The study of minor planets is motivated both by fundamental science of Solar system origins (some of these bodies contain the most pristine materials from the early ages of the planetary nebula) and by practical reasons concerning space exploration and impact frequency with Earth. Among minor bodies, near-Earth asteroids are a particularly important group: these objects are nearby the Earth's orbit and they represent both resources and hazards to humans. This is the case of 2014 JO 25. The encounter of this potentially hazardous asteroid with the Earth at 0.011 75 au on 2017 April 19 was a good opportunity to study its properties through photometric and spectral analyses. The work we present here has been carried out thanks to a worldwide observational campaign that included time-series photometry and spectroscopy in the visible and near-infrared wavelengths. The optical images for photometric analysis were collected at different phase angles using small telescopes (<0.5 m) and medium telescopes (from 0.6 to 1.5 m). Spectral analysis was performed by 2-4 m telescopes. The light curve of 2014 JO 25 indicates a synodic rotational period of 4.5286 ± 0.0004 h. Although rotational period had been previously obtained by other authors, this work confirms it with a better accuracy. The obtained reflectance spectrum of this asteroid indicates that it belongs to the S-complex and its surface is most likely composed of a mixture of pyroxenes and olivine. From the comparison of its spectrum to those of meteorite samples, as well as from the wavelength position of the first absorption band (close to 0.9 μm), we suggest that this asteroid might contain a large fraction of low-calcium pyroxene and, tentatively, some amounts of metal.© 2018 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society.

J. Licandro (JL), M. Serra-Ricart (MSR), O. Vaduvescu (OV), M. Popescu (MP), and J. de Leon (JdL) acknowledge support from the AYA2015-67772-R project (MINECO, Spain). JdL also acknowledges support from from MINECO under the 2015 Severo Ochoa Program SEV-2015-0548. The Isaac Newton Telescope and its service mode are operated on the island of La Palma by the Isaac Newton Group of Telescopes in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias. The work of MP was also been supported by a grant of the Romanian National Authority for Scientific Research - UEFISCDI, project number PN-II-RU-TE-2014-4-2199. The research leading to these results has received funding from the European Union's Horizon 2020 Research and Innovation Programme, under Grant Agreement No. 687378. We thank E. Molinari for allocation of Director's Discretionary Time at the Telescopio Nazionale Galileo. The work by P. Pravec was supported by the Grant Agency of the Czech Republic, Grant 17-00774S. Observations at CS3 and continued support of the asteroid light-curve data base (LCDB; Warner et al. 2009) are supported by NASA grant 80NSSC18K0851. This paper is partially based on data taken at the 0.77 m La Hita telescope, which is jointly operated by the Instituto de Astrofisica de Andalucia-CSIC and Astrohita. Blue Mountains Observatory is supported by the 2015 Shoemaker NEO grant.

Peer Reviewed