Thermal observations of MUSES-C mission target (25143) 1998 SF ^*

¹ National Astronomical Observatory, 2-21-1 Osawa, Mitaka, Japan e-mail: t.sekiguchi@nao.ac.jp
² European Southern Observatory (ESO), Alonso de Cordova 3107, Vitacura, Santiago, Chile e-mail: hboehnha@eso.org, ohainaut@eso.org
³ Institute of Space and Astronautical Science (ISAS), 3-1-1 Yoshinodai, Sagamihara, Kanagawa, Japan e-mail: abe@planeta.sci.isas.ac.jp; hasegawa@planeta.sci.isas.ac.jp
⁴ School of Science, The University of Tokyo, Department of Astronomy, Bunkyo, Tokyo e-mail: budydr@cc.nao.ac.jp

Corresponding author: T. Sekiguchi, t.sekiguchi@nao.ac.jp

Received: 2 April 2001
Accepted: 25 September 2002

Abstract

We present thermal observations of MUSES-C mission target, (25143) 1998 SF₃₆. The mid-IR radiation in the N-band (11.9 μm) was measured using the ESO 3.6 m telescope with TIMMI2. Assuming the Standard Thermal Model and combining the thermal flux in the N-band with the time-resolved absolute magnitude in optical, the derived diameter and the geometric albedo are 0.35 (±0.03) km and 0.23 (+0.07, -0.05), respectively. While these values are model-dependent, we conclude that this Apollo class asteroid is of small size and its albedo is consistent with spectroscopic classification as an S-type asteroid.