- the observations are more convenient (especially
with slow motion stars)
- the set up of the instrument has a better stability,
since there is no need for the observer to touch
the micrometer during the tracking of the star.
7 Acknowledgement
The writer wishes to thank Mr. J. Lock for design
ing the electronical part, and Mr. C. de Vries and
Mr. D. L. F. van Loon for carrying out the observa
tions with great care and ability.
Errors of this magnitude with any universal theod
olite can be neglected. Also in the determination
of Laplace azimuths where the accuracy required is
usually about 0."3, errors of this magnitude are
insignificant [2], [12], Consequently, a very impor
tant conclusion can be drawn from this investiga
tion without applying any statistical test, i.e. that
star observations, carried out with a motor-micro
meter, are not influenced by the observer's personal
error.
It must be emphasized that the personal error, as
defined here, is a timing error, which should not be
confused with the so-called bisection error, another
kind of systematic pointing error. The bisection
error is eliminated from the observations with the
artificial star by taking the mean value of two
transits in opposite direction. Fortunately we have
a similar case with star observations when the
instrument used has a broken telescope. Taking the
observations in two positions of the instrument, the
bisection error is also eliminated.
6 Conclusion
Applying a micromotor as an attachment for
driving the self-recording micrometer of an universal
theodolite, like the DKM 3A, gives a number of
improvements, which may be summarized as follows
- the observations are practically free of personal
error
- compared with those made with a manually
operated micrometer the accuracy of the observa
tions is about 25% better
Corrections for the personal error
Observer A
3
ATp 0*028-C?OII X (straight line)
ATp= -O*O59+dl0e3X-OSO23X2 (parabola)
Fig. 5
Corrections tor the personal error
Observer B
ATf, - C?024-<?0I9X (straight line)
ATp --0S025*cfo3eJf-(#OI3X2 (parabola)
Fig. 6
References
1. Askania-Werke: Beschreibung des elektronischen Regis-
triermikrometers fiir das Passage-Instrument AP 70.
Berlin 1959.
2. G. J. Husti, The twin Laplace point Ubachsberg-
Tongeren, applying the Black method. Netherlands
Geodetic Commission, New series, Vol. 4, Nr. 1, 1971.
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report, Laboratorium voor Geodesie, Delft, 1972.
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kunde, Band Ha, Geodatische Astronomie, 1968.
5. W. Lorch, Untersuchungen iiber die personlichen Fehler
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6. H. Müller, Astronomische Orts-, Zeit- und Azimut-
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1971 von Kern Co. AG, Aarau, Schweiz.
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1962.
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Zeitschrift fiir Vermessungswesen, biz. 173, 1957.
13. H. Struve, Ober die Verbindung eines Uhrwerks mit dem
unpersönlichen Mikrometer von Repsold. Astronomische
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ngt 73
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