+---+ | J | +---+ JULIAN CALENDAR (noun) 45 B.C., Julius Caesar introduces a new "Julian" calendar of 365.25 days in which the first day of the year is January 1. He has commissioned the Greek astronomer-mathematician Sosigenes of Alexandria to reform the calendar (see 153 B.C.; A.D. 1582). (PC) The solar calendar introduced by Julius Caesar in Rome in 46 B.C., having a year of 12 months and 365 days and a leap year of 366 days every fourth year. It was eventually replaced by the Gregorian calendar. (AH) The Julian calendar, under which Western nations measured time until A.D. 1582, was authorized by Julius Caesar in 46 B.C., the year 709 of Rome. His expert was a Greek, Sosigenes. The Julian calendar, on the assumption that the true year was 365 1/4 days, gave every fourth year 366 days. Julian Calendar Year (last 2 Figures of Desired Year) 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 Century 00 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 0 700 1400 12 7 1 2 10 5 6 7 8 3 4 5 13 1 2 3 11 6 7 1 9 4 5 6 14 2 3 4 12 100 800 1500 11 6 7 1 9 4 5 6 14 2 3 4 12 7 1 2 10 5 6 7 8 3 4 5 13 1 2 3 11 200 900 1600 10 5 6 7 8 3 4 5 13 1 2 3 11 6 7 1 9 4 5 6 14 2 3 4 12 7 1 2 10 300 1000 1700 9 4 5 6 14 2 3 4 12 7 1 2 10 5 6 7 8 3 4 5 13 1 2 3 11 6 7 1 9 400 1100 1800 8 3 4 5 13 1 2 3 11 6 7 1 9 4 5 6 14 2 3 4 12 7 1 2 10 5 6 7 8 500 1200 1900 14 2 3 4 12 7 1 2 10 5 6 7 8 3 4 5 13 1 2 3 11 6 7 1 9 4 5 6 14 600 1300 2000 13 1 2 3 11 6 7 1 9 4 5 6 14 2 3 4 12 7 1 2 10 5 6 7 8 3 4 5 13 (FW) JULIAN DATE. As a general term used widely in computer programming and this document: A date in the format YYDDD. A date format that contains the year in positions 1 and 2, and the day in positions 3 through 5. The day is represented as 1 through 366, right adjusted, padded with zeroes on the left. For example, 1996-August-29 is 96242. However, the above definition is accurately referred to as the ORDINAL DAY OF YEAR date, see JULIAN DAY NUMBER. (IBM) JULIAN DAY NUMBER: The astronomal system that counts the days since the First of January in the year 4713 BCE (the year -4712 before the common era). This scheme was invented by the astronomer Joseph Scaliger in the 16th century and named by him for his father Julius. The leap year reforms implicit in the new scheme were adopted at the command of Pope Gregory XIII in the year 1582 - hence the Gregorian Calendar. The Gregorian, or New Style, calendar was adopted in Britain and their colonies in September of 1752. (September of that year was missing 11 days. The 14th followed the 2nd.) The remainder left when dividing the Julian Day Number by 7 indicates the day of week of the specified date. Zero corresponds to Monday, 1 to Tuesday, up through 6 for Sunday. For example, 1996-Aug-29 is equivalent to Julian Day 2450325. Further, the hour of the day is expressed as a decimal such that 2450325.5 is midnight 1996-Aug-29, based on the fact that a Julian Day begins at mid-day (noon). (IBM) JULIAN PERIOD or JULIAN DAY How many days have you lived? To determine this, you must multiply your age by 365, add the number of days since your last birthday until today, and account for all leap years. Chances are your answer would be wrong. Astronomers, however, find it convenient to express dates and long time intervals in days rather than in years, months, and days. This is done by placing events within the Julian period. The Julian period was devised in 1582 by the French classical scholar Joseph Scaliger (1540-1609) and named after his father Julius Caesar Scaliger (1484-1558), not after the Julian calendar. Joseph Scaliger began Julian Day (JD) #1 at noon, Jan. 1, 4713 B.C., the most recent time that 3 major chronological cycles began on the same day- (1) the 28-year solar cycle, after which dates in the Julian calendar (e.g., Feb. 11) return to the same days of the week (e.g., Monday); (2) the 19-year lunar cycle, after which the phases of