Re: Moon chart question from new member

[heiner thiessen]

Dear Louise, Yes ,  EoT applies to all dial readings, whether by the Sun, the Moon or any stars or planets. EoT refers to the speed of the earth's rotation and so the sky with all its heavenly objects tells you about local apparent time. But your 48 minute rule is very much 'rule of thumb'. If you wanted a dial for your latitudes that uses the night sky it would be much better to use the principle of hour angles on the equatorial plane for the moon, or even better the difference in hour angles between Sun and Moon or between Sun and any stars of your choice. I designed a celestial ring dial which was featured in the BSS June 2003. It does not use the shadow of the Moon but its hour angle in the equatorial plane. Good luck. Heiner 51N/ 1W ----- Original Message ----- From: Louise Rigozzi To: [EMAIL PROTECTED] Sent: Monday, November 03, 2003 9:24 PM Subject: Moon chart question from new member Dear Sundial Mailing List members, I have just joined the list and have quite a tricky question to ask already!  I am working with Tony from Lindisfarne Sundials in England to create a sundial at a very high latitude (78 degrees) and I am including a correction graph for reading from the moon's shadow.  This is because for three to four months of the year there will be little or no sun.  I have made the graph illustrate the principle that the moon is 48 minutes 'fast' each day before the full moon and 48 minutes 'slow' each day after it.  The graph hopefully gives the idea that the more precise you can be with the number of days (and even half or quarter days) you are from the full moon, the more accurate your reading will be.  If anyone is interested in seeing it, I can JPEG it to you.  My main question is, after adding/subtracting the hours and minutes from the reading of the moon's shadow, whether you then need to add/subtract the minutes according to the Equation of Time (! which will also be shown on the dial face) for that day of the year.  Thanks!  Louise Rigozzi UK telephone number:  (01932) 843 417 Mobile:  07792 550052 Half price modem, FREE connection and one month FREE - click here to sign up to BT Broadband. -