 1.19 hr for the confirmed family members, 6.44 +/- 1.16 hr for the candidates, and 7.65 +/- 0.54 hr for other TNOs (without relation to the family). According to our study, there is a possibility that Haumea family members rotate faster than other TNOs; however, the sample of family members is still too limited for a secure conclusion. We also highlight the fast rotation of 2002 GH(32). This object has a 0.36 +/- 0.02 mag amplitude lightcurve and a rotational period of about 3.98 hr. Assuming 2002 GH(32) is a triaxial object in hydrostatic equilibrium, we derive a lower limit to the density of 2.56 g cm(-3). This density is similar to Haumea's and much more dense than other small TNO densities.

We present observations using the Baade Magellan and Canada-France-Hawaii telescopes showing that main-belt comet 324P/La Sagra, formerly known as P/2010 R2, has become active again for the first time since originally observed to be active in 2010-2011. The object appears point-source-like in 2015 March and April as it approached perihelion (true anomaly of nu similar to 300 degrees), but was similar to 1 mag brighter than expected if inactive, suggesting the presence of unresolved dust emission. Activity was confirmed by observations of a cometary dust tail in 2015 May and June. We find an apparent net dust production rate of (M) over dot(d) less than or similar to 0.1 kg s(-1) during these observations. 324P is now the fourth main-belt comet confirmed to be recurrently active, a strong indication that its activity is driven by sublimation. It now has the largest confirmed active range of all likely main-belt comets, and also the most distant confirmed inbound activation point at R similar to 2.8 au. Further observations during the current active period will allow direct comparisons of activity strength with 324P's 2010 activity.

We are conducting a survey for distant solar system objects beyond the Kuiper Belt edge (similar to 50 au) with new wide-field cameras on the Subaru and CTIO telescopes. We are interested in the orbits of objects that are decoupled from the giant planet region to understand the structure of the outer solar system, including whether a massive planet exists beyond a few hundred astronomical units as first reported in 2014 by Trujillo & Sheppard. In addition to discovering extreme trans-Neptunian objects detailed elsewhere, we found several objects with high perihelia (q > 40 au) that differ from the extreme and inner Oort cloud objects due to their moderate semimajor axes (50 < a < 100 au) and eccentricities (e less than or similar to 0.3). Newly discovered objects 2014 FZ71 and 2015 FJ345 have the third and fourth highest perihelia known after Sedna and 2012 VP113, yet their orbits are not nearly as eccentric or distant. We found several of these high-perihelion but moderate orbit objects and observe that they are mostly near Neptune mean motion resonances (MMRs) and have significant inclinations (i > 20 degrees). These moderate objects likely obtained their unusual orbits through combined interactions with Neptune's MMRs and the Kozai resonance, similar to the origin scenarios for 2004 XR190. We also find the distant 2008 ST291 has likely been modified by the MMR+KR mechanism through the 6: 1 Neptune resonance. We discuss these moderately eccentric distant objects along with some other interesting low inclination outer classical belt objects like 2012 FH84 discovered in our ongoing survey.

We use the AllWISE Data Release to continue our search for Wide-field Infrared Survey Explorer (WISE)-detected motions. In this paper, we publish another 27,846 motion objects, bringing the total number to 48,000 when objects found during our original AllWISE motion survey are included. We use this list, along with the lists of confirmed WISE-based motion objects from the recent papers by Luhman and by Schneider et al., and candidate motion objects from the recent paper by Gagne et al., to search for widely separated, common-proper-motion systems. We identify 1039 such candidate systems. All 48,000 objects are further analyzed using color-color and color-mag plots to provide possible characterizations prior to spectroscopic follow-up. We present spectra of 172 of these, supplemented with new spectra of 23 comparison objects from the literature, and provide classifications and physical interpretations of interesting sources. Highlights include: (1) the identification of three G/K dwarfs that can be used as standard candles to study clumpiness and grain size in nearby molecular clouds because these objects are currently moving behind the clouds, (2) the confirmation/discovery of several M, L, and T dwarfs and one white dwarf whose spectrophotometric distance estimates place them 5-20 pc from the Sun, (3) the suggestion that the Na I "D" line be used as a diagnostic tool for interpreting and classifying metal-poor late-M and L dwarfs, (4) the recognition of a triple system including a carbon dwarf and late-M subdwarf, for which model fits of the late-M subdwarf (giving [Fe/H] approximate to -1.0) provide a measured metallicity for the carbon star, and (5) a possible 24 pc distant K5 dwarf + peculiar red L5 system with an apparent physical separation of 0.1 pc.

