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» Online Classroom   » Celestial Navigation   » Public Discussion of Cel Nav   » Relationship between LHA and Z

Author Topic: Relationship between LHA and Z

 - posted December 17, 2020 11:18 AM      Profile for Jon           Edit/Delete Post 
I struggled with HBS Problem 24 Sight 35 (RFix 2560). I repeatedly went over my sight reduction (including redoing from scratch) and arrived at the same solution. It wasn't until after I "unblinded" my work by looking at the book wherein I was relieved to find DB's explanation. I, too, have arrived at a fix south of the 23rd Parallel. Then, I did Problem 25 (LAN) and *voila* I was north of it. While trying to unbug my solution (which ultimately was correct), I discovered that I do not understand the LHA and Z as I thought I had. Specifically, within Problem 24, the sun's LHA moves by the roughly 40 deg. which represent the ~2.75 hrs that have passed; however, Z only changes by approx. 12 deg. Why is that?
From: Parallel 47
David Burch

 - posted December 25, 2020 10:21 AM      Profile for David Burch           Edit/Delete Post 
I apologize. It seems this question was missed. Going forward, let us know if we are more than 48h late in responding.

This depends on the path of the body, which is relation between Lat and Dec. Bodies whose peak height is less than ~45º will change Zn at about 15º per hour. When the body will be much higher at noon, the rate can be much slower, then as it crosses near your zenith, it will be very much faster.

From: Starpath, Seattle, WA

All times are Pacific  
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