Re: martian analemma & EOT
Hello John, You're pretty unbelievable too ;) Here (I hope) are some answers to some of your questions. 1) The obliquity effect is responsible for the figure-eight shape. It's shaped this way because the obliquity value in the course of one year has four zeros, i.e., two maximums and two minimums. The eccentricity effect results in an elliptical shape, it does not "cross-over" on itself (form a figure-eight) because it has only two zeros, i.e., one maximum and one minimum. The following URL illustrates the graphs of the two components over the course of a year and how they combine to result in the EoT. Remember that the EoT is the summed difference of the apparent solar day length and mean solar day length. You can see this directly be tracking the solar day length at various dates in Graph A and see how they effect "the total" below in Graph B. For example, when the day length value in Graph A goes through zero the EoT value in Graph B is at a maximum, this makes sense, yes? ftp://ftp.gcstudio.com/pub/sundial/sday_eot.gif The following URL illustrates the shape of each of the two components as well as the final result when the two are combined, i.e., the Analemma itself. ftp://ftp.gcstudio.com/pub/sundial/analemma.gif 2) The magnitudes of each of these two effects AND the phase in which they are related to one another determines the final shape. It's possible where one effect alone can dominate. In the case of Mercury, eccentricity alone determines the shape. For example, in the solar day and EoT graph (first URL above) visualize what would occur if you were to slide the eccentricity values around the fixed obliquity values, this would change how they combine, right? Something similar is actually occurring, i.e., the longitude of perihelion and the vernal equinox are moving relative to one another at almost an arc-min per year! Also, the magnitudes of obliquity and eccentricity change in time as well but on a much slower scale. In summary: 1) Obliquity (if it exists) causes the figure-eight 2) Eccentricity (if it exists - and Kepler seemed to think so) distorts the shape of the figure eight. 3) The distortion is created when the two are combined. This in turn depends on each of their relative magnitudes and how they are related to one another, i.e., their phase to one another. 4) Remember that in the physical sense these two effect are modulating the apparent right ascension of the Sun, i.e., the EoT = RA(apparent) - RA(mean). THIS IS SUPER IMPORTANT!!! 5) Consider how the values operate on a daily basis and then realize that it is their summation that lead to the EoT. Finally, Mars has a high eccentricity value, third highest in the solar system (Earth has the third lowest) and a moderate obliquity value (very close to our own). Eccentricity is dominate, i.e., no figure-eight. -Luke John Carmichael wrote: > > You guys are unbelieveable! I've had the martian analemma & EOT question > for a long time but never asked it for fear that you'd think I was a bit > crazy. I thought who would even go to the trouble to calculate it since > there's not a big market for sundials on Mars. I'm delighted that someone > else has had the same question and even has a picture of one! > > Understanding why analemma and EOT curves take the shape that they do is a > question that we have all struggled with. In fact, is is in the top ten of > the FAQs that I recieved. I've always thought that if you compare the > factors which determine the curve for two different planets, then it would > be a lot easier to see how each factor affects the curve's shape. > > Now I know the shape of the EOT curve is determined by the earth's axis > inclination and the eccentricity of its orbit. Which of these two factors > cause the two big humps and the two small humps of the curve? > > The analemma's shape is simply the EOT values plotted against the solar > declination. Right? Which of these factors causes the figure eight? Why is > one lobe bigger than the other? Why is the analemma slightly off center > vertically? Why doesn't Mars also have a figure eight analemma? > > I'm sure there are many people who'd like answers to these questions myself > included. I have my own theories but I'm not sure that they are correct. > > Thanks for dealing with my flood of questions this week. > > John Carmichael > Tucson Arizona > > is>Hello, > > > > The March '82 Sky&Tel article, "The Analemmas of the Planets", is an > >interesting piece, I scanned a portion of my copy and posted the image > >of the Martian Analemma at the following URL. > > > >ftp://ftp.gcstudio.com/pub/sundial/marseot.jpg > > > > As Robert mentions it has a teardrop shape, this I believe is due to > >the fact that the eccentricity component currently dominates over the > >figure-eight shape of the planet's obliquity component. If I'm not > >mistaken, I believe Earth's Analemma had such a shape (teardrop) some > >95,00
Archaelogical site in Abruzzo Italy
Hello, I will try to traslate the message I sent to the italian mail list Gnomonicaitalia, according to Fer De Vries request. In the last number of the National Geographic (Italian Version), there is an interesting article about an archaeological site in Fossa (AQ) in Abruzzo, Italy, where a pre-roman necropolis( sec. X - I BC) has been found. The site is covered by graves that shows an orientation EST-WEST. In the italian version of this mail you can find a photo showing some graves with stones alignaments. The article says that those stones (max 2,5 mt high) are placed in a decreasing order on the floor starting from the grave's circle. The explanation of this configuration isn't sure. Archaeologists thinks that the meaning of those alignaments is astronomical, but at the moment no one can imagine its real meaning. A computer project is studing the position of the sun on the lasts 3000 years and the shadows projected by the stones according to the seasons and the hours of the days. If the stone's astronomical function will be proved, at last we will have an original and ancient group of sundial's instruments. Ciao Marco Rossi Caorle -VE-
Re: Dollars and Sense!
