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)	182	64	15	20	0	4	1682
2002 (1)	158	54	16	14	1	6	1931
2002 (2)	128	88	6	7	0	5	2165
2003 (1)	102	30	24	34	0	8	2363
2003 (2)	133	38	33	20	8	8	2603
2004 (1)	167	19	41	14	25	6	2875
2004 (2)	137	7	29	25	60	6	3139
2005 (1)	78	8	28	22	116	10	3401
2005 (2)	59	30	54	19	193	10	3766
2006 (1)	44	4	45	13	197	3	4072
2006 (2)	52	18	54	6	200	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	284	5	5462
2008 (2)	67	0	43	0	280	11	5863
2009 (1)*	0	0	2	0	10	0	5875

* Incomplete half-year (based on discovery data through 2009-Jan-09 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 2 175

1995 (2) 0 0 4 0 0 1 180

1996 (1) 0 2 2 0 0 0 184

1996 (2) 0 2 0 0 0 0 186

1997 (1) 0 1 2 0 0 1 190

1997 (2) 2 3 1 0 0 2 198

1998 (1) 8 4 2 1 0 1 214

1998 (2) 23 2 1 3 0 3 246

1999 (1) 17 0 2 5 3 0 273

1999 (2) 24 0 0 1 2 2 302

2000 (1) 30 2 0 1 4 1 340

2000 (2) 39 2 3 3 0 4 391

2001 (1) 24 8 0 3 0 0 426

2001 (2) 22 5 0 4 0 1 458

2002 (1) 30 4 2 3 0 1 498

2002 (2) 20 10 0 1 0 1 530

2003 (1) 15 3 1 6 0 1 556

2003 (2) 17 5 1 4 1 1 585

2004 (1) 14 5 1 2 2 1 610

2004 (2) 8 1 0 1 13 0 633

2005 (1) 10 0 2 1 9 1 656

2005 (2) 6 5 4 0 9 1 681

2006 (1) 3 0 2 1 9 0 696

2006 (2) 1 0 3 0 12 0 712

2007 (1) 2 0 3 0 9 1 727

2007 (2) 5 0 1 0 7 0 740

2008 (1) 2 0 1 0 9 0 752

2008 (2) 3 0 1 0 6 0 762

2009 (1)* 0 0 1 0 0 0 763

* Incomplete half-year (based on discovery data through 2009-Jan-09 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 ---------- ---- ---- ------ ---- ------ ---- ------ ---- ---- 2009-01-07 82 482 3135 2248 141 1010 763 5875 5957 2009-01-01 82 481 3130 2242 141 1007 762 5863 5945 2008-12-01 82 480 3088 2213 141 997 761 5791 5873 2008-11-01 82 474 3040 2190 141 988 759 5714 5796 2008-10-01 82 467 2979 2138 140 979 757 5593 5675 2008-09-01 82 464 2948 2104 140 969 756 5525 5607 2008-08-01 82 461 2933 2090 140 963 755 5493 5575 2008-07-01 82 459 2915 2079 139 954 752 5462 5544 2008-06-01 82 455 2904 2071 139 951 751 5439 5521 2008-05-01 81 451 2873 2053 139 943 750 5386 5467 2008-04-01 81 449 2825 2024 139 940 749 5307 5388 2008-03-01 81 440 2757 1999 138 931 742 5204 5285 2008-02-01 81 428 2697 1969 137 918 740 5102 5183 2008-01-01 81 426 2669 1952 137 909 740 5055 5136 2007-12-01 81 423 2634 1936 137 900 737 5001 5082 2007-11-01 81 411 2575 1901 137 890 733 4895 4976 2007-10-01 80 397 2526 1859 137 879 732 4790 4870 2007-09-01 80 390 2488 1827 136 872 731 4713 4793 2007-08-01 80 388 2477 1817 135 867 727 4690 4770 2007-07-01 80 388 2473 1810 135 866 727 4679 4759 2007-06-01 80 383 2452 1800 134 857 724 4643 4723 2007-05-01 80 382 2440 1788 134 853 722 4618 4698 2007-04-01 80 381 2415 1771 134 849 719 4575 4655 2007-03-01 80 375 2375 1748 134 842 717 4505 4585 2007-02-01 80 367 2342 1732 133 834 713 4448 4528 2007-01-01 80 359 2322 1719 133 825 712 4407 4487 2006-12-01 80 354 2295 1701 133 821 710 4357 4437 2006-11-01 79 344 2246 1677 132 809 703 4273 4352 2006-10-01 77 337 2216 1645 132 799 701 4204 4281 2006-09-01 77 330 2179 1618 131 790 697 4133 4210 2006-08-01 77 328 2162 1605 131 785 697 4101 4178 2006-07-01 77 327 2151 1588 131 783 696 4072 4149 2006-06-01 77 326 2140 1575 131 780 696 4047 4124 2006-05-01 77 325 2112 1548 131 770 692 3990 4067 2006-04-01 76 321 2085 1533 131 760 690 3944 4020 2006-03-01 76 319 2069 1514 131 759 689 3907 3983 2006-02-01 76 316 2034 1497 131 751 686 3852 3928 2006-01-01 76 312 1977 1472 130 741 681 3766 3842 2005-12-01 76 302 1945 1451 129 730 678 3703 3779 2005-11-01 76 297 1903 1425 128 720 674 3630 3706 2005-10-01 75 289 1847 1385 127 707 664 3525 3600 2005-09-01 75 286 1813 1366 127 702 661 3469 3544 2005-08-01 75 283 1799 1350 127 696 659 3436 3511 2005-07-01 75 279 1780 1338 126 688 656 3401 