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    Re: Meridian transit adaptation
    From: David Pike
    Date: 2020 Nov 14, 03:46 -0800

    hi all, thanks frank, i have a problem with meridian transit. need to do a coast guard assessment for my capt license. they want me to do meridian transit other than the sun. i will need to rent a boat and dont want to drive a rented boat too far from shore or waste time. how can i figure out the bearing, time, etc ahead of time so i know the shot will be away from the lights of shore. or should i do this with polaris? does anyone want to get paid to  teach me that via phone or zoom or facetime or...whateverapp  thank u celestial community.
    u da best dave


    Welcome to NavList and also to the DavesList.  I think we can claim the majority with at least four of us now.  You need to find someone familiar with the USCG and their regulations.  I'm sure there'll be someone Navlist familiar with them.  Being from the UK, I know little except that they are perhaps a little anachronistic in their attitude to celestial. 

    Do you really have to do this at sea on a particular date and time of your choosing?  It seems to me you could wait a long time to get the correct combination of clear sky, visible horizon, and object other than the Sun in or close to meridian transit.  Bearing should be no problem.  You’ve got to be looking almost due north or south by definition. You might be lucky in daytime with the Moon or perhaps Venus if the Sun isn’t too high, otherwise you’re looking for suitable stars or planets during twilight.

    Using Polaris is a slightly different method of obtaining latitude.  I think the USCG would treat a Polaris observation as a separate exercise.  The trouble with many of these shortcuts is that by the time you’ve allowed for corrections; you might just as well have used a standard intercept method of sight reduction.

    Is it possible you must only hand in worked examples or need to prepare for a written examination?  That sounds a much more practical proposition.  In any case a tutor would need to know a few more details.  E.g. the exact license you want; the lat & long you’re operating in; if you’re using a marine sextant/natural horizon combination; and whether it’s a meridian passage or ex-meridian observation they want.  

    I hope you find someone, but in the meantime, you might like to look at  http://davidburchnavigation.blogspot.com/2015/11/latitude-by-meridian-transit-ex.html  .  Good luck. DaveP

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