On Sat 4 Dec 1999 (11:31:46 +), [EMAIL PROTECTED] wrote: > My preferred solution is for a bank draft in 'Pounds Sterling' and I > remember being told that there are agencies who can handle this by post > at reasonable rates. If anyone can recommend a US agency to handle > such things, or a better method, I'd be pleased to pass on the good > news. Yes, Tony, I know what you mean - I used to have the same problem with USA payments (perhaps more so than yorself!), as my amount 'per sale' is less. For USA customers without a Bank Account, the best method is probably by a "MoneyGram" - which can be used to send a payment from most USA to UK Post Offices, and has a relatively small fee to your customers of about $12 US. A much better method is to have your customer 'wire' the money straight in to any UK Bank Account, using the International Electronic Banking System. If the amount is in UK Sterling, then you will receive the full value (ie, without any loss in Dollar-to-Pound conversion) - and even if this payment is received in US Dollars (or whatever currency), the Bank will not deduct any 'commission', as it would for handling a cheque in a foreign currency. At least, this is the situation with my own "Royal Bank of Scotland" - but there are 'variations' between UK Banks (just as for any commission fees). Because these transactions are treated as 'automated credits', and reduces the Bank's workload on 'manual' processing, any bank charges (per payment) will probably be less than paying-in a normal UK cheque - and for the same reason, the customer's Bank would normally charge them less than getting a 'Bank Draft', or (in some cases) may not charge customers anything at all, although this seems to vary from Bank to Bank particularly within the USA. As an incentive we offer our customers a 5% discount for 'wired' payments, as well as a further 10% discount for giving their Latitude and Longitude. Incidentally, I wonder how many "American-made" dials are sold in the UK ? Regards, Douglas Hunt. -- "MODERN SUNCLOCKS" - 'Human Sundials', using YOUR OWN SHADOW to tell time. Looking for a useful self-funding Millennium-marker ? - you've found one ! For details, see Web-site at http://www.argonet.co.uk/education/sunclocks/ Mail Address: 1 Love Street, Kilwinning, Ayrshire, Scotland, KA13 7LQ, UK. Tel & Fax (UK): 01294-552250. International Tel & Fax: + 44 1294 552250. E-mails to: "[EMAIL PROTECTED]" or "[EMAIL PROTECTED]"
Re: Dollars and sense!
I believe there is no commission charge to the recipient of a Pound Sterling Money Order. The charge to the purchaser is typically a few dollars but depends on one's bank plan or whether one purchases a money order at the post office. Bank drafts typically cost the purchaser a dollar or two more than a money order. -- Richard Langley Professor of Geodesy and Precision Navigation On Sat, 4 Dec 1999, Tony Moss wrote: >Fellow Shadow Watchers, > Just at the moment a fair amount of my brassware >seems to be heading for the USA and this always presents the problem of >payment in another currency and the disproportionate amount of commission >charged by the *licenced robbers* - sorry - 'banks' when handling small >amounts. > >My preferred solution is for a bank draft in 'Pounds Sterling' and I >remember being told that there are agencies who can handle this by post >at reasonable rates. If anyone can recommend a US agency to handle such >things, or a better method, I'd be pleased to pass on the good news. > >Best Wishes > >Tony Moss > >P.S. I've looked at credit card trading but this doesn't work for >smallish irregular transactions. It would be ideal otherwise. > > === Richard B. LangleyE-mail: [EMAIL PROTECTED] Geodetic Research Laboratory Web: http://www.unb.ca/GGE/ Dept. of Geodesy and Geomatics EngineeringPhone:+1 506 453-5142 University of New Brunswick Fax: +1 506 453-4943 Fredericton, N.B., Canada E3B 5A3 Fredericton? Where's that? See: http://www.city.fredericton.nb.ca/ ===
Dollars and sense!
