Welcome to the NavList Message Boards.

NavList:

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

Compose Your Message

Message:αβγ
Message:abc
Add Images & Files
    or...
       
    Reply
    Re: Sight reduction formulae
    From: Stan K
    Date: 2011 Dec 1, 14:51 -0500
    Randall,

    In my previous e-mail I should have added that
    1) in the sin formula, that sign is always +
    2) in the cos formula, that sign is always -, but the formula is missing parentheses
    cos Az * =  (sin dec +/- (sin Hc x sin DR lat)) divided by (cos Hc x cos DR lat)

    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

    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.
       
    Reply
    Browse Files

    Drop Files

    NavList

    What is NavList?

    Join NavList

    Name:
    (please, no nicknames or handles)
    Email:
    Do you want to receive all group messages by email?
    Yes No

    You can also join by posting. Your first on-topic post automatically makes you a member.

    Posting Code

    Enter the email address associated with your NavList messages. Your posting code will be emailed to you immediately.
    Email:

    Email Settings

    Posting Code:

    Custom Index

    Subject:
    Author:
    Start date: (yyyymm dd)
    End date: (yyyymm dd)

    Visit this site
    Visit this site
    Visit this site
    Visit this site
    Visit this site
    Visit this site