| Summary: | The work on the mass search for asteroids
on astroplate images and the determination of their coordi-
nates was begun in 2016. The basis for current search was
the processing results of digitized photographic plates and
films obtained at the observatory in Baldone in 1967-1993.
Observations with a single exposure in different spectral
bands were carried out using the 1.2m Schmidt telescope in
Baldone. We used all observations in the U Johnson's spec-
tral band (on plates) and significant part of them in V band
(on films). Photometric band U was realized by combining
emulsion ORWO Zu1 (Zu2 or Zu21 or Kodak 103aO or
IIaO) with UG1 filter. For films with A600 emulsion and
filter ZS17 a photometric band V was implemented.
Based on the results of digital processing about 300 U-
plates and more than 1460 V-films, a preliminary catalog
of 1700 asteroid positions was compiled. Among the ob-
jects in this catalog are asteroids of particular interest.
These include the distant objects (136108) Haumea and
(136472) Makemake and some Main belt asteroids, the
positions of which were fixed on the plates many years
before their own discoveries.
All observed positions of asteroids were compared with
ephemeris DE431. An analysis of the convergence of the
observed positions with their theoretical data for different
spectral bands showed that the observations on V-films
are better consistent with theory.
However, the internal accuracy of determining coordi-
nates from U-plates, on the contrary, is higher than from
V-films. This discrepancy is especially noticeable for right
ascension, when the root-mean-square errors on V-films
can reach values exceeding 1.8 arc seconds. These signifi-
cant errors are a consequence of the curvature unevenness
of the film surface during scanning
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