Hello Fer (& others) I've given up on trying to make the Kitt Peak Sundial accurate to 1 sec because of Fer's comments concerning EOT corrections. It's impractical because it requires that I use hourly EOT values when laying out the time points and then, even still, it won't work right because the EOT changes from year to year. Too complicated for me and the users. (see Fer's comments below).
I think I will just correct our radio clock time for the this year's 12:00 solar noon value. DOES ANYBODY KNOW WHAT THIS VALUE IS? (I could find out myself, but I'm so busy that I need a little help from you guys right now cuz I'm really rushing to get things done.) So, I'm thinking I'll rewrite my proposal an give them a less ambitious estimate of the sundial's precision. In theory and practice do you think it is safe to forecast a precision of 15 seconds (by eyesight alone) or 5 seconds with a shadow sharpener? Will these more modest figures allow for errors caused by hourly and yearly EOT changes? Robert Hough, a new member of NASS, has graciously offered to help me lay out the time points. I'm thinking that we should go to the mountain the day before the summer solstice to lay out the three straight edges of the dial face perimeter with 3 taut strings (That's a total distance of 118m (388ft)!!!). On June 20th we will attempt some practice marks a and try to mark as many time points on that day as possible. This dry run will help us gain experience for the Big Day, the summer solstice. On the summer's solstice we'll be able to mark the entire daylight range of time possible from sunrise to sunset and will locate the sunrise and sunset marks as well. How does this sound? John John L. Carmichael Jr. Sundial Sculptures 925 E. Foothills Dr. Tucson Arizona 85718 USA Tel: 520-696-1709 Email: [EMAIL PROTECTED] Website: <http://www.sundialsculptures.com> ----- Original Message ----- From: "fer j. de vries" <[EMAIL PROTECTED]> To: "John Carmichael" <[EMAIL PROTECTED]> Sent: Sunday, May 19, 2002 4:06 AM Subject: Re: Proposal for Review > Hi John, > > I want to make a second remark to your proposal after reading it again, just > to conceder. > > At page 7 you write you want to lay out the dial on June 15 with EoT = 0. > You are 2 days late then......... > EoT = 0 already on June 13. > > Even then, the change of the EoT in 24 hours is about 12 seconds, that is > about 0.5 seconds in one hour. > Because you speak about a possible accuracy in the dial of 1 second in the > reading you should calculate the EoT for every moment or at least for every > hour and use it, even on June 13. > So in fact it doesn't matter what day you choose. > More important is to have the sun shining. > That would be a great problem in our country <G> > However, I was sitting in the sun outdoors when I read and reread your > proposal. > But several clouds pass also. > > Also have in mind that some programs to calculate the EoT give values for > local noon at Greenweich which should be translated to your location. > And what is the accuracy of the calculation program itself? > If the program has an accuracy less then 1 second the data may not be used. > > So I think this is a point to conceder. > Or just say that the accuracy of the reading is within half a minute but I > don't know if this is acceptable for you. > > In use the reading of the dial in one second for clock time only is possible > if each year a new table for the EoT is added and that table should give the > EoT for each hour for the specific location. > Some hours later the EoT is already changed a number of seconds. > > Best wishes, Fer. > > Fer J. de Vries > mailto:[EMAIL PROTECTED] > http://www.iae.nl/users/ferdv/ > Eindhoven, Netherlands > lat. 51:30 N long. 5:30 E > > ----- Original Message ----- > From: "John Carmichael" <[EMAIL PROTECTED]> > To: "fer j. de vries" <[EMAIL PROTECTED]> > Sent: Sunday, May 19, 2002 12:47 AM > Subject: Proposal for Review > > > > Hi Fer > > > > Here is my proposal. Could you look it over to see if you see anything > > wrong with it before I send it in? > > > > Thank you!!!! > > John > > > > John L. Carmichael Jr. > > Sundial Sculptures > > 925 E. Foothills Dr. > > Tucson Arizona 85718 > > USA > > > > Tel: 520-696-1709 > > Email: [EMAIL PROTECTED] > > Website: <http://www.sundialsculptures.com> > > ----- Original Message ----- > > From: "fer j. de vries" <[EMAIL PROTECTED]> > > To: "John Carmichael" <[EMAIL PROTECTED]> > > Sent: Saturday, May 18, 2002 8:52 AM > > Subject: Re: Multiple Wrap-around Styles > > > > > > > John, > > > > > > yes, please send me your proposel in PDF. > > > > > > Fer. > > > > > > Fer J. de Vries > > > mailto:[EMAIL PROTECTED] > > > http://www.iae.nl/users/ferdv/ > > > Eindhoven, Netherlands > > > lat. 51:30 N long. 5:30 E > > > > > > ----- Original Message ----- > > > From: "John Carmichael" <[EMAIL PROTECTED]> > > > To: "Sundial List" <[email protected]> > > > Cc: "Robert Wilson" <[EMAIL PROTECTED]> > > > Sent: Friday, May 17, 2002 7:31 PM > > > Subject: Multiple Wrap-around Styles > > > > > > > > > > Hello All > > > > > > > > I've made measurements, drawings and a working model of my proposed > > > sundial > > > > adaptation of the McMath-Pierce Solar Telescope at Kitt Peak, Arizona > > and > > > am > > > > submitting a proposal to Kitt Peak officials soon. I'll also be > giving > > a > > > > short talk on this giant sundial at the NASS conference. > > > > > > > > Early on in the dial face design, I realized that this very thick > gnomon > > > has > > > > four possible styles because it is in the shape of a square box, each > > > corner > > > > being a different style that functions at different times of the day. > I > > > > noticed that as the sun moves around the gnomon, the leading edge of > the > > > > shadow is produced by different styles and that there is an > > instantaneous > > > > moment of transition when the style shifts to the next style. The > only > > > > thing an astute observer sees on the ground at this moment is that the > > > "fuzz > > > > zone" of the shadow will change a little in width, otherwise the > > shadow's > > > > movement is a smooth, continuous motion. This is great, because it > means > > > > that on the face, the hour numbers will appear in consecutive > numerical > > > > order just like on an ordinary sundial. (The spacing between the hour > > > points > > > > gets a little strange during the style shift, however). It will be > very > > > > user-friendly. > > > > > > > > But its design is more difficult. I found that none of these styles > > work > > > > all day, because they are all shaded at sometime during the day by the > > > > structure. So to make a sundial with hour points from sunrise to > > sunset, > > > I > > > > have to use multiple styles. It takes at least three styles to cover > > the > > > > entire span of daylight hours. (I use the bottom, east and top styles > > in > > > my > > > > design). > > > > > > > > Has anybody ever heard of a one-faced sundial with multple wrap-around > > > > styles? For example, instead of a four-sided gnomon, how about a three > > or > > > > fived-sided gnomon (You can exclude the common two-sided thick gnomon > > and > > > > the analemma shaped gnomon). > > > > > > > > p.s. If anybody would like me to send a PDF of my drawing, let me > > know... > > > > > > > > John > > > > > > > > John L. Carmichael Jr. > > > > Sundial Sculptures > > > > 925 E. Foothills Dr. > > > > Tucson Arizona 85718 > > > > USA > > > > > > > > Tel: 520-696-1709 > > > > Email: [EMAIL PROTECTED] > > > > Website: <http://www.sundialsculptures.com> > > > > > > > > - > > > > > > > > > > > > > > -