Fellow Shadow Watchers, Just at the moment a fair amount of my brassware seems to be heading for the USA and this always presents the problem of payment in another currency and the disproportionate amount of commission charged by the *licenced robbers* - sorry - 'banks' when handling small amounts. My preferred solution is for a bank draft in 'Pounds Sterling' and I remember being told that there are agencies who can handle this by post at reasonable rates. If anyone can recommend a US agency to handle such things, or a better method, I'd be pleased to pass on the good news. Best Wishes Tony Moss P.S. I've looked at credit card trading but this doesn't work for smallish irregular transactions. It would be ideal otherwise.
Re: martian analemma & EOT
John Carmichael contributed: > >You guys are unbelieveable! I've had the martian analemma & EOT question >for a long time but never asked it for fear that you'd think I was a bit >crazy. I thought who would even go to the trouble to calculate it since >there's not a big market for sundials on Mars. Not so fast John! Just this week the Chamber of Trade in my hometown (Bedlington, Northumberland, England) have arranged with NASA to send a CD ROM with the names and details of the inhabitants and town maps etc. to Mars in 2001. In addition they have put forward a claim for an area the size and shape of Bedlington on the Red Planet for colonisation. Naturally Lindisfarne Sundials will have a branch office there although advance orders for Martian dials may be held up until supplies of *brass* can replace the crates of ladies' lingerie items incorrectly scheduled for the first delivery of raw materials. :-) "%+0> *£!`±§" (Best Wishes in Martian) Tony Moss == \ ** ** \\ ** ** \\** *** *\\ ** ** *\\ ****** **\\ ***\\ Tony Moss, Lindisfarne Sundials *\\ 43, Windsor Gardens, Bedlington, ***\\Northumberland, England, NE22 5SY, **\\55° 07' 45" N1° 35' 38" W Tel/FAX +1670 823232 Mobile: 07970 208 540 Website: http://www.lindisun.demon.co.uk == The first choice for a Millennium Sundial. (every one Y2K compliant) Horizontal, Vertical, Declining, Analemmatic, Equatorial, Polar and Capuchin Sundials individually made in solid engraving brass. Professional-quality Dialling Scales, 'engine-divided' meridian layout instruments with software. Analemmatic dial plots - any size for any latitude. Graduation, re-cutting and restoration of scales. 'Lintique' patination of brass. ===
graphic conversion
I wonder if anyone in this group knows of software that converts a Word file to a gif or jpeg or a postscript file to a gif or jpeg or a PDF file to a gif or jpeg. Thanks for any help. Dan Wenger Daniel Lee Wenger Santa Cruz, CA [EMAIL PROTECTED] http://wengersundial.com http://wengersundial.com/wengerfamily
Re: graphic conversion
On Sat, 4 Dec 1999, Daniel Lee Wenger wrote: > I wonder if anyone in this group knows of software that converts a > Word file to a gif or jpeg > or a > postscript file to a gif or jpeg > > or a > > PDF file to a gif or jpeg. > > Thanks for any help. > Dan Wenger > > Daniel Lee Wenger > Santa Cruz, CA > [EMAIL PROTECTED] > http://wengersundial.com > http://wengersundial.com/wengerfamily Dan: This is *not* a high-tech solution, but it works... I do a screen capture (simply hit the 'print' key) with the desired word page, or pdf screen displayed. Bring up START>>ACCESSORIES>>PAINT, click in the blank page that paint opens for you, and paste the clipboard in. (Either right-click and select Paste, or EDIT>>PASTE from the menu bar.) Paint will very likely ask if you want to expand the default page size to fit the stuff you are pasting; OK that. Scroll about a bit, to center up the image you want to save. Select Tool from the toolbox, and click-drag to select the are you want to make into your gif or jpg. (This lets you get rid of the borders of the screen, task bar, other desktop "noise".) When the dotted outline encloses the area you want, right-click and Copy it. Select FILE>>NEW from the menu, and abandon the changes you've made (pasting in the clipboard). Right-click and Paste into the new blank screen, again expanding as necessary to fit the image. Finally, from the menu, select FILE>>SAVE AS and choose gif or jpg file type, rather than the default bmp. You also asked about converting ps files. Just today, I ran into a great conversion program pointed to from John Hoy's sundials page (John's is: http://axum.tripod.com/). This is a Java front-end that lets you upload your ps file, and gives you back a pdf! Open with Acrobat Reader, and save as above... Find it at: http://www.ps2pdf.com/cgi-bin/ps2pdf Dave
