| THE ASTRO COMPASS |
| Here is a PDF file that on a couple of pages shows how to use the astro compass to determine true north, and examples are given. Two methods are shown. The illustratingShadows.xls spreadsheet (in the zip file to the left) supports the second method. The astro compass can also be used to tell the time accurately, being a variation of the armillary dial. A quick stand alone spreadsheet for the Astro Compass is here in Excel form. The best spreadsheet is my main one however, see Excel page. CLICK HERE for the astro compass notes. [NOTE: the examples are set in New Mexico and AZ, USA as regards longitude] I have had these things on and off since I was a late teen, as well as bubble and fixed horizon sextants, and almost anything that came out of world war 2 ships and planes. They can be found on Ebay fairly easily for less than $100, and these notes tell you how to use it, and tell how to make the mount out of a bit of PVC pipe. Without that mount, the levelling system will not work. I have Excel sheets for the PC as well as Documents To Go to facilitate astro compass usage. Anyhow, after you have seen some of these articles on this web site, you may want to purchase the book itself, Illustrating Time's Shadow (printed, or online download) buy here! |
| Hour of day from 0600 to 1800 converted to degrees STANDARD TIME (not summer time) 6 7 8 9 10 11 12 13 14 15 16 17 mins 0 270 285 300 315 330 345 0 15 30 45 60 75 4 271 286 301 316 331 346 1 16 31 46 61 76 8 272 287 302 317 332 347 2 17 32 47 62 77 12 273 288 303 318 333 348 3 18 33 48 63 78 16 274 289 304 319 334 349 4 19 34 49 64 79 20 275 290 305 320 335 350 5 20 35 50 65 80 24 276 291 306 321 336 351 6 21 36 51 66 81 28 277 292 307 322 337 352 7 22 37 52 67 82 32 278 293 308 323 338 353 8 23 38 53 68 83 36 279 294 309 324 339 354 9 24 39 54 69 84 40 280 295 310 325 340 355 10 25 40 55 70 85 44 281 296 311 326 341 356 11 26 41 56 71 86 48 282 297 312 327 342 357 12 27 42 57 72 87 52 283 298 313 328 343 358 13 28 43 58 73 88 56 284 299 314 329 344 359 14 29 44 59 74 89 60 285 300 315 330 345 360 15 30 45 60 75 90 This table comes from a spreadsheet which allows you to adjust the astro compass hour angle for longitude and EOT. The master spreadsheet (Excel)has this and other valuable sheets. There is also a version specifically for the Palm Pilot. Only two adjustments (which the main spreadsheet does for you), one is to correct for longitude offset from the standard time meridian, the other is the EOT. |
