Doesn't matter which row or column in Table 5?

[EdCa]

Here's and odd question- does it matter whether you use the column for minutes of declination or "d" correction from Pub. No. 249 to get the proper "d" correction?  By this I mean I've discovered that whether 249 specifies any "d" correction (45 for example) and the Sun's declination for a certain day and time (let's just say 21 minutes of declination) the same correction value of 16 can be found whether you use 45 minutes of declination and a "d" of 21 or 21 minutes of declination and a "d" value of 45.  No matter which way you  arrange it you still get a d correction of 16.

That would let me think that Table 5 is goof proof- you'll still get the same d correction value.

What do you think?

Thanks,

Ed


TABLE 5- Correction to Tabulated Altitude for Minutes of Declination

[Rumata]

Here's and odd question- does it matter whether you use the column for minutes of declination or "d" correction from Pub. No. 249 to get the proper "d" correction?  By this I mean I've discovered that whether 249 specifies any "d" correction (45 for example) and the Sun's declination for a certain day and time (let's just say 21 minutes of declination) the same correction value of 16 can be found whether you use 45 minutes of declination and a "d" of 21 or 21 minutes of declination and a "d" value of 45.  No matter which way you  arrange it you still get a d correction of 16.

That would let me think that Table 5 is goof proof- you'll still get the same d correction value.

What do you think?

Thanks,

Ed


TABLE 5- Correction to Tabulated Altitude for Minutes of Declination

---

Here's and odd question- does it matter whether you use the column for minutes of declination or "d" correction from Pub. No. 249 to get the proper "d" correction?  By this I mean I've discovered that whether 249 specifies any "d" correction (45 for example) and the Sun's declination for a certain day and time (let's just say 21 minutes of declination) the same correction value of 16 can be found whether you use 45 minutes of declination and a "d" of 21 or 21 minutes of declination and a "d" value of 45.  No matter which way you  arrange it you still get a d correction of 16.

That would let me think that Table 5 is goof proof- you'll still get the same d correction value.

What do you think?

Thanks,

Ed


TABLE 5- Correction to Tabulated Altitude for Minutes of Declination

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Greetings EdCa, I think some explanation may come from Pub.229, Vol.1, Page XI, 4. Interpolation Table. (a) Design.

Hope it can help.

[Rdutton]

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

[pabrides]

Tell me if Im wrong: The 'd' underlined with a minutes symbol in the upper corners would indicate the top row of numbers are the 'd' correction factors listed in 229 or 249; the minutes symbol would indicate the vertical numbers are minutes of declination past the hour. However it appears that it makes little difference which column or row is used for 'd'f or dec inc. It all boils down to (dec inc/60) X 'd'f... Is my understanding correct???

joe

[Fred_B]

Joe,

"the minutes symbol would indicate the vertical numbers are minutes of declination past the hour."

The ' (minutes symbol) is only the minutes of declination for, let's say, the Sun (or any celestial object).

Here's an example;

Date- July 9, 2018
Time- 12:00:00 GMT
Body- Sun
Declination- 22° 19.4

Lets' say when doing a Sun sight reduction you find a "d" value of 22 in Pub. 249 or 229.

Using the minutes of declination 0° 19' (rounded down as the .4 isn't important) and the "d" of 22 a "d correction" figure of 7 is found.

That being said, it doesn't matter which column you use to obtain the d correction- the result is the same.
I've never been able to figure out how to mathematically get d.

Does that help?

Fred

[pabrides]

Joe,
 
That being said, it doesn't matter which column you use to obtain the d correction- the result is the same.
I've never been able to figure out how to mathematically get d.

Does that help?

Fred

Thanks Fred... :) 

I think d in 229/249 is the actual change in declination from hour to hour.  Im probably wrong

joe

[CarlosPindle]

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

[pabrides]

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