NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Interpolation to latitude
From: Gary LaPook
Date: 2009 Nov 9, 21:18 -0800
From: Gary LaPook
Date: 2009 Nov 9, 21:18 -0800
LMT is not zone time, it is the time at the local meridian so already includes the adjustment you are taking about. gl On Nov 9, 7:22�am,wrote: > L.Gray, "100 Problemsin Celestial Navigation" Problem 1-1 > > "...sailiing from New York to Azores... May 13, 1993. �DR position at 0730 (GMT) will be 40 deg 10' N and 50 deg 15' W. �Planning for a round of twilight sghts..." > > 50 deg 15 ' of long is equal to 3 hr. 21 m, which we add to LMT to get GMT. > > � � � � � � � � � � LMT � � �GMT > Nautical twilight �0337 � � �0658 > Civil twilight � � 0414 � � �0735 > Sunrise � � � � � �0446 � � �0807..." > > Appendix B (which is "how to") > > "1. On the right-hand daily page of the almanach, enter the upper half of the table (a.m) with the expeced DR latitude at the time of the twilight. (interpolate for latitude, either by eye or mathematically)...... Convert each LMT to GMT �by adding... or subtracting .. the time equivalent of the expected DR longitude-found on the first yellow page in the back of the almanach" > > My question is: why there is no mentioning �of interpolaion for the longitude in calculating twilight phenomenon? �As I mentioned before, I think the interpolation for the zone meridian ( in this case 45 deg W) should be included in calculation also. �I don't think it was included. � --~--~---------~--~----~------------~-------~--~----~ NavList message boards: www.fer3.com/arc Or post by email to: NavList@fer3.com To , email NavList+@fer3.com -~----------~----~----~----~------~----~------~--~---