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In our study, we used the convex inversion thermophysical models (CITPM) by Durech et al. [1] to constrain asteroid's shape model and parameters, including thermal inertia, geometric albedo, and surface roughness simultaneously from optical and infrared data. We collected size and spin state as input parameters from lightcurve inversion and published results, and they were also improved in our running. Using the latest optical photometry data from ground-based big surveys and long-term thermal observations at different wavelengths from three infrared space missions: IRAS, AKARI, and WISE. By comparing our results with a large set of thermal properties of asteroids by Hung et al. [2] and asteroid models in DAMIT [3], we were not only able to optimize thousands of asteroids' parameters but also enlarge the database of asteroid models. In our future work, we plan to collect more asteroids' photometry data from a variety of surveys, especially from Gaia DR3 which will be released in June 2022, and the first light of LSST (Vera C. Rubin Observatory) is expected in 2023. The new parameters of asteroids will be useful to analyze asteroid population distribution and the physical mechanism behind it. References [1] Durech et al., 2017, Astronomy & Astrophysics 604, A27. [2] Hung et al., 2022, The Planetary Science Journal, 3, 56. [3] Durech et al., 2010, Astronomy & Astrophysics 513, A46.

We present time-resolved visible spectrophotometry of 2020 CD₃, the second known minimoon. The spectrophotometry was taken with the Keck I/Low Resolution Imaging Spectrometer between wavelengths 434 and 912 nm in the B, g, V, R, I, and RG850 filters as it was leaving the Earth–Moon system on 2020 March 23 UTC. The spectrum of 2020 CD₃ resembles V-type asteroids and some lunar rock samples with a 434–761 nm reddish slope of ~18%/100 nm (g–r = 0.62 ± 0.08 and r–i = 0.21 ± 0.06) with an absorption band at ~900 nm corresponding to i–z = −0.54 ± 0.10. Combining our measured H of 31.9 ± 0.1 with an albedo of 0.35 typical for V-type asteroids, we determine 2020 CD₃'s diameter to be ~0.9 ± 0.1 m, making it the first minimoon and one of the smallest asteroids to be spectrally studied. We use our time-series photometry to detect significant periodic light-curve variations with a period of ~573 s and amplitude of ~1. In addition, we extend the observational arc of 2020 CD₃ to 37 days, to 2020 March 23 UTC. From the improved orbital solution for 2020 CD₃, we estimate the likely duration of its capture to be ~2 yr and the nongravitational perturbation on its orbit due to radiation pressure with an area-to-mass ratio of (6.9 ± 2.4) × 10⁻⁴ m² kg⁻¹ implying a density of 2.3 ± 0.8 g cm⁻³, broadly compatible with other meter-scale asteroids and lunar rock. We searched for prediscovery detections of 2020 CD₃ in the Zwicky Transient Facility archive as far back as 2018 October but were unable to locate any positive detections.

Two high-cadence surveys aiming for rotation period measurements of asteroids have been conducted in 2019 January and October using the Zwicky Transient Facility. From the surveys, 25 large superfast rotators (SFRs) were discovered and they are all main-belt asteroids (MBAs), except for one Mars crosser. These large SFRs have a diameter ranging from 0.43 to 7.87 km and a rotation period between 0.48 and 1.95 hr. Considering their diameters and fast rotations, they cannot be explained by rubble-pile structure unless using extraordinary high bulk densities. Cohesion, if available, can conserve these large SFRs. The estimated cohesion for these large SFRs could be up to thousands of pascals, much higher than the currently estimated cohesion for asteroids and that generated by the regolith of Moon and Mars. Such high-level cohesion can be produced from fine-grain regolith, like clay. However, the availability of such fine-grain regolith for asteroids is still unknown. Although the possibility of these large SFRs being large monolithic objects cannot be ruled out, this scenario is very unlikely given that the timescale of disruptive impact for MBAs in a similar diameter range is 107–108 yr.

