NEO Discovery Statistics

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NEO Discovery Statistics

NEAR-EARTH ASTEROID DISCOVERY STATISTICS

Criteria Defining these Tables and Charts were Revised on November 30, 2006

The following charts and tables have been revised to reflect improved estimates for near-Earth asteroid (NEA) reflectivities (albedos) - and hence diameters. The absolute magnitude of a NEA (H) is a measure of the object's brightness one astronomical unit from the sun and Earth and at zero phase angle (i.e., the angle between the sun and Earth, as seen from the NEA, is zero). The absolute magnitude (H) for a particular NEA is computed from the observed apparent magnitudes of the object at various times when the phase angles and the distances from the sun and Earth are known. A value for H can then be converted to an effective diameter using an assumed value for the NEA's reflectivity (albedo). An effective diameter is the diameter of a hypothetical spherical NEA that would provide the same apparent brightness as the observed NEA, whose actual shape is unknown.

Until relatively recently, the mean albedo for NEAs was thought to be 0.11 so the corresponding absolute magnitude for a NEA whose effective diameter is one kilometer was thought to be H = 18.0. Tables and charts based upon H = 18.0 have been provided on this web site since its inception and these charts can still be viewed at the following link.

Recent work by Stuart (2003) and others have shown that NEAs are, in the mean, 20% brighter than previously thought so that the mean albedo for NEAs is 0.14 rather than 0.11. Using this revised mean albedo implies the absolute magnitude (H) for a NEA with an effective one kilometer diameter is 17.75. The charts and plots given below reflect this recent update.

Stuart, J.S. (2003). Observational Constraints on the Number, Albedos, Sizes, and Impact Hazards of the Near-Earth Asteroids. Ph.D. thesis, MIT.

All Asteroids

Table 1. NEAs Discovered by Site

Half Year Intervals	LINEAR (704)	NEAT (566,608,644)	Spacewatch (691,291)	LONEOS (699)	Catalina (703,E12,G96)	Other	Cumulative Total
1995 (1)	0	0	14	0	0	4	335
1995 (2)	0	0	12	0	0	2	349
1996 (1)	1	5	18	0	0	4	377
1996 (2)	0	5	10	0	0	2	394
1997 (1)	3	2	10	0	0	4	413
1997 (2)	14	9	4	0	0	7	447
1998 (1)	44	9	19	1	1	7	528
1998 (2)	92	2	16	6	2	6	652
1999 (1)	74	0	12	7	11	1	757
1999 (2)	87	0	7	7	19	3	880
2000 (1)	107	2	14	21	13	4	1041
2000 (2)	150	14	12	17	0	8	1242
2001 (1)	95	28	7	22	0	2	1396
2001 (2)	182	64	15	20	0	4	1681
2002 (1)	158	54	16	14	1	6	1930
2002 (2)	128	88	6	7	0	5	2164
2003 (1)	102	30	24	34	0	8	2362
2003 (2)	133	38	33	20	8	8	2602
2004 (1)	167	19	41	14	25	6	2874
2004 (2)	137	7	29	25	60	7	3139
2005 (1)	78	8	28	22	116	10	3401
2005 (2)	59	30	54	20	193	10	3767
2006 (1)	44	4	45	13	197	3	4073
2006 (2)	52	18	54	6	199	5	4407
2007 (1)	38	4	20	7	200	3	4679
2007 (2)	73	0	25	5	266	7	5055
2008 (1)	74	0	43	1	285	5	5463
2008 (2)*	5	0	2	0	35	4	5509

* Incomplete half-year (based on discovery data through 2008-Aug-13 06:00 local)

Large Asteroids
Table: Number of Near-Earth Asteroid Discoveries at Half-Year Intervals: Large Asteroids
Table 2. Large NEAs Discovered by Site

Half Year
Intervals LINEAR
(704) NEAT
(566,608,644) Spacewatch
(691,291) LONEOS
(699) Catalina
(703,E12,G96) Other Cumulative
Total

