Trans-Neptunian Objects Found in the First Four Years of the Dark Energy Survey
Smith, M.; Abbott, T. M. C.; Brooks, D.; Burke, D. L.; Carnero Rosell, A.; Carrasco Kind, M.; Castander, F. J.; da Costa, L. N.; Desai, S.; Diehl, H. T.; Doel, P.; Flaugher, B.; García-Bellido, J.; Gruen, D.; Gruendl, R. A.; Gschwend, J.; Gutierrez, G.; James, D. J.; Johnson, M. W. G.; Kuropatkin, N.; Maia, M. A. G.; Miquel, R.; Plazas, A. A.; Romer, A. K.; Rykoff, E. S.; Sanchez, E.; Scarpine, V.; Sevilla-Noarbe, I.; Sobreira, F.; Suchyta, E.; Swanson, M. E. C.; Tarle, G.; Walker, A. R.; DES Collaboration; Adams, Fred C.; Zhang, Y.; Hollowood, D. L.; Avila, S.; De Vicente, J.; March, M.; Paz-Chinchón, F.; Serrano, S.; Johnson, M. D.; Krause, E.; Everett, S.; Sako, Masao; Franson, Kyle; Brout, Dillon; Bernardinelli, Pedro H.; Bernstein, Gary M.; Liu, Tongtian; Saunders, William R.; Khain, Tali; Lin, Hsing Wen; Gerdes, David W.; Belyakov, Matthew; Somasundaram, Aditya Inada; Sharma, Lakshay; Locke, Jennifer; Becker, Juliette C.; Napier, Kevin; Markwardt, Larissa; Annis, James; Sánchez, C.; Wester, W.
United States, Chile, Spain, United Kingdom, Brazil, India
Abstract
We present a catalog of 316 trans-Neptunian bodies (TNOs) detected from the first four seasons ("Y4" data) of the Dark Energy Survey (DES). The survey covers a contiguous 5000 deg2 of the southern sky in the grizY optical/NIR filter set, with a typical TNO in this part of the sky being targeted by 25-30 Y4 exposures. This paper focuses on the methods used to detect these objects from the ≈60,000 Y4 exposures, a process made challenging by the absence of the few-hour repeat observations employed by TNO-optimized surveys. Newly developed techniques include: transient/moving object detection by comparison of single-epoch catalogs to catalogs of "stacked" images; quantified astrometric error from atmospheric turbulence; new software for detecting TNO linkages in a temporally sparse transient catalog, and for estimating the rate of spurious linkages; use of faint stars to determine the detection efficiency versus magnitude in all exposures. Final validation of the reality of linked orbits uses a new "sub-threshold confirmation" test, wherein we demand the object be detectable in a stack of the exposures in which the orbit indicates an object should be present, but was not individually detected. This catalog contains all validated TNOs which were detected on ≥6 unique nights in the Y4 data, and is complete to r ≲ 23.3 mag with virtually no dependence on orbital properties for bound TNOs at distance 30 au < d < 2500 au. The catalog includes 245 discoveries by DES, 139 not previously published. The final DES TNO catalog is expected to yield >0.3 mag more depth, and arcs of >4 yr for nearly all detections.