All authors: Kasliwal, Mansi M.; Anand, Shreya; Ahumada, Tomás; Stein, Robert; Carracedo, Ana Sagués; Andreoni, Igor; Coughlin, Michael W.; Singer, Leo P.; Kool, Erik C.; De, Kishalay; Kumar, Harsh; AlMualla, Mouza; Yao, Yuhan; Bulla, Mattia; Dobie, Dougal; Reusch, Simeon; Perley, Daniel A.; Cenko, S. Bradley; Bhalerao, Varun; Kaplan, David L.; Sollerman, Jesper; Goobar, Ariel; Copperwheat, Christopher M.; Bellm, Eric C.; Anupama, G. C.; Corsi, Alessandra; Nissanke, Samaya; Agudo, Iván; Bagdasaryan, Ashot; Barway, Sudhanshu; Belicki, Justin; Bloom, Joshua S.; Bolin, Bryce; Buckley, David A. H.; Burdge, Kevin B.; Burruss, Rick; Caballero-García, Maria D.; Cannella, Chris; Castro-Tirado, Alberto J.; Cook, David O.; Cooke, Jeff; Cunningham, Virginia; Dahiwale, Aishwarya; Deshmukh, Kunal; Dichiara, Simone; Duev, Dmitry A.; Dutta, Anirban; Feeney, Michael; Franckowiak, Anna; Frederick, Sara; Fremling, Christoffer; Gal-Yam, Avishay; Gatkine, Pradip; Ghosh, Shaon; Goldstein, Daniel A.; Golkhou, V. Zach; Graham, Matthew J.; Graham, Melissa L.; Hankins, Matthew J.; Helou, George; Hu, Youdong; Ip, Wing-Huen; Jaodand, Amruta; Karambelkar, Viraj; Kong, Albert K. H.; Kowalski, Marek; Khandagale, Maitreya; Kulkarni, S. R.; Kumar, Brajesh; Laher, Russ R.; Li, K. L.; Mahabal, Ashish; Masci, Frank J.; Miller, Adam A.; Mogotsi, Moses; Mohite, Siddharth; Mooley, Kunal; Mroz, Przemek; Newman, Jeffrey A.; Ngeow, Chow-Choong; Oates, Samantha R.; Patil, Atharva Sunil; Pandey, Shashi B.; Pavana, M.; Pian, Elena; Riddle, Reed; Sánchez-Ramírez, Rubén; Sharma, Yashvi; Singh, Avinash; Smith, Roger; Soumagnac, Maayane T.; Taggart, Kirsty; Tan, Hanjie; Tzanidakis, Anastasios; Troja, Eleonora; Valeev, Azamat F.; Walters, Richard; Waratkar, Gaurav; Webb, Sara; Yu, Po-Chieh; Zhang, Bin-Bin; Zhou, Rongpu; Zolkower, Jeffry, We present a systematic search for optical counterparts to 13 gravitational wave (GW) triggers involving at least one neutron star during LIGO/Virgo's third observing run (O3). We searched binary neutron star (BNS) and neutron star black hole (NSBH) merger localizations with the Zwicky Transient Facility (ZTF) and undertook follow-up with the Global Relay of Observatories Watching Transients Happen (GROWTH) collaboration. The GW triggers had a median localization area of 4480 deg2, a median distance of 267 Mpc, and false-alarm rates ranging from 1.5 to 10-25 yr-1. The ZTF coverage in the g and r bands had a median enclosed probability of 39%, median depth of 20.8 mag, and median time lag between merger and the start of observations of 1.5 hr. The O3 follow-up by the GROWTH team comprised 340 UltraViolet/Optical/InfraRed (UVOIR) photometric points, 64 OIR spectra, and three radio images using 17 different telescopes. We find no promising kilonovae (radioactivity-powered counterparts), and we show how to convert the upper limits to constrain the underlying kilonova luminosity function. Initially, we assume that all GW triggers are bona fide astrophysical events regardless of false-alarm rate and that kilonovae accompanying BNS and NSBH mergers are drawn from a common population; later, we relax these assumptions. Assuming that all kilonovae are at least as luminous as the discovery magnitude of GW170817 (-16.1 mag), we calculate that our joint probability of detecting zero kilonovae is only 4.2%. If we assume that all kilonovae are brighter than-16.6 mag (the extrapolated peak magnitude of GW170817) and fade at a rate of 1 mag day-1 (similar to GW170817), the joint probability of zero detections is 7%. If we separate the NSBH and BNS populations based on the online classifications, the joint probability of zero detections, assuming all kilonovae are brighter than-16.6 mag, is 9.7% for NSBH and 7.9% for BNS mergers. Moreover, no more than 10-4, or φ > 30° to be consistent with our limits. We look forward to searches in the fourth GW observing run; even 17 neutron star