1995 (1) 0 0 3 0 0 2 174

1995 (2) 0 0 4 0 0 1 179

1996 (1) 0 2 2 0 0 0 183

1996 (2) 0 2 0 0 0 0 185

1997 (1) 0 1 2 0 0 1 189

1997 (2) 2 3 1 0 0 2 197

1998 (1) 7 4 2 1 0 1 212

1998 (2) 23 2 1 3 0 3 244

1999 (1) 17 0 2 5 3 0 271

1999 (2) 24 0 0 1 2 2 300

2000 (1) 28 2 0 1 4 1 336

2000 (2) 38 2 3 3 0 4 386

2001 (1) 24 8 0 3 0 0 421

2001 (2) 21 5 0 4 0 1 452

2002 (1) 31 4 2 3 0 1 493

2002 (2) 20 10 0 1 0 1 525

2003 (1) 15 3 1 5 0 1 550

2003 (2) 17 5 1 4 1 0 578

2004 (1) 14 5 1 2 2 1 603

2004 (2) 7 1 0 1 13 0 625

2005 (1) 10 0 2 1 9 1 648

2005 (2) 6 5 4 1 9 1 674

2006 (1) 3 0 2 1 9 0 689

2006 (2) 1 0 3 0 12 0 705

2007 (1) 2 0 3 0 9 1 720

2007 (2) 5 0 1 0 7 0 733

2008 (1) 2 0 1 0 9 0 745

2008 (2)* 0 0 0 0 3 0 748

* Incomplete half-year (based on discovery data through 2008-Aug-13 06:00 local)

Data compiled by Alan Chamberlin.

NUMBER OF NEOS

NASA's search program designed to discover 90% of the NEO population (1 km in diameter or larger) within 10 years is under way. The chart below shows the cumulative total known near-Earth asteroids versus time.

The blue area shows all near-Earth asteroids while the red area shows only large near-Earth asteroids (those with diameters roughly one kilometer and larger).
The table below shows the total number of NEOs known at selected dates. The most recent date at the top of the table is generally not the date the table was updated, but rather the discovery date of the most recently discovered NEO. This table is updated daily using discovery data published by the Minor Planet Center.

