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)	108	2	14	21	13	4	1042
2000 (2)	150	14	12	17	0	8	1243
2001 (1)	95	28	7	22	0	2	1397
2001 (2)	183	64	15	20	0	4	1683
2002 (1)	158	54	16	14	1	6	1932
2002 (2)	128	88	6	7	0	5	2166
2003 (1)	102	30	24	34	0	9	2365
2003 (2)	133	38	33	20	8	8	2605
2004 (1)	167	19	41	14	24	6	2876
2004 (2)	137	7	29	25	60	6	3140
2005 (1)	78	8	28	22	116	10	3402
2005 (2)	59	30	54	19	193	10	3767
2006 (1)	44	4	45	13	197	3	4073
2006 (2)	52	18	54	6	200	5	4408
2007 (1)	38	4	20	7	200	3	4680
2007 (2)	73	0	25	5	266	7	5056
2008 (1)	74	0	43	1	283	5	5462
2008 (2)	67	0	43	0	278	11	5861
2009 (1)	50	0	32	0	263	18	6224
2009 (2)*	34	0	22	0	200	15	6495

* Incomplete half-year (based on discovery data through 2009-Oct-31 06:05 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 2 177

1995 (2) 0 0 4 0 0 1 182

1996 (1) 0 2 2 0 0 0 186

1996 (2) 0 2 0 0 0 0 188

1997 (1) 0 1 2 0 0 1 192

1997 (2) 2 3 1 0 0 2 200

1998 (1) 8 4 2 1 0 2 217

1998 (2) 24 2 1 3 0 3 250

1999 (1) 17 0 2 5 3 0 277

1999 (2) 24 0 0 1 2 2 306

2000 (1) 30 2 0 1 4 1 344

2000 (2) 39 2 3 5 0 4 397

2001 (1) 24 8 0 3 0 0 432

2001 (2) 22 5 0 4 0 1 464

2002 (1) 32 4 2 3 0 1 506

2002 (2) 20 10 0 1 0 1 538

2003 (1) 16 3 1 6 0 2 566

2003 (2) 17 5 1 4 1 1 595

2004 (1) 15 5 1 2 2 1 621

2004 (2) 8 1 0 1 13 0 644

2005 (1) 10 0 2 1 9 1 667

2005 (2) 6 5 5 0 9 1 693

2006 (1) 3 0 2 1 9 0 708

2006 (2) 1 0 3 0 12 0 724

2007 (1) 2 0 3 0 9 1 739

2007 (2) 5 0 1 0 7 0 752

2008 (1) 2 0 1 0 9 0 764

2008 (2) 3 0 1 0 6 0 774

2009 (1) 1 0 1 0 8 0 784

2009 (2)* 5 0 0 0 4 2 795

* Incomplete half-year (based on discovery data through 2009-Oct-31 06:05 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).

(click on the chart above for a larger version)

The chart below shows the total known near-Earth asteroids per size bin. Diameters are estimated using an assumed average albedo for NEAs. The first size bin represents NEAs smaller than 30m in diameter. The second represents NEAs with diameters from 30m to 100m, and so on.

Known Near-Earth Asteroids by Size Bin
Data shown in the chart above represent known NEAs as of the date shown in the bottom-right corner of the chart.