Re: martian analemma & EOT
You guys are unbelieveable! I've had the martian analemma & EOT question for a long time but never asked it for fear that you'd think I was a bit crazy. I thought who would even go to the trouble to calculate it since there's not a big market for sundials on Mars. I'm delighted that someone else has had the same question and even has a picture of one! Understanding why analemma and EOT curves take the shape that they do is a question that we have all struggled with. In fact, is is in the top ten of the FAQs that I recieved. I've always thought that if you compare the factors which determine the curve for two different planets, then it would be a lot easier to see how each factor affects the curve's shape. Now I know the shape of the EOT curve is determined by the earth's axis inclination and the eccentricity of its orbit. Which of these two factors cause the two big humps and the two small humps of the curve? The analemma's shape is simply the EOT values plotted against the solar declination. Right? Which of these factors causes the figure eight? Why is one lobe bigger than the other? Why is the analemma slightly off center vertically? Why doesn't Mars also have a figure eight analemma? I'm sure there are many people who'd like answers to these questions myself included. I have my own theories but I'm not sure that they are correct. Thanks for dealing with my flood of questions this week. John Carmichael Tucson Arizona is>Hello, > > The March '82 Sky&Tel article, "The Analemmas of the Planets", is an >interesting piece, I scanned a portion of my copy and posted the image >of the Martian Analemma at the following URL. > >ftp://ftp.gcstudio.com/pub/sundial/marseot.jpg > > As Robert mentions it has a teardrop shape, this I believe is due to >the fact that the eccentricity component currently dominates over the >figure-eight shape of the planet's obliquity component. If I'm not >mistaken, I believe Earth's Analemma had such a shape (teardrop) some >95,000 years ago. > > BTW, the article also illustrates a "human" Analemmatic Dial with an >Analemma implemented for EoT correction, the dial is in Tucson Arizona >at the Flandrau Planetarium. > >Best, > >Luke > > >R.H. van Gent wrote: >> >> John Carmichael wrote: >> >> > I usually don't write two different letters to the list on the same day, but >> > could'nt resist the following question in view of today's landing on Mars. >> > >> > What would the martian analemma and Equation of Time look like? >> >> Martian and other non-terrestrial analemmas were discussed in: >> >> David A. Harvey, "The Analemmas of the Planets", Sky & >> Telescope, vol. 63 (1982), 237-239. >> >> The Martian analemma is rather simple compared with the terrestrial case and >> resembles an asymmetrical droplet. >> >> Even more boring are the elliptical analemmas of Mercury, Venus and Jupiter. >> >> 8-shaped analemmas such as the terrestrial case are found on Saturn, Uranus, >> Neptune and Pluto. That of Saturn barely manages to form an 8 and those of >> Uranus and Pluto exhibit large north-south spans of 164 and even 180 degrees. >> >> These calculations were based on the planetary rotation parameters as they were >> known at that time and can probably be improved somewhat for the outermost >> planets as better determinations have become available. >> >> Also have a look at: >> >> http://www.analemma.com/ >> >> >> * Robert H. van Gent * Tel/Fax: 00-31-30-2720269 * >> * Zaagmolenkade 50 * E-mail: [EMAIL PROTECTED] * >> * 3515 AE Utrecht* Home page (under construction): * >> * The Netherlands* http://www.fys.ruu.nl/~vgent/ * >> > >
