How do you read a sextant micrometer?
How do you read a sextant micrometer?
Reading the sextant is very simple:
- Degrees are read directly from the graduated arc opposite the index mark on the index arm.
- Minutes are read from the micrometer drum opposite the vernier index mark.
- Seconds are read from the vernier where one of the vernier graduations lines up with one of the. micrometer graduations.
What is a drum sextant?
Ideal for commercial sailing use, this Freiberger Drum Sextant is a traditional instrument used for celestial position navigation at sea. The optimal amount of brightness through the sextants optical light paths is controlled by means of swing in graded filters 4 for the index and 3 for the horizon mirrors.
What is frame of sextant?
A sextant is shaped in the form of a sector (60 degrees or 1/6th of a circle). It is the reason the navigational instrument is called a Sextant (Latin word for 1/6th is Sextans). The sector-shaped part is called the frame.
What is micrometer drum of sextant?
MICROMETER DRUM: Rotates To Make Fine Adjustments When Measuring Angles And Indicates Minutes Of A Degree Of Angle. It Is Attached To The Lower End Of The Index Arm. One Complete Rotation Moves The Index Arm 1° Along The Arc Scale. The Drum Has 60 Graduations, Each Representing1′ Of Arc.
What is the purpose of Coloured glass in sextant?
The vernier enables angles to be read to 10 seconds and the range of the scale is such as to enable angles up to 120 to be measured. The instrument is also fitted with filters, or dark-coloured glasses, which can be swung into position when needed, and are generally used for solar observations.
How do you use a sextant?
To use a sextant to find the angle of elevation of an object, you’ll need to know your elevation above sea level. Sight the horizon by looking through the horizon mirror, then move the sextant’s index arm until the object you’re trying to find is also visible on the horizon.
Can you use a sextant during the day?
Horizontal sextant angles can usually be taken any time during the day or night. During the day, you can measure the horizontal angle between two visible objects. The most important thing is to be able to positively identify the objects that you are measuring so that you can plot them accurately on your chart.
How does a micrometer drum sextant work?
MICROMETER DRUM SEXTANT A marine sextant providing a precise reading by means of a micrometer drum attached to the index arm, and having an endless tangent screw for controlling the position of the index arm. The micrometer drum may include a vernier to enable a more precise reading. On a vernier sextant the vernier is directly on the arc.
What is a vernier sextant micrometer?
The micrometer drum may include a vernier to enable a more precise reading. On a vernier sextant the vernier is directly on the arc. Pertaining to an object or structure in true vertical position as determined by a plumb bob.
What is an index mirror on a sextant?
INDEX MIRROR: Is A Piece Of Silvered Plate Glass Mounted On The Index Arm, Perpendicular To The Plane Of The Instrument, With The Center Of The Reflecting Surface Directly Over The Pivot Of The Index Arm. INDEX SHADES: Colored Transparent Substances Are Mounted On The Sextant’s Frame In Front Of The Index Mirror And Horizon Glass.
What are the parts of a sextant?
Parts of the sextant. The frame. The handle. The telescope or monocle. The rising piece. The arc. The index arm. The clamp. The worm and rack.