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 Atira Aten Apollo Amor PHA-KM PHA NEA-KM NEA NEO ---------- ---- ----- ---- ------ ---- ------ ---- ------ ---- ---- 2009-11-06 84 10 520 3497 2469 146 1070 795 6496 6580 2009-11-01 84 10 520 3496 2469 146 1070 795 6495 6579 2009-10-01 84 10 511 3440 2436 145 1066 792 6397 6481 2009-09-01 84 10 506 3387 2389 145 1056 790 6292 6376 2009-08-01 84 10 504 3367 2362 145 1054 788 6243 6327 2009-07-01 84 10 504 3357 2353 144 1052 784 6224 6308 2009-06-01 83 10 501 3345 2342 143 1049 783 6198 6281 2009-05-01 83 10 499 3318 2329 143 1040 781 6156 6239 2009-04-01 83 10 496 3287 2314 143 1035 779 6107 6190 2009-03-01 83 10 491 3228 2291 143 1023 779 6020 6103 2009-02-01 83 10 487 3172 2263 142 1011 776 5932 6015 2009-01-01 83 10 481 3128 2242 142 1002 774 5861 5944 2008-12-01 82 10 480 3086 2212 142 991 773 5788 5870 2008-11-01 82 10 474 3038 2190 142 983 771 5712 5794 2008-10-01 82 9 467 2977 2140 141 974 770 5593 5675 2008-09-01 81 9 464 2946 2106 141 964 768 5525 5606 2008-08-01 81 9 461 2931 2092 141 958 767 5493 5574 2008-07-01 81 9 459 2913 2081 140 949 764 5462 5543 2008-06-01 81 9 455 2902 2073 140 946 763 5439 5520 2008-05-01 81 9 451 2872 2055 140 940 762 5387 5468 2008-04-01 81 9 449 2824 2026 140 937 761 5308 5389 2008-03-01 81 8 440 2756 2001 139 928 754 5205 5286 2008-02-01 81 8 428 2696 1971 138 914 752 5103 5184 2008-01-01 81 8 426 2668 1954 138 905 752 5056 5137 2007-12-01 81 8 423 2633 1938 138 895 749 5002 5083 2007-11-01 81 8 411 2574 1903 138 885 745 4896 4977 2007-10-01 80 8 397 2525 1861 138 874 744 4791 4871 2007-09-01 80 8 390 2487 1829 137 867 743 4714 4794 2007-08-01 80 8 388 2476 1819 136 862 739 4691 4771 2007-07-01 80 8 388 2472 1812 136 861 739 4680 4760 2007-06-01 80 8 383 2451 1802 135 852 736 4644 4724 2007-05-01 80 8 382 2439 1790 135 848 734 4619 4699 2007-04-01 80 8 381 2414 1773 135 844 731 4576 4656 2007-03-01 80 7 375 2374 1750 135 837 729 4506 4586 2007-02-01 80 7 367 2341 1734 134 829 725 4449 4529 2007-01-01 80 7 359 2321 1721 134 820 724 4408 4488 2006-12-01 79 7 354 2294 1703 134 817 722 4358 4437 2006-11-01 79 6 344 2245 1679 133 805 715 4274 4353 2006-10-01 77 6 337 2215 1647 133 795 713 4205 4282 2006-09-01 77 6 330 2178 1620 132 786 709 4134 4211 2006-08-01 77 6 328 2161 1607 132 781 709 4102 4179 2006-07-01 77 6 327 2150 1590 132 779 708 4073 4150 2006-06-01 77 6 326 2139 1577 132 776 708 4048 4125 2006-05-01 77 5 325 2111 1550 132 766 704 3991 4068 2006-04-01 76 5 321 2084 1535 132 756 702 3945 4021 2006-03-01 76 5 319 2068 1516 132 755 701 3908 3984 2006-02-01 76 5 316 2033 1499 132 747 698 3853 3929 2006-01-01 76 5 312 1977 1473 131 738 693 3767 3843 2005-12-01 76 5 302 1945 1452 130 727 690 3704 3780 2005-11-01 76 5 297 1903 1426 129 717 