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    Re: Additional altitude correction for Venus
    From: Stan K
    Date: 2015 May 15, 10:43 -0400
    Catherine Hohenkerk came through again.  The change occurred in 1985.  The relevant part of her response is below.


    -----Original Message-----
    From: Hohenkerk Catherine <Catherine.Hohenkerk@UKHO.gov.uk>
    To: 'slk1000@aol.com' <slk1000@aol.com>
    Cc: hmnao <hmnao@UKHO.gov.uk>
    Sent: Fri, May 15, 2015 8:33 am
    Subject: RE: [NavList] Re: Additional altitude correction for Venus - RESOLVED

    Dear Stan,
    Thank you for your e-mails.  I was preparing an answer, but you have half answered it! 
    I do agree that in older NAs its not very clear!  This is what I wrote yesterday …
    In the 1980's it was decided that in The Nautical Almanac (NA), for Venus, the
    tabulated values of GHA and Dec should be changed from the centre of the disc
    to the centre of light (i.e. to take account of the phase), since this is what
    the observers would be measuring their altitudes from.  The effect of the change
    changed the additional corrections tabulated on page A2 and the wording in the
    explanation (usually near the bottom of page 259).
    This change was implemented in 1985.  Looking on page 259 of
    the NA for 1985, it states in the penultimate paragraph:
    "Since 1985, the phase correction for Venus has been incorporated in the
    tabulations for the G.H.A. and Dec., and no correction for phase is required."
    HM Nautical Almanac Office
    United Kingdom Hydrographic Office
    Admiralty Way
    Taunton TA1 2DN

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