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Re: Sight reduction formulae
From: Stan K
Date: 2011 Dec 1, 14:43 -0500
From: Stan K
Date: 2011 Dec 1, 14:43 -0500
Randall,
In one version both lat and dec get signs, + for N, - for S.
In another version lat is always + and dec is - if lat and dec have different names (hemispheres), + if the names are the same.
Either way should give the same result.
You may have seen this on older vs. newer Power Squadrons sight reduction forms, the latter version being the newer.
Stan
In one version both lat and dec get signs, + for N, - for S.
In another version lat is always + and dec is - if lat and dec have different names (hemispheres), + if the names are the same.
Either way should give the same result.
You may have seen this on older vs. newer Power Squadrons sight reduction forms, the latter version being the newer.
Stan
-----Original Message-----
From: Randall.F.Morrow <Randall.F.Morrow@kp.org>
To: NavList <NavList@fer3.com>
Sent: Thu, Dec 1, 2011 2:37 pm
Subject: [NavList] Sight reduction formulae
I'm trying to do sight reductions by calculator but I'm having trouble with the sign(s). On example I have found is below but I have seen others in which the sign(s) do not change with same versus contrary latitude and declination. Is this correct? (I don't remember where I found this)
Thanks, Randy
Randall F Morrow PT
Kern County - Bakersfield
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From: Randall.F.Morrow <Randall.F.Morrow@kp.org>
To: NavList <NavList@fer3.com>
Sent: Thu, Dec 1, 2011 2:37 pm
Subject: [NavList] Sight reduction formulae
I'm trying to do sight reductions by calculator but I'm having trouble with the sign(s). On example I have found is below but I have seen others in which the sign(s) do not change with same versus contrary latitude and declination. Is this correct? (I don't remember where I found this)
Thanks, Randy
sin Hc = (cos LHA x cos DR lat x cos
dec) +
or - (sin DR lat x sin dec)
Note: use
+ if lat and dec are same names.
cos Az * = sin dec +/-
(sin Hc x sin DR lat) divided
by (cos Hc x cos DR lat)
Note: use
+ when lat and dec are of opposite names.
* Remember Az is the azimuth angle. To get
Zn (Azimuth) apply the rules:
Northern Lat: LHA > 180 deg. Azimuth
= Azimuth Angle. LHA < 180 deg. Zn = 360 - Az
Southern Lat. LHA > 180 deg. Zn =
180 deg. - Az. LHA< 180 deg. Zn = 180 + Az
Randall F Morrow PT
Kern County - Bakersfield
NOTICE TO RECIPIENT: If you are not the intended recipient of this e-mail, you are prohibited from sharing, copying, or otherwise using or disclosing its contents. If you have received this e-mail in error, please notify the sender immediately by reply e-mail and permanently delete this e-mail and any attachments without reading, forwarding or saving them. Thank you.