mergers with only 50% coverage to a depth of-16 mag would constrain the maximum fraction of bright kilonovae to, This work was supported by the Global Relay of Observatories Watching Transients Happen (GROWTH) project, funded by the National Science Foundation under PIRE grant No. 1545949. GROWTH is a collaborative project among the California Institute of Technology (USA), University of Maryland College Park (USA), University of Wisconsin Milwaukee (USA), Texas Tech University (USA), San Diego State University (USA), University of Washington (USA), Los Alamos National Laboratory (USA), Tokyo Institute of Technology (Japan), National Central University (Taiwan), Indian Institute of Astrophysics (India), Indian Institute of Technology Bombay (India), Weizmann Institute of Science (Israel), The Oskar Klein Centre at Stockholm University (Sweden), Humboldt University (Germany), Liverpool John Moores University (UK), and University of Sydney (Australia). Based on observations obtained with the Samuel Oschin Telescope 48 inch and the 60 inch telescope at the Palomar Observatory as part of the Zwicky Transient Facility project. The ZTF is supported by the National Science Foundation under grant No. AST-1440341 and a collaboration including Caltech, IPAC, the Weizmann Institute for Science, the Oskar Klein Center at Stockholm University, the University of Maryland, the University of Washington, Deutsches Elektronen-Synchrotron and Humboldt University, Los Alamos National Laboratories, the TANGO Consortium of Taiwan, the University of Wisconsin at Milwaukee, and Lawrence Berkeley National Laboratories. Operations are conducted by COO, IPAC, and UW. The ZTF forced photometry service was funded under Heising-Simons Foundation grant No. 12540303 (PI: Graham). The SED Machine is based upon work supported by the National Science Foundation under grant No. 1106171. The GROWTH-India telescope is a 70 cm telescope with a 0.7 degrees field of view, set up by the Indian Institute of Astrophysics and the Indian Institute of Technology Bombay with support from the Indo-US Science and Technology Forum (IUSSTF) and the Science and Engineering Research Board (SERB) of the Department of Science and Technology (DST), Government of India (https://sites.google.com/view/growthindia/). It is located at the Indian Astronomical Observatory (Hanle), operated by the Indian Institute of Astrophysics (IIA). The GROWTH-India project is supported by SERB and administered by IUSSTF under grant No. IUSSTF/PIRE Program/GROWTH/2015-16. This research has made use of the VizieR catalog access tool, CDS, Strasbourg, France (doi: 10.26093/cds/vizier). The original description of the VizieR service was published in A&AS 143, 23. These results made use of the Lowell Discovery Telescope (LDT) at Lowell Observatory. Lowell is a private, nonprofit institution dedicated to astrophysical research and public appreciation of astronomy and operates the LDT in partnership with Boston University, the University of Maryland, the University of Toledo, Northern Arizona University, and Yale University. The Large Monolithic Imager was built by Lowell Observatory using funds provided by the National Science Foundation (AST-1005313). The upgrade of the DeVeny optical spectrograph has been funded by a generous grant from John and Ginger Giovale and a grant from the Mt. Cuba Astronomical Foundation. The KPED team thanks the National Science Foundation and the National Optical Astronomical Observatory for making the Kitt Peak 2.1 m telescope available. We thank the observatory staff at Kitt Peak for their efforts to assist Robo-AO KP operations. The KPED team thanks the National Science Foundation, the National Optical Astronomical Observatory, the Caltech Space Innovation Council, and the Murty family for support in the building and operation of KPED. In addition, they thank the CHIMERA project for use of the Electron