686 3631 3707 2005-10-01 75 4 289 1847 1386 128 704 675 3526 3601 2005-09-01 75 4 286 1813 1367 128 699 672 3470 3545 2005-08-01 75 4 283 1799 1351 128 693 670 3437 3512 2005-07-01 75 4 279 1780 1339 127 686 667 3402 3477 2005-06-01 75 4 275 1765 1319 127 682 662 3363 3438 2005-05-01 74 4 274 1749 1303 125 676 659 3330 3404 2005-04-01 74 4 268 1723 1285 123 663 655 3280 3354 2005-03-01 74 4 263 1683 1260 122 653 651 3210 3284 2005-02-01 74 4 262 1659 1253 121 649 648 3178 3252 2005-01-01 74 4 258 1635 1243 121 642 644 3140 3214 2004-12-01 73 3 249 1603 1222 121 633 636 3077 3150 2004-11-01 73 3 245 1583 1216 120 624 631 3047 3120 2004-10-01 72 3 238 1555 1208 119 613 629 3004 3076 2004-09-01 71 3 230 1517 1183 119 605 628 2933 3004 2004-08-01 71 3 226 1498 1160 118 598 624 2887 2958 2004-07-01 71 3 226 1492 1155 116 595 621 2876 2947 2004-06-01 71 3 223 1462 1142 115 584 618 2830 2901 2004-05-01 71 2 218 1443 1127 115 578 615 2790 2861 2004-04-01 71 2 215 1413 1115 111 568 608 2745 2816 2004-03-01 71 2 206 1377 1097 111 561 600 2682 2753 2004-02-01 70 2 204 1362 1091 110 556 599 2659 2729 2004-01-01 70 2 202 1328 1073 108 546 595 2605 2675 2003-12-01 70 2 196 1296 1061 106 534 588 2555 2625 2003-11-01 70 2 193 1274 1048 106 526 582 2517 2587 2003-10-01 70 2 188 1247 1026 106 517 580 2463 2533 2003-09-01 70 2 185 1227 993 104 508 573 2407 2477 2003-08-01 70 2 185 1215 980 101 503 569 2382 2452 2003-07-01 69 2 184 1208 971 101 501 566 2365 2434 2003-06-01 69 2 182 1192 959 101 496 560 2335 2404 2003-05-01 67 2 180 1178 952 100 494 558 2312 2379 2003-04-01 67 2 175 1158 940 100 487 553 2275 2342 2003-03-01 67 2 170 1139 929 100 480 549 2240 2307 2003-02-01 67 1 169 1119 923 100 475 545 2212 2279 2003-01-01 67 1 167 1092 906 99 465 538 2166 2233 2002-12-01 67 1 163 1065 886 99 463 536 2115 2182 2002-11-01 67 1 160 1050 869 98 457 532 2080 2147 2002-10-01 66 1 158 1026 845 97 451 523 2030 2096 2002-09-01 64 1 155 1006 826 96 445 515 1988 2052 2002-08-01 64 1 154 990 804 94 434 511 1949 2013 2002-07-01 63 1 152 981 798 93 428 506 1932 1995 2002-06-01 63 1 148 963 790 91 420 500 1902 1965 2002-05-01 63 1 144 945 779 90 411 489 1869 1932 2002-04-01 63 1 142 927 767 90 404 487 1837 1900 2002-03-01 62 1 136 900 754 89 394 483 1791 1853 2002-02-01 62 1 131 877 738 88 385 473 1747 1809 2002-01-01 62 1 124 842 716 88 372 464 1683 1745 2001-12-01 62 1 121 805 698 84 358 455 1625 1687 2001-11-01 60 1 120 778 682 83 350 451 1581 1641 2001-10-01 60 1 114 752 659 82 340 447 1526 1586 2001-09-01 60 1 110 723 625 81 329 436 1459 1519 2001-08-01 59 1 109 701 605 81 323 434 1416 1475 2001-07-01 58 1 108 696 592 81 322 432 1397 1455 2001-06-01 57 1 108 686 581 79 319 425 1376 1433 2001-05-01 56 1 107 674 570 77 312 417 1352 1408 2001-04-01 56 1 105 662 561 