This gives Duende a geometric mean (spherical) diameter equivalent to . During the close approach, an observational campaign involving 5 different telescopes in 4 different observatories was carried on in order to get information on the physical properties of this NEO. Visible and near-Infrared photometry and visible spectroscopy were obtained at Gran Telescopio Canarias, Telescopio Nazionale Galileo and Calar Alto Observatory and put together. The classification using the M4AST online tool says this is an L-type asteroid. Those peculiar asteroids are characterized by a strongly reddish spectrum shortward of 0.8 μm, and a featureless flat spectrum longward of this, with little or no concave-up curvature related to a 1 μm silicon absorption band. Time-series photometry was also obtained in the Observatorio de La Hita () and Observatorio de Sierra Nevada during two consecutive nights (15–16 February 2013). All of this data were co-phased to build a lightcurve of the object. This lightcurve is double-peak and presents large variations in magnitude, implying a very elongated object, which is compatible with radar observations. The amplitude of the lightcurve yields an axial ratio that, together with the long axis of 40 m inferred from the radar images by Goldstone, results in an equivalent diameter of 18 m, much smaller than the estimations before the close-approach. The rotational period was precisely determined from the lightcurve obtaining a value of . This value is confirmed with an analysis of all the photometry of this objects reported to the Minor Planet Center. Using data pre and post close approach the authors find that the object suffered a spin-up during the event that decreased the rotational period from down to hours, which is compatible with the more accurate value estimated from the light-curve. The close approach to Earth reduced the orbital period of Duende from 368 days to 317 days, Its aphelion was reduced from 1.110 to 0.9917 AU, leaving it almost entirely inside Earth's orbit and perturbing it from the Apollo class to the Aten class of near-Earth asteroids. Its next close approach to Earth will be on 15 February 2046, when it will pass about from Earth. Based on 7 radar observations, the next close approach to Earth similar to the 2013 passage will be on 16 February 2123, when Duende will pass no closer than from the center of Earth. For the 2123 passage, the nominal pass will be from the center of the Moon and then from the center of Earth.