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measurement. (Circle Left and Circle Right refer to the position of the vertical circle housing
relative to the observer: See
The theodolite undergoes a rigorous magnetic hygiene inspection at Bartington Instruments
prior to fitting the probe. Any contamination is totally removed to guarantee complete magnetic
cleanliness. Optical and magnetic calibrations are also carried out prior to despatch.
5.1. Night Viewing
The scale illumination lamp unit supplied by Wild is unsuitable due to its magnetic signature.
The alternative, recommended and supplied by Bartington, is a chemiluminescent light stick.
These are approximately 47mm length x circa 6 mm diameter. Bend the light stick to activate it
and place between the theodolite mirror and window to provide illumination.
Note: Night adjusted vision responds to this level of illumination, but below freezing point
the illumination may become inadequate.
5.2. Steep Sighting Prisms
When performing steep angled telescopic observations or attempting to perform null mode
magnetic measurements for shallow angles of I, a pair of steep sighting prisms will be required.
These will extend the vertical-viewing angle from circa 40° to 18°.
There are two types of prism. The larger type fits the telescope eyepiece and results in an
inverted image. The smaller prism fits the scale eyepiece and results in a non-inverted image.
5.3. Objective Sun and Orange Filters
The orange filter can be used to eliminate glare, for example, when viewing a target.
Check frequently that the filter is reliably fitted to the telescope objective lens during
observations.
WARNING: Failure to check, fit and use the sun filter when performing solar observations
may cause irreparable damage to the user's eyes. Bartington Instruments can accept
NO liability for injuries resulting from solar observations, as we have no control over the
circumstances of use.
Note: The sun filter must be fitted when performing solar observations. It provides
an attenuation of above 1/100,000. Inspect the filter to ensure the free-floating silver
membrane is present and undamaged prior to use.
BARTINGTON INSTRUMENTS
Performing Observation of
Page 13 of 32
Declination.)
OM2020/5
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