Recently, Sheppard et al. presented the discovery of seven new trans-Neptunian objects with moderate eccentricities, perihelia beyond 40 au, and semimajor axes beyond 50 au. Like the few previously known objects on similar orbits, these objects' semimajor axes are just beyond the Kuiper Belt edge and clustered around Neptunian mean motion resonances (MMRs). These objects likely obtained their observed orbits while trapped within MMRs, when the Kozai-Lidov mechanism raised their perihelia and weakened Neptune's dynamical influence. Using numerical simulations that model the production of this population, we find that high-perihelion objects near Neptunian MMRs can constrain the nature and timescale of Neptune's past orbital migration. In particular, the population near the 3:1 MMR (near 62 au) is especially useful due to its large population and short dynamical evolution timescale. If Neptune finishes migrating within similar to 100 Myr or less, we predict that over 90% of high-perihelion objects near the 3:1 MMR will have semimajor axes within 1 au of each other, very near the modern resonance's center. On the other hand, if Neptune's migration takes similar to 300 Myr, we expect similar to 50% of this population to reside in dynamically fossilized orbits over similar to 1 au closer to the Sun than the modern resonance. We highlight 2015 KH162 as a likely member of this fossilized 3:1 population. Under any plausible migration scenario, nearly all high-perihelion objects in resonances beyond the 4:1 MMR (near 76 au) reach their orbits well after Neptune stops migrating and compose a recently generated, dynamically active population.

We are performing a wide and deep survey for extreme distant solar system objects. Our goal is to understand the high-perihelion objects Sedna and 2012 VP113 and determine if an unknown massive planet exists in the outer solar system. The discovery of new extreme objects from our survey of some 1080 square degrees of sky to over 24th magnitude in the r-band are reported. Two of the new objects, 2014 SR349 and 2013 FT28, are extreme detached trans-Neptunian objects, which have semimajor axes greater than 150 au and perihelia well beyond Neptune (q > 40 au). Both new objects have orbits with arguments of perihelia within the range of the clustering of this angle seen in the other known extreme objects. One of these objects, 2014 SR349, has a longitude of perihelion similar to the other extreme objects, but 2013 FT28 is about 180 degrees away or anti-aligned in its longitude of perihelion. We also discovered the first outer Oort Cloud object with a perihelion beyond Neptune, 2014 FE72. We discuss these and other interesting objects discovered in our ongoing survey. All the high semimajor axis (a > 150 au) and high-perihelion (q > 35 au) bodies follow the previously identified argument of perihelion clustering as first reported and explained as being from an unknown massive planet in 2014 by Trujillo & Sheppard, which some have called Planet X or Planet Nine. With the discovery of 2013 FT28 on the opposite side of the sky, we now report that the argument of perihelion is significantly correlated with the longitude of perihelion and orbit pole angles for extreme objects and find there are two distinct extreme clusterings anti-aligned with each other. This previously unnoticed correlation is further evidence of an unknown massive planet on a distant eccentric inclined orbit, as extreme eccentric objects with perihelia on opposite sides of the sky (180 degrees longitude of perihelion differences) would approach the inclined planet at opposite points in their orbits, thus making the extreme objects prefer to stay away from opposite ecliptic latitudes to avoid the planet (i.e., opposite argument of perihelia or orbit pole angles).

We report photometric observations of the trans-Neptunian object 2004 TT357 obtained in 2015 and 2017 using the 4.3 m Lowell's Discovery Channel Telescope. We derive a rotational period of 7.79 +/- 0.01. hr and a peak-to-peak lightcurve amplitude of 0.76 +/- 0.03. mag. 2004 TT357 displays a large variability that can be explained by a very elongated single object or can be due to a contact/close binary. The most likely scenario is that 2004 TT357 is a contact binary. If it is in hydrostatic equilibrium, we find that the lightcurve can be explained by a system with a mass ratio q(min) = 0.45 +/- 0.05, and a density rho(min) = 2 g cm(-3), or less likely a system with q(max) = 0.8 +/- 0.05, and rho(max) = 5 g cm(-3). Considering a single triaxial ellipsoid in hydrostatic equilibrium, we derive a lower limit to the density of 0.78 g cm(-3), and an elongation (a/b) of 2.01 assuming an equatorial view. From Hubble Space Telescope data, we report no resolved companion orbiting 2004 TT357. Despite an expected high fraction of contact binaries in the trans-Neptunian belt, 2001. QG(298) is the unique confirmed contact binary in the transNeptunian belt, and 2004 TT357 is only the second candidate to this class of systems, with 2003 SQ(317).

