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Re: H.O. 218 Vs. H.O. 249
From: Stan K
Date: 2015 Nov 7, 17:35 -0500
From: Stan K
Date: 2015 Nov 7, 17:35 -0500
Ah ha! The difference is because the computed altitudes include the refraction correction (for a 5,000 foot flight altitude, but virtually the same as at sea level), according to Gary LaPook. Thanks, Gary. Nice having the archives.
Stan
-----Original Message-----
From: slk1000 <slk1000@aol.com>
To: navlist <navlist@fer3.com>
Cc: slk1000 <slk1000@aol.com>
Sent: Sat, Nov 7, 2015 5:10 pm
Subject: H.O. 218 vs. H.O. 249
From: slk1000 <slk1000@aol.com>
To: navlist <navlist@fer3.com>
Cc: slk1000 <slk1000@aol.com>
Sent: Sat, Nov 7, 2015 5:10 pm
Subject: H.O. 218 vs. H.O. 249
A short time ago I mentioned that I had a copy of Volume J of H.O. 218, but I had not done anything with it yet. Well, I started looking at it, and I am confused.
218 is similar to 249. I am working with Part 2 of 218, which corresponds to Volumes 2 and 3 of 249, the ones that do not refer to particular stars. I am finding what I consider significant differences between 218 and 249. For example:
Declination 1ºN
Latitude 40ºN
LHA 76º
For 249 and any method other than 218 I have tried, this gives an altitude of 11º20'. 218 gives 11º24'. The values of d and azimuth agree, it is just the altitude that is off. Most other sets of inputs I have tried disagree by one to four minutes of altitude, with an occasional one agreeing.
The volume I have is dated 1941. Is it possible that this edition has issues but later editions have different numbers? Or do all editions have issues? Or do I have issues?
Stan
