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: Rising angle of stars
    From: Steve E. Bryant
    Date: 2014 Oct 28, 17:31 -0500

    I checked with Stellarium to see that Mintaka's declination is 00-17'-21".  
    17'-21" is pretty close to east at the equator.  Of the three declinations 
    shown one was different from the other two.
    
    Sent from my iPhone
    
    > On Oct 28, 2014, at 5:08 PM, Steve E Bryant  wrote:
    > 
    > Would it be correct to assume that Mintaka's declination was zero?
    > 
    > Sent from my iPhone
    > 
    >> On Oct 27, 2014, at 1:47 PM, Frank Reed  wrote:
    >> 
    >> When you're at the equator, all stars rise vertically from the eastern 
    horizon. At other latitudes, stars due east (necessarily with declination 
    equal to zero) rise at an angle from the vertical equal to the latitude. 
    While driving east through dark, rural Rhode Island last night, I was 
    enjoying the view of Orion's belt rising in front of me. I could trace 
    Mintaka back at an angle from the vertical of 41° (near enough to my 
    latitude) and know that this was almost exactly due east as I drove along. 
    That got me wondering about the rising angle for other declinations or 
    azimuths... At home I decided to sit down and work it out. It turns out that 
    the relationship is simple. If theta, θ, is the angle with respect to the 
    vertical for a rising (or setting) star, then 
    >> tan θ = tan L / sin Z
    >> where L is latitude and Z is azimuth. For example, if the azimuth is 
    exactly either NE or SE as a star rises at latitude 45°, then the rising 
    angle is 54.7° away from the vertical. This is symmetrical north and south of 
    east, which surprised me a bit, though it makes sense in retrospect. 
    Naturally when Z=90°, the rising angle is equal to the latitude. At all 
    latitudes, for azimuths from 75° to 105° (within 15° of due east), the rising 
    angle is less than one degree greater than the latitude.
    >> -FER
    >> 
    >> 
    >> [PLAIN TEXT VERSION OF MESSAGE AUTO-GENERATED. ORIGINAL MAY INCLUDE MORE CONTENT]
    >> ----------------------------------------------------------------
    >> NavList message boards and member settings: www.fer3.com/NavList
    >> Members may optionally receive posts by email.
    >> To cancel email delivery, send a message to NoMail[at]fer3.com
    >> ----------------------------------------------------------------
    >> 
    >> 
    >> 
    >> View and reply to this message: 
    >> http://fer3.com/arc/m2.aspx/Rising-angle-stars-FrankReed-oct-2014-g29075
    >> 
    >> 
    >> 
    

       
    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