Multiplying CCD (EMCCD). The Liverpool Telescope is operated on the island of La Palma by Liverpool John Moores University in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias with financial support from the UK Science and Technology Facilities Council. Some spectroscopic observations were obtained with the Southern African Large Telescope (SALT). The Photometric Redshifts for the Legacy Surveys (PRLS) catalog used in this paper was produced thanks to funding from the U.S. Department of Energy Office of Science, Office of High Energy Physics, via grant DE-SC0007914. This publication has made use of data collected at Lulin Observatory, partly supported by MoST grant 108-2112-M-008-001. Based on observations made with the Gran Telescopio Canarias (GTC), installed at the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias on the island of La Palma. M.M.K. acknowledges generous support from the David and Lucille Packard Foundation. M.W.C. acknowledges support from the National Science Foundation with grant No. PHY-2010970. A.G. and J.S. acknowledge support from the Knut and Alice Wallenberg Foundation and GREAT research environment grant 2016-06012, funded by the Swedish Research Council. Some of the work by D.A.P. was performed at the Aspen Center for Physics, which is supported by National Science Foundation grant PHY-1607611. D.A.P. was partially supported by a grant from the Simons Foundation. H.K. thanks the LSSTC Data Science Fellowship Program, which is funded by LSSTC, NSF Cybertraining Grant 1829740, the Brinson Foundation, and the Moore Foundation; his participation in the program has benefited this work. This work has been supported by the Spanish Science Ministry Centro de Excelencia Severo Ochoa Program under grant SEV-2017-0709. A.J.C.T. acknowledges support from the Junta de Andalucia (Project P07-TIC-03094) and Spanish Ministry Projects AYA2012-39727-C03-01, AYA2015-71718R, and PID-019-109974RB-I00. V.A.F. was supported by grant RFBR 19-02-00432. I.A. acknowledges support by a Ramon y Cajal grant (RYC-2013-14511) of the Ministerio de Ciencia, Innovacion, y Universidades (MICIU) of Spain. He also acknowledges financial support from MCIU through grant AYA2016-80889-P. A.A.M. is funded by the Large Synoptic Survey Telescope Corporation, the Brinson Foundation, and the Moore Foundation in support of the LSSTC Data Science Fellowship Program; he also receives support as a CIERA Fellow by the CIERA Postdoctoral Fellowship Program (Center for Interdisciplinary Exploration and Research in Astrophysics, Northwestern University). A.C. acknowledges support from the National Science Foundation with grant No. 1907975. W.-H.I., A. K., K.-L.L., C.-C.N., A.P., H.T., and P.-C.Y. acknowledge support from Ministry of Science and Technology (MoST) Taiwan grants 104-2923-M-008-004-MY5, 107-2119-M-008-012, 108-2628-M-007-005-RSP, and 108-2112-M-007-025-MY3. D.D. is supported by an Australian Government Research Training Program Scholarship. S.A. is supported by the GROWTH project, funded by the National Science Foundation under PIRE grant No. 1545949. A.S.C. is supported by GREAT research environment grant 2016-06012, funded by the Swedish Research Council. E.C.K. acknowledges support from the G.R.E.A.T. research environment and the Wenner-Gren Foundations. A.J.C.T. is thankful for fruitful discussions with J. Cepa, E. Fernandez-Garcia, J. A. Font, S. Jeong, A. Martin-Carrillo, A. M. Sintes, and S. Sokolov. D.A.H.B. acknowledges research support from the National Research Foundation of South Africa. S.B.P. and V.B. acknowledge BRICS grant No. "DST/IMRCD/BRICS/PilotCall1/ProFCheap/2017(G)" for part of the present work. J.S.B. was partially supported by a Gordon and Betty Moore Foundation Data-Driven Discovery grant and a grant from the National Science Foundation, "Conceptualization of a Scalable Cyberinfrastructure Center for Multimessenger Astrophysics."

