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Re: Z or ZN and a couple other fx 260 to excel conversions
From: Greg R_
Date: 2006 May 29, 13:57 -0700
From: Greg R_
Date: 2006 May 29, 13:57 -0700
Guy:
> 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?
Don't forget that when you reduce a sight by
tables (at least for HO 229 and 249, I can't speak for any of the other ones)
you're using a whole number for Latitude and LHA for your AP (which usually
isn't the same as your DR position).
Doing the reduction by calculator will give you an "exact" answer for whatever
you put in for your DR position. I haven't
tried it, but I think if you plot both LOPs you'll find that they'll land in the
same geographical position (i.e your Zn of 148 deg 11.4 is the azimuth of the
intercept from your AP for that sight, which is not necessarily also your
DR).
I'd also be glad to check your math with
Navigator Light and see what it says (theoretically should be the same results
as a calculator), but you didn't include a time for your sight, and it's kinda
hard to reduce something without one.. ;-)
> what is the equalvalent function in
excel to the Shift Sin-1
Aha - two minds on the same wavelength. I just
setup a little Excel spreadsheet the other day to do sight reductions - the
function you're looking for is ASIN, but don't forget that Excel works in
radians and you need to do that conversion first:
=SIN(A4*PI()/180)
where A4 = cell location for Lat value in this
case.
BTW, if you (or anyone else) has an easy way to
do trig calculations in Excel based on the DDMM.M format that we use with
sextant sights I'd love to hear about it. My current workaround requires
entering Degrees and Minutes.Decimals as two separate entries to do the math - a
bit unwieldy, but it seems to work.
--
GregR
(doing some celnav practice on this Memorial Day
holiday)
----- Original Message -----From: Guy SchwartzSent: Monday, May 29, 2006 11:56 AMSubject: Z or ZN and a couple other fx 260 to excel conversionsI was working out a problem here are the particluarsDR 40 deg 9 min N45 deg Wobject RegulusDec 11deg 59. 9 min NLHA 16:25:48HC 58 Deg 20.4 MinUsing 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 usingCos 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?New question, what is the equalvalent function in excel to the Shift Sin-1and the Shift Cos-1Thank you.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 0.959166009 0.717130586 Total A + B 0.851171807 Declination, +North -South Shift Sin-1(Hc) Latitude, +North -South 0999 Hc Cos-1 (Zn)= sin(dec) - sin(lat) x sin(Hc) / cos(Hc) x cos(lat) cos(Hc) x cos(lat) = A= 0.524877545 X 0.764359006 0.401194878 sin(lat) x sin(Hc) = B= 0.644790904 X 0.85117775 0.548831671 sin(dec) - B = C= 0.207883238 - 0.548831671 -0.340948434 C / A = D= -0.340948434 / 0.401194878 -0.849832469 Shift Cos-1 (Zn) 0999 Zn
