A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Douglas Stephen
Date: 2015 Nov 5, 06:49 -0800
Hello all, I have a request for anyone who has the StarPilot celestial navigation program on the iPad, iPhone or iPod touch. I have used StarPilot for a good while and really like the program however there seems to be an error in the UT from Known Position part of the program that only occurs before noon. If you have the program would you please try the following and see if I am doing something wrong or there really is a small bug in the program? Am I missing something?
Lat = 40 degrees north, Long = 105 degrees west, default pressure and temperature for refraction and limb setting set to center.
I used the precompute to get an Hc and then entered that into UT from Known Position to calculate the time.
From the precompute routine for 08:00:00 I get Hc = 13 degrees 39 minutes and for 15:00:00 I get Hc = 18 degrees 07.2 minutes.
When I enter UT from Known Position with 08:00:00 and 13 degrees 39 minutes I get a delta watch time of 07:30:16 - a huge delta
When I enter UT from Known Position with 15:00:00 and 18 degrees 07.2 minutes I get a delta watch time of 00:00:19 - if I then ADD the refraction I would expect for 18 degrees 7.2 minutes (about 3 minutes) to the HC and enter 18 degrees 10.2 minutes I get a delta watch time of -00:00:01 which seems very reasonable.
I have not tried this with other hemispheres or night time values using stars since I first want to see if anyone else can replicate my problem.
Again, I really like StarPilot for all the other routines I have tired, I am just having trouble with UT from Known Position.