Alternative Methods; Finding The Position; Memory Foil - CASSENS & PLATH POLARIS Handhabung

Instructions
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Alternative Methods

There are two common methods of star sighting:
1. Adjust index shade glasses to diminish light transmission as mentioned above.
glasses have to be adjusted only to reduce brightness of reflections on the water. Face to the
direction of the celestial body. Observe the horizon through telescope and horizon mirror.
Move the alidade up and down (accidentally) until the image of the star appears. Now engage
the lever and carry out fine adjustment and proceed as mentioned above.
2. Adjust index shade glasses to diminish light transmission as mentioned above.
glasses have to be adjusted only to reduce brightness of reflections on the water. Precalculate
the star height and move the index arm to this angle. As the field of view of the telescope is 8°
the intended star can be found easily.

Finding the Position

The apparent height measured as written before has to be corrected before starting the
mathematical treatment. The corrections can be found in the nautical almanach. In addition, at the
moment of altitude measurement, the Greenwich time (world time or UTC) has to be filed. Both,
star height and UTC will give one line of position (LOP). The intercept of two or more LOPs will
give the true position, the FIX.
The mathematical procedure cannot be explained here. Refer to the relevant literature, like
"American Practical Navigator" by Nathaniel Bowditch et al., U.S. Defense Mapping Agency, or
others.

Memory Foil

At the sextant grip one will find a white foil. This is to note the measured sextant altitude with a
lead pencil. Take the sextant with the left hand at the frame so the right hand is free to write. Erase
the writing with your thumb.
Memory foil, use
lead pencil to note
the star altitude
POLARIS Sextant
Horizon shade
Horizon shade