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	8	2364
2003 (2)	133	38	33	20	8	8	2604
2004 (1)	167	19	41	14	25	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)*	5	0	2	0	8	6	6245

* Incomplete half-year (based on discovery data through 2009-Aug-06 21:00 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 2 176

1995 (2) 0 0 4 0 0 1 181

1996 (1) 0 2 2 0 0 0 185

1996 (2) 0 2 0 0 0 0 187

1997 (1) 0 1 2 0 0 1 191

1997 (2) 2 3 1 0 0 2 199

1998 (1) 8 4 2 1 0 2 216

1998 (2) 23 2 1 3 0 3 248

1999 (1) 17 0 2 5 3 0 275

1999 (2) 24 0 0 1 2 2 304

2000 (1) 30 2 0 1 4 1 342

2000 (2) 39 2 3 4 0 4 394

2001 (1) 24 8 0 3 0 0 429

2001 (2) 22 5 0 4 0 1 461

2002 (1) 32 4 2 3 0 1 503

2002 (2) 20 10 0 1 0 1 535

2003 (1) 16 3 1 6 0 1 562

2003 (2) 17 5 1 4 1 1 591

2004 (1) 15 5 1 2 2 1 617

2004 (2) 8 1 0 1 13 0 640

2005 (1) 10 0 2 1 9 1 663

2005 (2) 6 5 5 0 9 1 689

2006 (1) 3 0 2 1 9 0 704

2006 (2) 1 0 3 0 12 0 720

2007 (1) 2 0 3 0 9 1 735

2007 (2) 5 0 1 0 7 0 748

2008 (1) 2 0 1 0 9 0 760

2008 (2) 3 0 1 0 6 0 770

2009 (1) 1 0 0 0 9 0 780

2009 (2)* 1 0 0 0 1 2 784

* Incomplete half-year (based on discovery data through 2009-Aug-06 21:00 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 Atira Aten Apollo Amor PHA-KM PHA NEA-KM NEA NEO ---------- ---- ----- ---- ------ ---- ------ ---- ------ ---- ---- 2009-08-10 84 10 505 3368 2363 145 1060 784 6246 6330 2009-08-01 84 10 504 3368 2361 145 1060 784 6243 6327 2009-07-01 84 10 504 3358 2352 144 1058 780 6224 6308 2009-06-01 83 10 501 3346 2341 143 1055 779 6198 6281 2009-05-01 83 10 499 3319 2328 143 1046 778 6156 6239 2009-04-01 83 10 496 3288 2313 143 1041 775 6107 6190 2009-03-01 83 10 491 3229 2290 143 1029 775 6020 6103 2009-02-01 83 10 487 3173 2262 142 1017 772 5932 6015 2009-01-01 83 10 481 3129 2241 142 1008 770 5861 5944 2008-12-01 82 10 480 3087 2211 142 997 769 5788 5870 2008-11-01 82 10 474 3039 2189 142 989 767 5712 5794 2008-10-01 82 9 467 2978 2139 141 980 766 5593 5675 2008-09-01 82 9 464 2947 2105 141 970 764 5525 5607 2008-08-01 82 9 461 2932 2091 141 964 763 5493 5575 2008-07-01 82 9 459 2914 2080 140 955 760 5462 5544 2008-06-01 82 9 455 2903 2072 140 952 759 5439 5521 2008-05-01 81 9 451 2873 2054 140 945 758 5387 5468 2008-04-01 81 9 449 2825 2025 140 942 757 5308 5389 2008-03-01 81 8 440 2757 2000 139 933 750 5205 5286 2008-02-01 81 8 428 2697 1970 138 920 748 5103 5184 2008-01-01 81 8 426 2669 1953 138 911 748 5056 5137 2007-12-01 81 8 423 2634 1937 138 901 745 5002 5083 2007-11-01 81 8 411 2575 1902 138 891 741 4896 4977 2007-10-01 80 8 397 2526 1860 138 880 740 4791 4871 2007-09-01 80 8 390 2488 1828 137 873 739 4714 4794 2007-08-01 80 8 388 2477 1818 136 868 735 4691 4771 2007-07-01 80 8 388 2473 1811 136 867 735 4680 4760 2007-06-01 80 8 383 2452 1801 135 858 732 4644 4724 2007-05-01 80 8 382 2440 1789 135 854 730 4619 4699 2007-04-01 80 8 381 2415 1772 135 850 727 4576 4656 2007-03-01 80 7 375 2375 1749 