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A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Need help to track down errors
From: Gary LaPook
Date: 2008 Nov 13, 05:14 -0800
From: Gary LaPook
Date: 2008 Nov 13, 05:14 -0800
I sent this email today to the government office that computed these tables: Dear Mr. Doherty, Last year I called your attention to some errors I had found in the on- line version of H.O. 249 for Hc's near zero and I checked recently and these appear now to have been corrected. However, when I was reviewing the updated version I found some additional errors. In volume 2 page 158 is completely wrong and appears to be a duplicate of page 152 and page 133 is also completely wrong and appears to be a duplicate of page 139! I suspect that there are many other similar errors hiding in this volume that my cursory review didn't reveal. Gary LaPook On Nov 13, 3:34 am, glap...@PACBELL.NET wrote: > Further comparison shows that page 133 is a duplicate of page 139! > > gl > > On Nov 13, 1:56 am, glap...@PACBELL.NET wrote: > > > Ken, > > > My copy, 1970 edition, doesn't have the error you pointed out. I then > > looked at all pages from 122 through 161 looking at the first entry on > > each of these pages and found additional differences between my print > > edition and the online version. Page 155 has a one minute different Hc > > as does page 151 for the first entry but I didn't check other values. > > page 133 is completely different, all tabulations are different ! I > > computed several of the entries on page 133 and found that the online > > version has the erroneous values while my 1970 edition has the correct > > values. > > > gl > > > On Nov 12, 4:08 pm, Ken Gebhartwrote: > > > > To all List Members, > > > > Need help to track down errors! > > > > I have been made aware of many errors on page 158 of Pub 249 Vol 2 > > > Apparently all of the Hc values on the page are wrong! For example, > > > for dec 0, LHA 0, Lat 26 (page 158), Hc is shown as 65 deg. When it > > > should be 64 deg by simple inspection. All the other numbers are > > > also off by varying amounts as can be found by computation. There > > > are some other errors too, of a different kind on other pages. For > > > example, page 160. Look at the column for dec 15 deg, and go down to > > > LHA 98. By simple inspection you can see that there should be a > > > minus sign before Hc 00-25, but it is not there. I believe this is > > > typical of many Hcs near zero. > > > > These errors are present in the US Government Edition, privately > > > published editions, and the PDF on the NGA website. I have spoken to > > > the UK Almanac Office, and they report that the errors do not exist > > > in their equivalent to 249 V2, or their Rapid Sight Reduction Tables, > > > and can find no trace or knowledge of them. > > > > I am asking anyone who has an older copy of this volume, to check it > > > for these errors and report the publication date. Maybe we can track > > > down when they first appeared. By the way, a friend did phone the > > > NGA to report this, and was told that �they would look into it�. > > > > Thanks, Ken Gebhart --~--~---------~--~----~------------~-------~--~----~ Navigation List archive: www.fer3.com/arc To post, email NavList@fer3.com To unsubscribe, email NavList-unsubscribe@fer3.com -~----------~----~----~----~------~----~------~--~---