Welcome to the NavList Message Boards.


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

Compose Your Message

Add Images & Files
    Re: Examples of cocked hat far from equilateral
    From: David Pike
    Date: 2019 Feb 14, 11:54 -0800

    Bill some non equilateral sextant sights for you.  I observed them today on the Sun after doing ten calibration sights on each stud setting using Franks GPS Antspoof App and finding an average instrument error.  I've purposely not put my observation position on, but it's not far from 53N 000.30W.  I rather like using the basic Hughes MkIX.  It's much lighter and much better balanced than the clockwork ones.  This one was overhauled by Paul Brewer and it works a treat.  We don't try to fiddle too much with the calibration.  We just accept what we get.  It's in one of the original aluminium cases, before they stole all the alminium to build Spitfires.  I used 'Navigator' to find GHA and Dec Sun being too lazy to do all that time to arc stuff.  We didn't need that on Vulcan's; with five people helping, we always managed to centre about an Air Almanac ten minute time.  I'm taking a bit of a risk sending this without tripple checking it, but it's a clear night, and I thought I'd go out and find somewhere with no light polution and get some star sights before the mist comes in. 

    Sextant:  H. Hughes & Son Bubble Sextant MkIX Serial No 230/40

    Calibration:  10d stop add 6’,  10d +5d stop add 6.5’, 20d stop add 6.9’

    Date: 14th February 2019 DR Position 53d00’N 000d.30’W Assumed Latitude 53dN

    Body: Sun, Centre, Bubble Horizon

    Time: 10.03.07             GMT Hs 17d 50.6’

                                      Inst corn          +6.0’

                            Refraction                   -3.0’

                            Ho                       17d 53.6’


    GHA Sun                     327.14.1    From ‘Navigator’

    Assumed Longitude     000.14.1W

    LHA Sun                      327                  Dec 13d02.8S From ‘Navigator’

    Az:                               146                  Hc:  18d11’ d-56         From AP3270 Vol 3

                                                    d Corr’n             -2’


    Intercept:                      15.4’Away

    Time: 13.05.55 GMT Hs 22d 53.8’

                            Inst corn          +6.9’

                            Refraction        -2.0’

                            Ho            22d 58.7’

     GHA Sun                     012.56.1    From ‘Navigator’

    Assumed Longitude      000.56.1W

    LHA Sun                      012                  Dec 13d00.3S From ‘Navigator’

    Az:                               193                  Hc:  23d12’ d-59         From AP3270 Vol 3

                                                    d Corr’n             -0’


    Intercept:                      13.3’Away

    Time: 16.04.51 GMT Hs 07d52.6 ’

                            Inst corn          +6.5’

                            Refraction          -7.0’

                            Ho            17d 52.1’

     GHA Sun                     057.40.2    From ‘Navigator’

    Assumed Longitude      000.40.2W

    LHA Sun                      057                  Dec 12d57.7’   From ‘Navigator’

    Az:                               236                  Hc:  08d54’ d-52         From AP3270 Vol 3

                                                    d Corr’n           -50’


    Intercept:                      11.9’Away



    Browse Files

    Drop Files


    What is NavList?

    Join NavList

    (please, no nicknames or handles)
    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 Settings

    Posting Code:

    Custom Index

    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