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## A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding

**Re: Z or ZN and a couple other fx 260 to excel conversions**

**From:**Guy Schwartz

**Date:**2006 May 30, 19:46 -0700

Bill: Thank you. Your answer is the missing piece to my puzzle I now added a test for sine of LHA >0 8-). Guy Hc and Zn by calculation using casio fx 260 calculator Sin-1Hc = sin(dec) x sin(lat) + cos(dec) x cos(lat) x cos(LHA) sin(dec) x sin(lat) = A= 0.207883238 X 0.644790904 0.134041221 cos(dec) x cos(lat) x cos(LHA) = B= 0.978153648 X 0.764359006 X 0.965389226 0.72178344 Total A + B 0.855824661 Declination, +North -South North Shift Sin-1(Hc) 58.85095947 Latitude, +North -South North 0999 Hc 58? 51.1' Cos-1 (Zn)= sin(dec) - sin(lat) x sin(Hc) / cos(Hc) x cos(lat) cos(Hc) x cos(lat) = A= 0.517255471 X 0.764359006 0.395368878 sin(lat) x sin(Hc) = B= 0.644790904 X 0.855831045 0.551832073 sin(dec) - B = C= 0.207883238 - 0.551832073 -0.343948836 C / A = D= -0.343948836 / 0.395368878 -0.869944134 Shift Cos-1 (Zn) 150.4521481 0999 Zn 209? 32.9' ----- Original Message ----- From: "Bill"To: Sent: Monday, May 29, 2006 4:00 PM Subject: Re: Z or ZN and a couple other fx 260 to excel conversions > Guy wrote > >> I was working out a problem here are the particluars >> DR 40 deg 9 min N >> 45 deg W >> object Regulus >> Dec 11deg 59. 9 min N >> LHA 16:25:48 >> HC 58 Deg 20.4 Min >> Using HO 249 the Z is 150 and the ZN is 210 I also checked with the star >> section and the ZN was the same. >> When I did the calculations using >> Cos rasied to -1 (Zn) = sin (dec) - Sin (lat) x sin (Hc) / cos (Hc) x cos >> (lat) >> >> The answer came out to 148 deg 11.4 min which is close to the 150 Z >> however I >> though that formula gave me the Zn? > > Yes and no, it is situational as the HC can be the same at some point > before > and some point after noon (using the sun as an example). With the sun LAN > (local area noon, sun at its highest point) is also the upper meridian > passage. For any body, LHA = 0 for upper meridian passage. To extract Zn > from Z, determine whether the body is rising (pre meridian passage) or > setting (post meridian passage. > > If rising, Zn = Z. If setting, Zn = 360 - Z. > > When in doubt, if the sine of LHA is positive, Zn = 360 - Z. When the > sine > of LHA is negative, Zn = Z. > > My memory device is "plus minus." When the sign of sine LHA is PLUS, Zn = > 360 MINUS Z. > > Bill > > > -- > No virus found in this incoming message. > Checked by AVG Free Edition. > Version: 7.1.394 / Virus Database: 268.7.4/351 - Release Date: 5/29/2006 > >