STEP 1
Determine the Ho and LHA of Aries.
STEP 2
The Polaris Tables are entered to find the three parts of the Polaris correction. I use the sample problem at the bottom of the table on page 275 to provide the format and I add this to my sight form. The entering argument for the tables is the LHA of Aries, 238-48.3'. The appropriate column is, therefore, last one, headed 230° - 239.
STEP 3
To find the ao part, the upper third of the table containing corrections for each integral degree of LHA from 230 to 239 is used with interpolation, if necessary to arrive at the ao correction corresponding to LHA of Aries 238° 48.3'. In this case, the tabulated ao value for LHA of Aries 238 is +1- 43.3' recording this +1- 43.3' correction on the form,
STEP 4
Now proceed to the middle third of the table, in the same column, to obtain the a1 part. The entering argument in the left margin is the tabulated latitude closest to the DR latitude, or 23 in this case. The corresponding a1 value is +0.6' which is recorded on the form.
STEP 5
The a2 part is obtained from the lower third of the table, staying in the same column, opposite the month of observation, July in this case. It is +1.0'. As a final step in finding the total correction to be applied to Ho, ao ,a1, and a2 are always added and the required - 1 °is a constantin this example, applying these corrections to Ho yields the desired latitude line, 24 19.5'N.
STEP 6
Staying in the last column, enter the Azimuth part of the table with your DR latitude 23" and extract the true azimuth of Polaris, in this case, 000.3° T. Then find the gyro error and deviation.
