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%TCIDATA{Created=Fri Nov 28 15:08:28 2003}
%TCIDATA{LastRevised=Fri Nov 28 15:10:13 2003}
%TCIDATA{Language=American English}

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\begin{document}
\paperID{P6-2}	%%% Added FO
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\title{Images analysis in Asteroid and Satellites Astrometry}

\author{Alvaro L\'{o}pez Garc\'\i a}
\affil {Astronomical Observatory and Astronomy Department, University of
Valencia}


\author{Jose A. Mora\~{n}o}
\affil {Astronomical Observatory. University of Valencia}

\contact{Jose A. Morano}	% Added FO
\email{Alvaro.Lopez@uv.es}	% Added FO
\paindex{Lopez Garcia@L\'{o}pez Garc\'\i a, A.}	% Added FO
\aindex{Morano@Mora\~no, J. A.}	% Added FO
\authormark{L\'{o}pez Garc\'\i a \& Mora\~{n}o}		% Added FO

\begin{abstract}
At Astronomical Observatory of Valencia University (OAUV), CCD observations
of asteroids and big planets satellites are obtained since 2001 with a big
format camera and several telescopes.

Software has been developed, including accurate ephemerids calculation,
stellar maps presentation, automatic measuring and reduction process of film
plates and CCD frames.

Software for special conditions is under development, including distorted
images from differential tracking and images with spikes. Treatment of
regular nets on old plates (`Carte du Ciel') is under development. Software
for comparison of single and overlapped CCD fields obtained at different
epochs has been developed.
\end{abstract}

\section{Introduction}

CCD observations of asteroids and big planets are obtained at Valencia
Observatory (OAUV) since 2001 with two telescopes of 30 cm. and 3 meters
focal length and a CCD camera CCD AP10 of big size (2048 x 2048 pixels of 14
microns), getting fields of 30' by 30'. A new telescope $60$ $cm$ wide ($F8$%
) with altacimutal mounting, is operative since 2003. It will be used to
astrophysical observations and to astrometry of solar system faint objects.

Automatic techniques for measurement of plates, developed at OAUV since
1990, have been extended to detection and measuring of objects of CCD frames.

Reference stars are got from several dense catalogues. For each image a
`data file' is obtained, containing field information and catalogue stars in
and around field region. Field measurement is make with VisualBasic 5.0
algorithms, with images on BMP format.

\section{Observation of asteroids and satellites}

Small distance of Uranus and Neptune satellites from planet needs maximum
resolution of CCD images $(2048\times 2048$ pixels$).$ Results improve with
a red filter that dims blue color of planet. Special algorithm for detection
and separation of satellite images has been developed.

We have developed algorithms for several kinds of observations, including
ephemerids calculation, stellar maps presentation, measuring and reduction
of CCD fields and residuals calculation for asteroids observations.

In satellites work, ephemerids are obtained with ERA software (Krasinsky \&
Vasilyev 2001), provided by Applied Astronomy Institute of St.Petersburg
(Russia). CCD field size allows this kind of observations every day.

\section{Algorithm for asteroids and satellites astrometry}

The selected image is charged if `data file' exists. Measurement can be done
in `automatic' or `manual' way. Detection process includes algorithms for
distorted images. After images measurement in CCD field, catalogue stars are
identified and adjusted with images. Asteroid image is selected manually and
coordinates $\alpha $, $\delta $ and magnitude are obtained. Process for
satellites is similar and all main satellites can be selected for each
planet (L\'{o}pez et al. 2001).

\iffalse %%% BAD VERSION
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Figura 1. Etapa final de la identificaci\'{o}n de asteroides}}{}{P6-2_f1}{%
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\begin{figure}
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  \caption[]{Final step of the asteroid identification}
  \label{P6-2:f1}
\end{figure}
\fi

\section{Fields comparison}

Algorithms for individual and `mosaic' fields comparison has been developed,
allowing the search and detection of objects with different positions or
brightness (new asteroids, nova stars, variable stars).

In first case, each field is analyzed automatically, adding manually stars
not identified. For comparison, two similar triangles are found and field
images superposed for blinking. If identification is not correct, blinking
shows big differences and triangles must by chosen manually. Comparison
field is fitted to the reference one by rotation and translation of image
pixels.

\section{Fields overlapping and comparison}

In this case two `field mosaics' of $4\times 4$ `reference images' ($A$) and
`working images' ($C$) are constructed. To do that, linking of adjacent
fields allow to overlap them in order to obtain a single mosaic image for ($%
A $) and ($C$). Comparison of mosaic images is done by hand blinking. If it
shows a bad fitting, images of three object in both mosaics are selected and
image ($C$) is fitted to image ($A$) by rotation and translation..

\section{Special algorithms}

Algorithms for analysis of peculiar images, as obtained in differential
motion, spikes shown by bright images of telescopes and existence of
reticula in old plates (Carte du Ciel).

In differential motion of crowded fields plates, distortion of images and
partial overlapping increase difficulties of algorithm. After detection of a
complex image, contour is obtained and spurious images are eliminated.

For every group a sequential separation process is applied. Gaussian model
with two axis is fitted to each object and is substracted from its image
before continuing with the next one.

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\else	%%% CORRECTED FO
\begin{figure}
  \epsscale{0.80}
  \plotone{P6-2_f2.eps}
  \caption[]{Separation process of close images with differential motion}
  \label{P6-2:f2}
\end{figure}
\fi

Spikes joined to reflectors images and reticula of `Carte du Ciel' plates
need a previous elimination before applying standard measuring algorithms.
In both cases a `dirt' field image produces many `ghost' objects. Our
algorithm for spikes elimination is rather efficient (L\'{o}pez \& Mora\~{n}%
o 2003).

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"XNP";}}
\else	%%% CORRECTED FO
\begin{figure}
  \epsscale{0.80}
  \plotone{P6-2_f3.eps}
  \caption[]{Reticule elimination in Carte du Ciel plates}
  \label{P6-2:f3}
\end{figure}
\fi

We are developing algorithms for `Carte du Ciel' plates full analysis,
without using lists of objects detected in previous studies. Bad quality of
some plate zones increases complexity of this analysis.

\section{Conclusions}

We have developed a program for systematic observations of asteroids and
satellites,that is carried on with several telescopes and CCD sensors at
OAUV.

Several problems associated to astronomical images analysis (spikes
elimination, differential tracking of crowded fields, reticula of `Carte du
Ciel' plates, etc.), have been faced with good results.

Our projects for next year include astrometry and photometry of faint
asteroids, using 60 cm. telescope.

\begin{references}
\reference Krasinsky, G.A., \& Vasilyev, M.V., \ 2001, ERA handbook.
\reference L\'{o}pez, A., Mora\~{n}o, J.A., Yagudin, L.,  \& Flores, A. \ 2001, Photographic and CCD Observations of Minor Planets from Valencia Observatory, Ceres 2001.
\reference L\'{o}pez Garc\'\i a, A.\& Mora\~{n}o, J.A. \ 2003, Observaciones CCD de asteroides y planetas, JORNADAS CIENTIFICAS 250 A\~{N}OS DE ASTRONOMIA EN ESPA\~{N}A.
\end{references}

\end{document}
