2003IAUC.8056....2K

D. Kato and T. Nagata, Nagoya University, on behalf of the InfraRed Survey Facility (IRSF)/Simultaneous three-color InfraRed Imager for Unbiased Survey (SIRIUS) team of Nagoya University and the National Astronomical Observatory of Japan; T. Kato and M. Uemura, Kyoto University; and H. Yamaoka, Kyushu University, report on near-infrared (J, H, K_s) imaging of the field of the x-ray transient XTE J1720-318 (IAUC 8050) with the IRSF (which consists of the Nagoya-South African Astronomical Observatory 1.4-m telescope + SIRIUS) at Sutherland on Jan. 18.1 and 19.1 UT. A likely infrared counterpart was detected at R.A. = 17h19m59s.00, Decl. = -31o45'01".2 (equinox 2000.0; about 150 2MASS reference stars; rms error 0".2), located within 1".7 of the proposed radio counterpart (IAUC 8054). The new object is invisible on public 2MASS images; any definite identification would require further follow-up observations, since the brightness of the new object is close to the limiting magnitudes of the 2MASS survey. Magnitudes for the likely infrared counterpart of XTE J1720-318 are: Jan. 18.1, J = 16.73 ± 0.02, H = 15.91 ± 0.03, K_s = 15.31 ± 0.03; 19.1, 16.68 ± 0.02, 15.80 ± 0.03, 15.27 ± 0.05.