Reduction of CCD observations of visual binaries using the “Tepui” function as PSF C. Abad, J. A. Docobo, V. Lanchares, J. F. Lahulla, P. Abelleira, J. Blanco and C. Alvarez A&A, 416 2 (2004) 811-814 Published online: 27 February 2004 DOI: 10.1051/0004-6361:20031715