the moon return to the same dates of the year; and (3) the 15-year indiction cycle, used in ancient Rome to regulate taxes. It will take 7,980 years to complete the period, the product of 28, 19, and 15. Noon of Dec. 31, 1994, marks the beginning of JD 2,449,718; that many days will have passed since the start of the Julian period. The JD at noon of any date in 1995 may be found by adding to this figure the day of the year for that date, which is given in the left most column in the chart below. Simple JD conversion tables are used by astronomers. (FW) Days Between Two Dates Table covers period of 2 ordinary years. Example-Days between Feb. 10, 1989, and Dec. 15, 1990; subtract 41 from 714; answer is 673 days. For leap year, such as 1992, one day must be added: final answer is 674. Date Jan. Feb. Mar. Apr. May June July Aug. Sept. Oct. Nov. Dec. 1 1 32 60 91 121 152 182 213 244 274 305 335 2 2 33 61 92 122 153 183 214 245 275 306 336 3 3 34 62 93 123 154 184 215 246 276 307 337 4 4 35 63 94 124 155 185 216 247 277 308 338 5 5 36 64 95 125 156 186 217 248 278 309 339 6 6 37 65 96 126 157 187 218 249 279 310 340 7 7 38 66 97 127 158 188 219 250 280 311 341 8 8 39 67 98 128 159 189 220 251 281 312 342 9 9 40 68 99 129 160 190 221 252 282 313 343 10 10 41 69 100 130 161 191 222 253 283 314 344 11 11 42 70 101 131 162 192 223 254 284 315 345 12 12 43 71 102 132 163 193 224 255 285 316 346 13 13 44 72 103 133 164 194 225 256 286 317 347 14 14 45 73 104 134 165 195 226 257 287 318 348 15 15 46 74 105 135 166 196 227 258 288 319 349 16 16 47 75 106 136 167 197 228 259 289 320 350 17 17 48 76 107 137 168 198 229 260 290 321 351 18 18 49 77 108 138 169 199 230 261 291 322 352 19 19 50 78 109 139 170 200 231 262 292 323 353 20 20 51 79 110 140 171 201 232 263 293 324 354 21 21 52 80 111 141 172 202 233 264 294 325 355 22 22 53 81 112 142 173 203 234 265 295 326 356 23 23 54 82 113 143 174 204 235 266 296 327 357 24 24 55 83 114 144 175 205 236 267 297 328 358 25 25 56 84 115 145 176 206 237 268 298 329 359 26 26 57 85 116 146 177 207 238 269 299 330 360 27 27 58 86 117 147 178 208 239 270 300 331 361 28 28 59 87 118 148 179 209 240 271 301 332 362 29 29 - 88 119 149 180 210 241 272 302 333 363 30 30 - 89 120 150 181 211 242 273 303 334 364 31 31 - 90 - 151 - 212 243 - 304 - 365 Date Jan. Feb. Mar. Apr. May June July Aug. Sept. Oct. Nov. Dec. 1 366 397 425 456 486 517 547 578 609 639 670 700 2 367 398 426 457 487 518 548 579 610 640 671 701 3 368 399 427 458 488 519 549 580 611 641 672 702 4 369 400 428 459 489 520 550 581 612 642 673 703 5 370 401 429 460 490 521 551 582 613 643 674 704 6 371 402 430 461 491 522 552 583 614 644 675 705 7 372 403 431 462 492 523 553 584 615 645 676 706 8 373 404 432 463 493 524 554 585 616 646 677 707 9 374 405 433 464 494 525 555 586 617 647 678 708 10 375 406 434 465 495 526 556 587 618 648 679 709 11 376 407 435 466 496 527 557 588 619 649 680 710 12 377 408 436 467 497 528 558 589 620 650 681 711 13 378 409 437 468 498 529 559 590 621 651 682 712 14 379 410 438 469 499 530 560 591 622 652 683 713 15 380 411 439 470 500 531 561 592 623 653 684 714 16 381 412 440 471 501 532 562 593 624 654 685 715 17 382 413 441 472 502 533 563 594 625 655 686 716 18 383 414 442 473 503 534 564 595 626 656 687 717 19 384 415 443 474 504 535 565 596 627 657 688 718 20 385 416 444 475 505 536 566 597 628 658 689 719 21 386 417 445 476 506 537 567 598 629 659 690 720 22 387 418 446 477 507 538 568 599 630 660 691 721 23 388 419 447 478 508 539 569 600 631 661 692 722 24 389 420 448 479 509 540 570 601 632 662 693 723 25 390 421 449 480 510 541 571 602 633 663 694 724 26 391 422 450 481 511 542 572 603 634 664 695 725 27 392 423 451 482 512 543 573 604 635 665 696 726 28 393 424 452 483 513 544 574 605 636 666 697 727 29 394 - 453 484 514 545 575 606 637 667 698 728 30 395 - 454 485 515 546 576 607 638 668 699 729 31 396 - 455 - 516 - 577 608 - 669 - 730 (FW)