Audited Supplier
Marine Nautical Sextant
Marine Nautical sextant is a kind of reflection type angular measuring optical instrument, chiefly used for measuring the altitude of celestial bodies to obtain a position in navigation. The VERTICAL ERROR, ERROR and INDEX ERROR of the instrument should be adjusted and predeter mined before use.
Application:
1.Measuring the altitude of celestial bodies to determine the position of the ship at sea.
2.Measuring the two horizontal angles between three known position land objects the ship.
3.location on chart by the help of a station pointer.
4.Measuring the vertical angle of a known altitude objection to obtain its distance.
Features:
1. Reasonable price and fine workmanship
2. Made of copper
3. IMPA Code: 370332
Type: | GLH-130-20 | GLH-130-40 | GLH-130-60 |
Measuring Range: | -5º to 130 º | -5º to 130 º | -5 º to 130 º |
Accuracy: | 20″ | 40″ | 60″ |
Readability: | 12″ | 12″ | 12″ |
Temperature Range: | -30°c to 50 °c | -30°c to 50 °c | -30 °c to 50 °c |
Telescope: | 3.5×20 | 3.5×40 | 3.5×60 |
Lamp Voltage: | 3V | 3V | 3V |
New Weight: | 1.2KG | 1.2KG | 1.2KG |
INSTRUMENT ADJUSTMENT
VERTICL ERROR - the index mirror is not normal to the instrument plane.
For adjusting, turn the index arm to arc graduation 30°-40°, now look down on the mirror so that the graduated arc and its reflected image are visible. If the reflected image is lower than the actual one, turn the adjusting screw clock wisely, graduated arc will coincide and appear to from a continuous line.
LATERAL ERROR - the horizon glass is not normal to the instrument plane.
For adjusting, mount the telescopes onto the sextant zero degree. Take a sight to a celestial object (the sun, moon or star) or a farther 1.5km distant object, if its reflected image is located at the right side of the direct image, turn the left side adjusting screw of the horizon glass clock wisely, vice versa, until these image are coincided completely.
INDEX ERROR - while the index arm reading is zero degree, but the index mirror is not parallel to the horizon glass.
The index error displays the zero error of a sextant, it does not influence the accuracy of an angle measurement if give it a correction , but it should be predetermined before a use.