135 843 725 4506 4586 2007-02-01 80 7 367 2342 1733 134 835 721 4449 4529 2007-01-01 80 7 359 2322 1720 134 825 720 4408 4488 2006-12-01 80 7 354 2295 1702 134 821 718 4358 4438 2006-11-01 79 6 344 2246 1678 133 809 711 4274 4353 2006-10-01 77 6 337 2216 1646 133 799 709 4205 4282 2006-09-01 77 6 330 2179 1619 132 790 705 4134 4211 2006-08-01 77 6 328 2162 1606 132 785 705 4102 4179 2006-07-01 77 6 327 2151 1589 132 783 704 4073 4150 2006-06-01 77 6 326 2140 1576 132 780 704 4048 4125 2006-05-01 77 5 325 2112 1549 132 770 700 3991 4068 2006-04-01 76 5 321 2085 1534 132 760 698 3945 4021 2006-03-01 76 5 319 2069 1515 132 759 697 3908 3984 2006-02-01 76 5 316 2034 1498 132 751 694 3853 3929 2006-01-01 76 5 312 1978 1472 131 741 689 3767 3843 2005-12-01 76 5 302 1946 1451 130 730 686 3704 3780 2005-11-01 76 5 297 1904 1425 129 720 682 3631 3707 2005-10-01 75 4 289 1848 1385 128 707 671 3526 3601 2005-09-01 75 4 286 1814 1366 128 702 668 3470 3545 2005-08-01 75 4 283 1800 1350 128 696 666 3437 3512 2005-07-01 75 4 279 1781 1338 127 689 663 3402 3477 2005-06-01 75 4 275 1766 1318 127 685 658 3363 3438 2005-05-01 74 4 274 1750 1302 125 679 655 3330 3404 2005-04-01 74 4 268 1724 1284 124 667 651 3280 3354 2005-03-01 74 4 263 1684 1259 123 657 647 3210 3284 2005-02-01 74 4 262 1660 1252 122 653 644 3178 3252 2005-01-01 74 4 258 1636 1242 122 646 640 3140 3214 2004-12-01 73 3 249 1604 1221 122 637 632 3077 3150 2004-11-01 73 3 245 1584 1215 121 628 627 3047 3120 2004-10-01 72 3 238 1556 1207 120 617 625 3004 3076 2004-09-01 71 3 230 1518 1182 120 608 624 2933 3004 2004-08-01 71 3 226 1499 1159 119 601 620 2887 2958 2004-07-01 71 3 226 1493 1154 117 598 617 2876 2947 2004-06-01 71 3 223 1463 1141 116 587 614 2830 2901 2004-05-01 71 2 218 1444 1126 116 581 611 2790 2861 2004-04-01 71 2 215 1414 1114 112 571 604 2745 2816 2004-03-01 71 2 206 1378 1096 112 564 596 2682 2753 2004-02-01 70 2 204 1363 1089 111 559 595 2658 2728 2004-01-01 70 2 202 1329 1071 109 549 591 2604 2674 2003-12-01 70 2 196 1297 1059 107 536 584 2554 2624 2003-11-01 70 2 193 1275 1046 107 528 578 2516 2586 2003-10-01 70 2 188 1248 1024 107 519 576 2462 2532 2003-09-01 70 2 185 1228 991 105 510 569 2406 2476 2003-08-01 70 2 185 1216 978 102 505 565 2381 2451 2003-07-01 69 2 184 1209 969 102 503 562 2364 2433 2003-06-01 69 2 182 1193 958 102 498 557 2335 2404 2003-05-01 67 2 180 1179 951 101 496 555 2312 2379 2003-04-01 67 2 175 1159 939 101 489 550 2275 2342 2003-03-01 67 2 170 1140 928 101 482 546 2240 2307 2003-02-01 67 1 169 1120 922 101 477 542 2212 2279 2003-01-01 67 1 167 1093 905 100 467 535 2166 2233 2002-12-01 67 1 163 1066 885 100 465 533 2115 2182 2002-11-01 67 1 160 1051 868 99 459 529 2080 2147 2002-10-01 66 1 158 1027 844 98 452 520 2030 2096 2002-09-01 64 1 155 1007 825 97 446 512 1988 2052 2002-08-01 64 1 154 991 803 95 435 508 1949 2013 2002-07-01 63 1 152 982 797 94 429 503 1932 1995 2002-06-01 63 1 148 964 789 92 421 497 