  We describe a new iteration method to estimate asteroid coordinates, which is
based on the subpixel Gaussian model of a discrete object image. The method
operates by continuous parameters (asteroid coordinates) in a discrete
observational space (the set of pixels potential) of the CCD frame. In this
model, a kind of the coordinate distribution of the photons hitting a pixel of
the CCD frame is known a priori, while the associated parameters are determined
from a real digital object image. The developed method, being more flexible in
adapting to any form of the object image, has a high measurement accuracy along
with a low calculating complexity due to a maximum likelihood procedure, which
is implemented to obtain the best fit instead of a least-squares method and
Levenberg-Marquardt algorithm for the minimisation of the quadratic form.
  Since 2010, the method was tested as the basis of our CoLiTec (Collection
Light Technology) software, which has been installed at several observatories
of the world with the aim of automatic discoveries of asteroids and comets on a
set of CCD frames. As the result, four comets (C/2010 X1 (Elenin), P/2011
NO1(Elenin), C/2012 S1 (ISON), and P/2013 V3 (Nevski)) as well as more than
1500 small Solar System bodies (including five NEOs, 21 Trojan asteroids of
Jupiter, and one Centaur object) were discovered. We discuss these results that
allowed us to compare the accuracy parameters of a new method and confirm its
efficiency.
  In 2014, the CoLiTec software was recommended to all members of the
Gaia-FUN-SSO network for analysing observations as a tool to detect faint
moving objects in frames.
