Answers to a couple of questions from perceptive recipients :
1) Significance of shapes and borders for various data boxes:
a) Rounded ended boxes: these denote the data we provide from our observations.
b) Thin-bordered boxes denote intermediate calculation results which are used immediately, being added or subtracted from the running total as instructed (ie they will NOT need to be copied into a box elsewhere).
c) Non existent boxes (with vertical dividers only) denote "Corrections", which are found from the Sight Reduction Tables, and used immediately. Directions for where to find corrections will be found to the right on the pro forma.
d) Heavy solid borders denote intermediate calculation results which are NOT used immediately: they will either need to be copied into a box further down the page, or be needed as a 'lookup value' when consulting the Sight Reduction Tables.
e) Heavy speckled borders denote final results which we will use to plot the Line of Position, using the hints at bottom right of the form.
i) "Where do I find the 'Approximate True Bearing of the Sun' and what is the purpose of recording it".
This is an optional estimate (most easily made either by mentally dropping perpendicular from the sun to the horizon and using a hand bearing compass
for a rough bearing, or by using the vertical pin which some domed pedestal steering
compasses have, which will cast a shadow on or near the rim of the card.
If the sun is very high, neither method will be useable, particularly the first.
The idea is to compare this estimate with Zn, as a check on the sight reduction to make sure a big error has not been made in the calculations
ii) "What is Hc?".
Sorry: Tabulated Altitude. I've revised the pro-forma accordingly to show both.
iii) "Where are the yellow pages".
These are in the Nautical Almanac. Possibly they are not yellow in your Almanac, particularly if it's from an online source. I don't have a current
almanac to check, and if I did it would not be a US version, so YMMV
iv) What's with the funny
This is for the Almanac-derived 'd', to differentiate it from the Sight Reduction Tables 'd', which relates to a different part of the process.
v) What's with the "Same/Contrary" (hemisphere as declination)?
The idea is that you circle whichever of these words is true, so that when you go into the Sight Reduction tables, you have all the entry criteria at your mental fingertips.
This pro-forma is not designed to TEACH sight reduction, but to assist, with prompts and hints, someone who once knew how to do it.
Thanks for the queries ! - I'm grateful for the opportunity to make changes which improve the comprehensibility, not least because it may be that next time I get out a sextant
I've forgotten details of the procedure, or I'm not feeling that flash, and will need it to be as self explanatory as possible.
Anyone I've sent it to can request a fresh revision when this thread has died down (or if it doesn't pick up): I've already done a few minor changes, simply moving a few of the hints so it's clearer what they're attached to, and adding an explanatory label or two (such as "Tabulated Altitude".)
In the meantime, can I encourage anybody with further questions to post them on this thread rather than PM me, so that others can decide whether (and if so when) it's worth asking for a revision?