1902 1965 2002-05-01 63 1 144 946 778 91 412 486 1869 1932 2002-04-01 63 1 142 928 766 91 405 484 1837 1900 2002-03-01 62 1 136 901 753 90 395 480 1791 1853 2002-02-01 62 1 131 878 737 89 386 470 1747 1809 2002-01-01 62 1 124 843 715 89 373 461 1683 1745 2001-12-01 62 1 121 806 697 85 359 452 1625 1687 2001-11-01 60 1 120 779 681 84 351 448 1581 1641 2001-10-01 60 1 114 753 658 83 342 444 1526 1586 2001-09-01 60 1 110 724 624 82 331 433 1459 1519 2001-08-01 59 1 109 702 604 82 325 431 1416 1475 2001-07-01 58 1 108 697 591 82 324 429 1397 1455 2001-06-01 57 1 108 687 580 80 321 422 1376 1433 2001-05-01 56 1 107 675 569 78 314 414 1352 1408 2001-04-01 56 1 105 663 560 77 306 411 1329 1385 2001-03-01 56 1 101 648 546 75 297 403 1296 1352 2001-02-01 56 1 98 637 535 74 294 398 1271 1327 2001-01-01 56 1 94 622 526 74 291 394 1243 1299 2000-12-01 56 1 93 608 514 73 285 387 1216 1272 2000-11-01 56 1 90 584 497 72 282 378 1172 1228 2000-10-01 56 1 87 574 483 72 278 370 1145 1201 2000-09-01 56 1 81 556 457 71 272 361 1095 1151 2000-08-01 56 1 79 538 441 69 263 352 1059 1115 2000-07-01 56 1 77 533 431 67 260 342 1042 1098 2000-06-01 56 1 76 528 425 66 256 339 1030 1086 2000-05-01 56 1 76 515 411 66 251 334 1003 1059 2000-04-01 55 1 73 500 398 65 245 327 972 1027 2000-03-01 55 1 64 484 387 63 233 316 936 991 2000-02-01 55 1 62 467 376 62 222 309 906 961 2000-01-01 55 1 57 453 369 62 215 304 880 935 1999-12-01 54 1 56 443 360 60 207 297 860 914 1999-11-01 54 1 54 430 346 60 203 288 831 885 1999-10-01 54 1 54 414 332 59 198 283 801 855 1999-09-01 52 1 54 397 317 58 192 279 769 821 1999-08-01 52 1 54 397 315 58 192 279 767 819 1999-07-01 52 1 54 392 310 57 190 275 757 809 1999-06-01 52 1 51 385 300 56 185 272 737 789 1999-05-01 52 1 49 373 294 52 177 262 717 769 1999-04-01 52 1 48 360 287 51 173 255 696 748 1999-03-01 52 1 47 350 282 51 172 254 680 732 1999-02-01 52 1 47 340 277 51 169 251 665 717 1999-01-01 52 1 45 335 271 51 166 248 652 704 1998-12-01 52 1 41 325 262 51 162 240 629 681 1998-11-01 52 1 38 308 254 49 154 235 601 653 1998-10-01 52 1 36 303 248 49 152 231 588 640 1998-09-01 52 1 29 290 235 48 140 225 555 607 1998-08-01 52 1 29 280 224 46 133 219 534 586 1998-07-01 52 1 29 277 221 44 129 216 528 580 1998-06-01 52 1 29 271 214 43 127 212 515 567 1998-05-01 52 1 29 262 208 43 124 208 500 552 1998-04-01 52 1 27 254 199 43 117 207 481 533 1998-03-01 52 1 27 242 191 43 112 203 461 513 1998-02-01 52 0 26 238 191 42 110 202 455 507 1998-01-01 52 0 26 233 188 42 108 199 447 499 1997-01-01 52 0 22 204 168 40 97 187 394 446 1996-01-01 52 0 20 177 152 38 86 181 349 401 1995-01-01 52 0 19 163 135 37 83 171 317 369 1994-01-01 50 0 15 140 116 33 70 154 271 321 1993-01-01 50 0 13 117 100 31 64 140 230 280 1992-01-01 50 0 11 103 85 29 61 123 199 249 1991-01-01 48 0 9 76 74 24 49 107 159 207 1990-01-01 48 0 8 63 63 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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