76 304 414 1329 1385 2001-03-01 56 1 101 647 547 74 295 406 1296 1352 2001-02-01 56 1 98 636 536 73 292 401 1271 1327 2001-01-01 56 1 94 621 527 73 289 397 1243 1299 2000-12-01 56 1 93 607 515 72 283 390 1216 1272 2000-11-01 56 1 90 583 498 71 280 381 1172 1228 2000-10-01 56 1 87 573 484 71 276 373 1145 1201 2000-09-01 56 1 81 555 458 70 270 364 1095 1151 2000-08-01 56 1 79 537 442 68 261 355 1059 1115 2000-07-01 56 1 77 532 432 66 258 344 1042 1098 2000-06-01 56 1 76 527 426 65 254 341 1030 1086 2000-05-01 56 1 76 514 412 65 249 336 1003 1059 2000-04-01 55 1 73 499 399 64 243 329 972 1027 2000-03-01 55 1 64 483 388 62 231 318 936 991 2000-02-01 55 1 62 466 377 62 221 311 906 961 2000-01-01 55 1 57 452 370 62 214 306 880 935 1999-12-01 54 1 56 442 361 60 206 299 860 914 1999-11-01 54 1 54 429 347 60 202 290 831 885 1999-10-01 54 1 54 413 333 59 197 285 801 855 1999-09-01 52 1 54 396 318 58 191 281 769 821 1999-08-01 52 1 54 396 316 58 191 281 767 819 1999-07-01 52 1 54 391 311 57 189 277 757 809 1999-06-01 52 1 51 384 301 56 185 274 737 789 1999-05-01 52 1 49 372 295 52 177 264 717 769 1999-04-01 52 1 48 359 288 51 173 257 696 748 1999-03-01 52 1 47 349 283 51 172 256 680 732 1999-02-01 52 1 47 339 278 51 169 253 665 717 1999-01-01 52 1 45 334 272 51 166 250 652 704 1998-12-01 52 1 41 324 263 51 162 241 629 681 1998-11-01 52 1 38 307 255 49 154 236 601 653 1998-10-01 52 1 36 302 249 49 152 232 588 640 1998-09-01 52 1 29 289 236 48 140 226 555 607 1998-08-01 52 1 29 279 225 46 133 220 534 586 1998-07-01 52 1 29 276 222 44 129 217 528 580 1998-06-01 52 1 29 270 215 43 127 213 515 567 1998-05-01 52 1 29 261 209 43 124 209 500 552 1998-04-01 52 1 27 253 200 43 117 208 481 533 1998-03-01 52 1 27 241 192 43 112 204 461 513 1998-02-01 52 0 26 237 192 42 110 203 455 507 1998-01-01 52 0 26 232 189 42 108 200 447 499 1997-01-01 52 0 22 203 169 40 97 188 394 446 1996-01-01 52 0 20 176 153 38 86 182 349 401 1995-01-01 52 0 19 162 136 37 83 172 317 369 1994-01-01 50 0 15 139 117 33 70 155 271 321 1993-01-01 50 0 13 116 101 31 64 141 230 280 1992-01-01 50 0 11 102 86 29 61 124 199 249 1991-01-01 48 0 9 75 75 24 49 107 159 207 1990-01-01 48 0 8 62 64 20 42 91 134 182 1980-01-01 44 0 3 27 23 12 17 45 53 97 1970-01-01 42 0 0 13 14 8 10 24 27 69 1960-01-01 41 0 0 10 10 7 8 18 20 61 1950-01-01 41 0 0 7 6 4 5 12 13 54 1940-01-01 36 0 0 3 6 2 3 8 9 45 1930-01-01 34 0 0 0 5 0 0 5 5 39 1920-01-01 32 0 0 0 3 0 0 3 3 35 1910-01-01 30 0 0 0 1 0 0 1 1 31 1900-01-01 28 0 0 0 1 0 0 1 1 29

Note: "NEC" are Near-Earth comets. "PHA-KM" and "NEA-KM" are PHAs and NEAs with diameters roughly one kilometer and larger. Other definitions, such as Apollo, are on the NEO groups page.

Data compiled by Alan Chamberlin.

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