NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Additional error found in H.O. 249
From: Brad Morris
Date: 2009 Oct 7, 16:25 -0400
From: Brad Morris
Date: 2009 Oct 7, 16:25 -0400
Hi Gary What is the magnitude of these errors? Several arc-seconds? An arc-minute? Several arc-minutes? A degree?!!?!?!? My 1853 Bowditch gives a long term almanac, in which the motion or rate for the stars is given for a year, and you just multiply by years and add to the base value. Surprise, it agrees quite readily with current values (not perfectly, but dang close). It didn't seem like a huge delta for a 156 year run (1853 -> 2009). I can't imagine this to be a huge injected error for 1982 -> 2009. I do understand that stars have proper motion. Wouldn't one obtain the SHA and declination of a star from the Nautical Almanac for the day in question? Why would it be preferable to obtain this from HO 249 other than convenience? Best Regards Brad -----Original Message----- From: navlist@fer3.com [mailto:navlist@fer3.com] On Behalf Of Gary LaPook Sent: Wednesday, October 07, 2009 3:59 PM To: navlist@fer3.com Subject: [NavList 10095] Re: Additional error found in H.O. 249 Here is the response I received today: Gary While the Navigational Stars pages may be somewhat out-of-date, this is not really considered an error. Our policy is that on-line publications should contain the same information as their current printed editions. The 1982 editions of Volumes 2 and 3 are still the current issues of these publications. The Navigational Star pages will be updated when the next editions are issued. Regards, Tim Doherty Office of Global Navigation/Technology National Geospatial-Intelligence Agency gl glapook@pacbell.net wrote: > Tim Doherty > Office of Global Navigation/Technology > National Geospatial-Intelligence Agency > > > I hate to point an error that still remains in H.O. 249. This one is > fairly minor. Each of the on line volumes contain a table of the > positions of the navigational stars. Volume 1 has the table for the > current positions of the stars, epoch 2010. However, volumes 2 and 3 > have the table with the positions of the stars in 1985 which is > unusable this many years later. You should replace those tables with > the correct one from volume 1. > > Gary LaPook > > > > > "Confidentiality and Privilege Notice The information transmitted by this electronic mail (and any attachments) is being sent by or on behalf of Tactronics; it is intended for the exclusive use of the addressee named above and may constitute information that is privileged or confidential or otherwise legally exempt from disclosure. If you are not the addressee or an employee or agent responsible for delivering this message to same, you are not authorized to retain, read, copy or disseminate this electronic mail (or any attachments) or any part thereof. If you have received this electronic mail (and any attachments) in error, please call us immediately and send written confirmation that same has been deleted from your system. Thank you." --~--~---------~--~----~------------~-------~--~----~ NavList message boards: www.fer3.com/arc Or post by email to: NavList@fer3.com To , email NavList+@fer3.com -~----------~----~----~----~------~----~------~--~---