------------------------------------------------------------------ Date NEC Aten Apollo Amor PHA-KM PHA NEA-KM NEA NEO ---------- ---- ---- ------ ---- ------ ---- ------ ---- ---- 2008-08-19 65 462 2945 2094 140 961 749 5510 5575 2008-08-01 65 461 2935 2089 140 958 749 5494 5559 2008-07-01 65 459 2917 2078 139 949 746 5463 5528 2008-06-01 65 455 2906 2070 139 946 745 5440 5505 2008-05-01 65 451 2875 2052 139 939 744 5387 5452 2008-04-01 65 449 2827 2022 139 936 743 5307 5372 2008-03-01 65 440 2759 1997 138 927 736 5204 5269 2008-02-01 65 428 2699 1967 137 913 734 5102 5167 2008-01-01 65 426 2671 1950 137 904 734 5055 5120 2007-12-01 65 423 2636 1934 137 895 731 5001 5066 2007-11-01 65 411 2577 1899 137 885 727 4895 4960 2007-10-01 64 397 2528 1857 137 873 726 4790 4854 2007-09-01 64 390 2490 1825 136 866 725 4713 4777 2007-08-01 64 388 2479 1815 135 861 721 4690 4754 2007-07-01 64 388 2475 1808 135 860 721 4679 4743 2007-06-01 64 383 2454 1798 134 851 718 4643 4707 2007-05-01 64 382 2442 1786 134 847 716 4618 4682 2007-04-01 64 381 2417 1769 134 843 713 4575 4639 2007-03-01 64 375 2377 1746 134 836 711 4505 4569 2007-02-01 64 367 2344 1730 133 829 707 4448 4512 2007-01-01 64 359 2324 1717 133 820 706 4407 4471 2006-12-01 64 354 2297 1699 133 817 704 4357 4421 2006-11-01 63 344 2248 1676 132 805 697 4274 4337 2006-10-01 61 337 2218 1644 132 795 695 4205 4266 2006-09-01 61 330 2181 1617 131 786 691 4134 4195 2006-08-01 61 328 2164 1604 131 781 691 4102 4163 2006-07-01 61 327 2153 1587 131 779 690 4073 4134 2006-06-01 61 326 2142 1574 131 776 690 4048 4109 2006-05-01 61 325 2114 1547 131 767 686 3991 4052 2006-04-01 60 321 2087 1532 131 757 684 3945 4005 2006-03-01 60 319 2071 1513 131 756 683 3908 3968 2006-02-01 60 316 2036 1496 131 748 680 3853 3913 2006-01-01 60 312 1979 1471 130 739 675 3767 3827 2005-12-01 60 302 1947 1450 129 728 672 3704 3764 2005-11-01 60 297 1905 1424 128 718 668 3631 3691 2005-10-01 59 289 1849 1384 127 705 658 3526 3585 2005-09-01 59 286 1815 1365 127 700 655 3470 3529 2005-08-01 59 283 1801 1348 127 694 652 3436 3495 2005-07-01 59 279 1782 1336 126 687 649 3401 3460 2005-06-01 59 275 1767 1316 126 683 644 3362 3421 2005-05-01 58 274 1751 1300 124 677 641 3329 3387 2005-04-01 58 268 1725 1282 122 664 637 3279 3337 2005-03-01 58 263 1685 1257 121 654 633 3209 3267 2005-02-01 58 262 1661 1250 120 650 630 3177 3235 2005-01-01 58 258 1637 1240 120 643 626 3139 3197 2004-12-01 57 249 1605 1218 120 634 618 3075 3132 2004-11-01 57 245 1585 1212 119 625 613 3045 3102 2004-10-01 56 238 1557 1204 118 614 611 3002 3058 2004-09-01 55 230 1519 1179 118 606 611 2931 2986 2004-08-01 55 226 1500 1156 117 599 607 2885 2940 2004-07-01 55 226 1494 1151 115 596 604 2874 2929 2004-06-01 55 223 1464 1138 114 585 601 2828 2883 2004-05-01 55 218 1445 1123 114 579 598 2788 2843 2004-04-01 55 215 1415 1111 110 569 591 2743 2798 2004-03-01 55 206 1379 1093 110 562 584 2680 2735 2004-02-01 54 204 1364 1086 109 557 583 2656 2710 2004-01-01 54 202 1330 1068 107 547 579 2602 2656 2003-12-01 54 196 1298 1056 105 534 572 2552 2606 2003-11-01 54 193 1276 1043 105 526 566 2514 2568 2003-10-01 54 188 1249 1021 105 518 564 2460 2514 2003-09-01 54 185 1229 988 103 509 558 2404 2458 2003-08-01 54 185 1217 975 100 504 554 2379 2433 2003-07-01 53 184 1210 966 100 502 551 2362 2415 2003-06-01 53 182 1194 955 100 497 546 2333 2386 2003-05-01 51 180 1180 948 99 495 544 2310 2361 2003-04-01 51 175 1160 936 99 488 540 2273 2324 2003-03-01 51 170 1141 925 99 481 536 2238 2289 2003-02-01 51 169 1121 919 99 476 532 2210 2261 2003-01-01 51 167 1094 902 