Images of the Kuiper Belt object (126719) 2002 CC249 obtained in 2016 and 2017 using the 6.5 m Magellan-Baade Telescope and the 4.3 m Discovery Channel Telescope are presented. A light curve with a periodicity of 11.87 +/- 0.01 hr and a peak-to-peak amplitude of 0.79 +/- 0.04 mag is reported. This high amplitude double-peaked light curve can be due to a single elongated body, but it is best explained by a contact binary system from its U-/V-shaped light curve. We present a simple full-width-at-half-maximum test that can be used to determine if an object is likely a contact binary or an elongated object based on its light curve. Considering that 2002 CC249 is in hydrostatic equilibrium, a system with a mass ratio q(min) = 0.6, and a density rho(min) = 1 g cm(-3), or less plausible a system with q(max) = 1, and rho(max) = 5 g cm(-3) can interpret the light curve. Assuming a single Jacobi ellipsoid in hydrostatic equilibrium and an equatorial view, we estimate rho >= 0.34 g cm(-3), and a/b = 2.07. Finally, we report a new color study showing that 2002 CC249 displays an ultra red surface characteristic of a dynamically Cold Classical trans-Neptunian object.

We show that 'Oumuamua's excited spin could be in a high-energy long axis mode (LAM) state, which implies that its shape could be far from the highly elongated shape found in previous studies. CLEAN and ANOVA algorithms are used to analyze 'Oumuamua's lightcurve using 818 observations over 29.3. days. Two fundamental periodicities are found at frequencies (2.77 +/- 0.11) and (6.42 +/- 0.18). cycles/day, corresponding to (8.67 +/- 0.34) hr and (3.74 +/- 0.11) hr, respectively. The phased data show that the lightcurve does not repeat in a simple manner, but approximately shows a double minimum at 2.77. cycles/day and a single minimum at 6.42. cycles/day. 'Oumuamua could be spinning in either the LAM or short axis mode (SAM). For both, the long axis precesses around the total angular momentum vector with an average period of (8.67 +/- 0.34) hr. For the three LAMs we have found, the possible rotation periods around the long axis are 6.58, 13.15, or 54.48 hr, with 54.48 hr being the most likely. 'Oumuamua may also be nutating with respective periods of half of these values. We have also found two possible SAM states where 'Oumuamua oscillates around the long axis with possible periods at 13.15 and 54.48 hr. In this case any nutation occurs with the same periods. Determination of the spin state, the amplitude of the nutation, the direction of the total angular momentum vector (TAMV), and the average total spin period may be possible with a direct model fit to the lightcurve. We find that 'Oumuamua is "cigar-shaped," if close to its lowest rotational energy, and an extremely oblate spheroid if close to its highest energy state.

We identify new Y- and T-type brown dwarfs from the WISE All Sky data release using images obtained in filters that divide the traditional near-infrared H and J bands into two halves-specifically CH(4)s and CH(4)l in the H and J2, and J3 in the J. This proves to be very effective at identifying cool brown dwarfs via the detection of their methane absorption, as well as providing preliminary classification using methane colors and WISE -to-near-infrared colors. New and updated calibrations between T/Y spectral types and CH(4)s-CH(4)l J3-W2, and CH(4)s-W2 colors are derived, producing classification estimates good to a few spectral sub-types. We present photometry for a large sample of T and Y dwarfs in these filters, together with spectroscopy for 23 new ultra-cool dwarfs-2 Y dwarfs and 21 T dwarfs. We identify a further 8 new cool brown dwarfs, which we have high confidence are T dwarfs based on their methane photometry. We find that, for objects observed on a 4 m class telescope at J-band magnitudes of similar to 20 or brighter, CH(4)s-CH(4)l is the more powerful color for detecting objects and then estimating spectral types. Due to the lower sky background in the J-band, the J3 and J2 bands are more useful for identifying fainter cool dwarfs at J greater than or similar to 22. The J3-J2 color is poor at estimating spectral types. But fortunately, once J3-J2 confirms that an object is a cool dwarf, the J3-W2 color is very effective at estimating approximate spectral types.