We report on a multi-observatory campaign to examine asteroid 3200 Phaethon during its December 2017 close approach to Earth, in order to improve our measurements of its fundamental parameters, and to search for surface variations, cometary activity and fragmentation. The mean colors of Phaethon are B-V = 0.702 +/- 0.004, V-R = 0.309 +/- 0.003, R-I = 0.266 +/- 0.004, neutral to slightly blue, consistent with previous classifications of Phaethon as a F-type or B-type asteroid. Variations in Phaethon's B-V colors (but not V-R or R-I) with observer sub-latitude are seen and may be associated with craters observed by the Arecibo radar. High cadence photometry over phases from 20 to 100 degrees allows a fit to the values of the HG photometric parameters; H = 14.57 +/- 0.02, 13.63 +/- 0.02, 13.28 +/- 0.02, 13.07 +/- 0.02; G = 0.00 +/- 0.01, -0.09 +/- 0.01, -0.10 +/- 0.01, -0.08 +/- 0.01 in the BVRI filters respectively; the negative G values are consistent with other observations of F type asteroids. Light curve variations were seen that are also consistent with concavities reported by Arecibo, indicative of large craters on Phaethon's surface whose ejecta may be the source of the Geminid meteoroid stream. A search for gas/dust production set an upper limit of 0.06 +/- 0.02 kg/s when Phaethon was 1.449 AU from the Sun, and 0.2 +/- 0.1 kg/s at 1.067 AU. A search for meter-class fragments accompanying Phaethon did not find any whose on-sky motion was not also consistent with background main belt asteroids., Accepted by the Astronomical Journal, 15 pages, 8 figures, 1 animated figure

We describe ZStreak, a semi-real-time pipeline specialized in detecting small, fast-moving near-Earth asteroids (NEAs) that is currently operating on the data from the newly-commissioned Zwicky Transient Facility (ZTF) survey. Based on a prototype originally developed by Waszczak et al. (2017) for the Palomar Transient Factory (PTF), the predecessor of ZTF, ZStreak features an improved machine-learning model that can cope with the $10\times$ data rate increment between PTF and ZTF. Since its first discovery on 2018 February 5 (2018 CL), ZTF/ZStreak has discovered $45$ confirmed new NEAs over a total of 232 observable nights until 2018 December 31. Most of the discoveries are small NEAs, with diameters less than $\sim100$ m. By analyzing the discovery circumstances, we find that objects having the first to last detection time interval under 2 hr are at risk of being lost. We will further improve real-time follow-up capabilities, and work on suppressing false positives using deep learning., PASP in press

An accurate incipient localized faults diagnosis method is very helpful for preventing serious accidents of planetary gearboxes. Although useful, the ensemble empirical mode decomposition (EEMD) method still has some issues in selecting the effective intrinsic mode functions (IMFs). To overcome these issues, an improved encircled energy EEMD method (EE-EEMD) combined with the EEMD algorithm, mirror extending method, Teager energy operator demodulation method, and EE index selection method is presented to detect localized faults in the planet bearings, ring gear, planet gear, and sun gear of planetary gearboxes. The mirror extending method is applied to address the end extending issue of the EEMD method. The EE index is utilized to determine the effective IMFs from the EEMD method. The energy separation algorithm is used to calculate the instantaneous frequencies of the effective IMFs. The results from the EE index, kurtosis, and weight kurtosis selection methods are compared. The vibration signal models of the localized faults in the ring gear, planet gear, sun gear, planet bearing races, and planet bearing roller are used to illustrate the validity of the presented EE-EEMD method. An experimental investigation for a planetary gearbox considering a spall fault in the sun gear is conducted to validate the presented EE-EEMD method. It seems the presented EE-EEMD method can be utilized to detect localized faults in the components of planetary gearboxes.