98 466 526 2164 2215 2002-12-01 51 163 1067 882 98 464 524 2113 2164 2002-11-01 51 160 1052 865 97 458 520 2078 2129 2002-10-01 50 158 1028 841 96 452 511 2028 2078 2002-09-01 50 155 1008 822 95 446 503 1986 2036 2002-08-01 50 154 992 800 93 435 499 1947 1997 2002-07-01 49 152 983 794 92 429 494 1930 1979 2002-06-01 49 148 965 786 90 421 488 1900 1949 2002-05-01 49 144 947 775 89 412 478 1867 1916 2002-04-01 49 142 929 763 89 405 476 1835 1884 2002-03-01 48 136 902 750 88 395 472 1789 1837 2002-02-01 48 131 879 734 87 386 462 1745 1793 2002-01-01 48 124 844 712 87 373 453 1681 1729 2001-12-01 48 121 807 694 83 359 445 1623 1671 2001-11-01 46 120 779 679 82 351 441 1579 1625 2001-10-01 46 114 753 656 81 341 437 1524 1570 2001-09-01 46 110 724 623 80 330 426 1458 1504 2001-08-01 45 109 702 603 80 324 424 1415 1460 2001-07-01 44 108 697 590 80 323 422 1396 1440 2001-06-01 43 108 687 579 78 320 414 1375 1418 2001-05-01 42 107 675 568 76 313 406 1351 1393 2001-04-01 42 105 663 559 75 305 403 1328 1370 2001-03-01 42 101 648 545 73 296 395 1295 1337 2001-02-01 42 98 637 534 72 293 390 1270 1312 2001-01-01 42 94 622 525 72 290 386 1242 1284 2000-12-01 42 93 608 513 71 284 380 1215 1257 2000-11-01 42 90 584 496 70 281 371 1171 1213 2000-10-01 42 87 574 482 70 277 363 1144 1186 2000-09-01 42 81 556 456 69 271 354 1094 1136 2000-08-01 42 79 538 440 67 262 345 1058 1100 2000-07-01 42 77 533 430 65 259 336 1041 1083 2000-06-01 42 76 528 424 64 255 333 1029 1071 2000-05-01 42 76 515 410 64 250 328 1002 1044 2000-04-01 41 73 500 397 63 244 321 971 1012 2000-03-01 41 64 484 387 61 232 311 936 977 2000-02-01 41 62 467 376 61 222 304 906 947 2000-01-01 41 57 454 368 61 215 300 880 921 1999-12-01 41 56 444 359 59 207 293 860 901 1999-11-01 41 54 431 345 59 203 284 831 872 1999-10-01 41 54 415 331 58 198 279 801 842 1999-09-01 40 54 398 316 57 192 275 769 809 1999-08-01 40 54 398 314 57 192 275 767 807 1999-07-01 40 54 393 309 56 190 271 757 797 1999-06-01 40 51 386 299 55 185 268 737 777 1999-05-01 40 49 374 293 51 177 258 717 757 1999-04-01 40 48 361 286 50 173 251 696 736 1999-03-01 40 47 351 281 50 172 250 680 720 1999-02-01 40 47 341 276 50 169 247 665 705 1999-01-01 40 45 336 270 50 166 244 652 692 1998-12-01 40 41 326 261 50 162 236 629 669 1998-11-01 40 38 309 253 48 154 231 601 641 1998-10-01 40 36 304 247 48 152 227 588 628 1998-09-01 40 29 291 234 47 140 221 555 595 1998-08-01 40 29 281 223 45 133 215 534 574 1998-07-01 40 29 278 220 43 129 212 528 568 1998-06-01 40 29 272 213 42 127 209 515 555 1998-05-01 40 29 263 207 42 124 205 500 540 1998-04-01 40 27 255 198 42 117 204 481 521 1998-03-01 40 27 243 190 42 112 200 461 501 1998-02-01 40 26 239 190 42 110 200 455 495 1998-01-01 40 26 234 187 42 108 197 447 487 1997-01-01 40 22 205 167 40 97 185 394 434 1996-01-01 40 20 177 152 38 86 179 349 389 1995-01-01 40 19 163 135 37 83 169 317 357 1994-01-01 38 15 140 116 33 70 152 271 309 1993-01-01 38 13 117 100 31 64 138 230 268 1992-01-01 38 11 103 85 29 61 122 199 237 1991-01-01 36 9 76 74 24 49 106 159 195 1990-01-01 36 8 63 63 20 42 90 134 170 1980-01-01 33 3 27 23 12 17 45 53 86 1970-01-01 31 0 13 14 8 10 24 27 58 1960-01-01 30 0 10 10 7 8 18 20 50 1950-01-01 30 0 7 6 4 5 12 13 43 1940-01-01 26 0 3 6 2 3 8 9 35 1930-01-01 25 0 0 5 0 0 5 5 30 1920-01-01 23 0 0 3 0 0 3 3 26 1910-01-01 22 0 0 1 0 0 1 1 23 1900-01-01 20 0 0 1 0 0 1 1 21

Note: "NEC" are Near-Earth comets. "PHA-KM" and "NEA-KM" are PHAs and NEAs with diameters roughly one kilometer and larger.

Data compiled by Alan Chamberlin.

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