(07-09-2018, 11:26 PM)CarlosPindle Wrote: (06-13-2017, 10:29 AM)Rdutton Wrote: Ed & Rumata,
Table 5 in Pub. No. 249 gave me the same results you're describing.
Thanks to Rumata, Pub. No. 229 gives the basic formula as seen below. After running a few examples through the calculator the correct results were obtained every time using the formula.
So far....so good.
Thanks for the ideas men.
Roland
Now I'm really confused! What "altitude difference"? Is that the altitude difference between the uncorrected Hc found in Pub No. 249 (or 229) and Ho?
Thanks fellas,
Carlos
Example
total Dec = 16:07.4
From pub 249: Dec 16, AP lat 10, LHA 19
HC d Z
70:33.0 -17 70
Correction (7.4/60) X -17 = -2.1 minutes; or use table 5 (d=-17. min=7.4)
So HC 70:33.0 - 00:02.1 = 70:30.9
corrected HC 70:30.9
- HO 70:29.1
= 1.8 NM away from body as measured from AP
Tell me if I got something wrong
joe
Ok... this really is small beans, but I feel compelled to point something out about table 5 that I did not notice before.
The top horizontal row that goes from 1 to 60 makes sense because pub 249 'd' range is the same (d=00 just means no correction).
The side vertical column goes from 0 to 59 which makes sense because minutes of lat or long or elevation or dec increments range the same (one does not use 60 because that means 1 degree.
So whether or not a typical correction seems to work despite which row or column is chosen, if you have a 'd' of 60, or 0 minutes, it will make a difference.
So what I think I found out is that the top row labeled d is in fact the 'd' factor range, and the side column is the declination minutes otherwise unaccounted for when entering 229 and 249. The whole HC correction thing (d factor) is probably based not only on left over minutes of declination, but also the difference between dec lat and AP lat... or perhaps Z. Not being a spherical trig professor, Im just guessing at this point. Just imagine that if every decimal LHA, DEC, and AP lat were accounted for in 229 or 249 the book would be larger than the library of congress.
joe