3476 2005-06-01 75 275 1765 1318 126 684 651 3362 3437 2005-05-01 74 274 1749 1302 124 678 648 3329 3403 2005-04-01 74 268 1723 1284 122 665 644 3279 3353 2005-03-01 74 263 1683 1259 121 655 640 3209 3283 2005-02-01 74 262 1659 1252 120 651 637 3177 3251 2005-01-01 74 258 1635 1242 120 644 633 3139 3213 2004-12-01 73 249 1603 1221 120 635 625 3076 3149 2004-11-01 73 245 1583 1215 119 626 620 3046 3119 2004-10-01 72 238 1555 1207 118 615 618 3003 3075 2004-09-01 71 230 1517 1182 118 606 617 2932 3003 2004-08-01 71 226 1498 1159 117 599 613 2886 2957 2004-07-01 71 226 1492 1154 115 596 610 2875 2946 2004-06-01 71 223 1462 1141 114 585 607 2829 2900 2004-05-01 71 218 1443 1126 114 579 604 2789 2860 2004-04-01 71 215 1413 1114 110 569 597 2744 2815 2004-03-01 71 206 1377 1096 110 562 590 2681 2752 2004-02-01 70 204 1362 1089 109 557 589 2657 2727 2004-01-01 70 202 1328 1071 107 547 585 2603 2673 2003-12-01 70 196 1296 1059 105 534 578 2553 2623 2003-11-01 70 193 1274 1046 105 526 572 2515 2585 2003-10-01 70 188 1247 1024 105 517 570 2461 2531 2003-09-01 70 185 1227 991 103 508 563 2405 2475 2003-08-01 70 185 1215 978 100 503 559 2380 2450 2003-07-01 69 184 1208 969 100 501 556 2363 2432 2003-06-01 69 182 1192 958 100 496 551 2334 2403 2003-05-01 67 180 1178 951 99 494 549 2311 2378 2003-04-01 67 175 1158 939 99 487 544 2274 2341 2003-03-01 67 170 1139 928 99 480 540 2239 2306 2003-02-01 67 169 1119 922 99 475 536 2211 2278 2003-01-01 67 167 1092 905 98 465 530 2165 2232 2002-12-01 67 163 1065 885 98 463 528 2114 2181 2002-11-01 67 160 1050 868 97 457 524 2079 2146 2002-10-01 66 158 1026 844 96 451 515 2029 2095 2002-09-01 64 155 1006 825 95 445 507 1987 2051 2002-08-01 64 154 990 803 93 434 503 1948 2012 2002-07-01 63 152 981 797 92 428 498 1931 1994 2002-06-01 63 148 963 789 90 420 492 1901 1964 2002-05-01 63 144 945 778 89 411 482 1868 1931 2002-04-01 63 142 927 766 89 404 480 1836 1899 2002-03-01 62 136 900 753 88 394 477 1790 1852 2002-02-01 62 131 877 737 87 385 467 1746 1808 2002-01-01 62 124 842 715 87 372 458 1682 1744 2001-12-01 62 121 805 697 83 358 449 1624 1686 2001-11-01 60 120 778 681 82 350 445 1580 1640 2001-10-01 60 114 752 658 81 341 441 1525 1585 2001-09-01 60 110 723 625 80 330 430 1459 1519 2001-08-01 59 109 701 605 80 324 428 1416 1475 2001-07-01 58 108 696 592 80 323 426 1397 1455 2001-06-01 57 108 686 581 78 320 419 1376 1433 2001-05-01 56 107 674 570 76 313 411 1352 1408 2001-04-01 56 105 662 561 75 305 408 1329 1385 2001-03-01 56 101 647 547 73 296 400 1296 1352 2001-02-01 56 98 636 536 72 293 395 1271 1327 2001-01-01 56 94 621 527 72 290 391 1243 1299 2000-12-01 56 93 607 515 71 284 384 1216 1272 2000-11-01 56 90 583 498 70 281 375 1172 1228 2000-10-01 56 87 573 484 70 277 367 1145 1201 2000-09-01 56 81 555 458 69 271 358 1095 1151 2000-08-01 56 79 537 442 67 262 349 1059 1115 2000-07-01 56 77 532 432 65 259 340 1042 1098 2000-06-01 56 76 527 426 64 255 337 1030 1086 2000-05-01 56 76 514 412 64 250 332 1003 1059 2000-04-01 55 73 499 399 63 244 325 972 1027 2000-03-01 55 64 483 388 61 232 314 936 991 2000-02-01 55 62 466 377 60 221 307 906 961 2000-01-01 55 57 453 369 60 214 302 880 935 1999-12-01 54 56 443 360 58 206 295 860 914 1999-11-01 54 54 430 346 58 202 286 831 885 1999-10-01 54 54 414 332 57 197 281 801 855 1999-09-01 52 54 397 317 56 191 277 769 821 1999-08-01 52 54 397 315 56 191 277 767 819 1999-07-01 52 54 392 310 55 189 273 757 809 1999-06-01 52 51 385 300 54 184 270 737 789 1999-05-01 52 49 373 294 51 177 260 717 769 1999-04-01 52 48 360 287 50 173 253 696 748 1999-03-01 52 47 350 282 50 172 252 680 732 1999-02-01 52 47 340 277 50 169 249 665 717 1999-01-01 52 45 335 271 50 166 246 652 704 1998-12-01 52 41 325 262 50 162 238 629 681 1998-11-01 52 38 308 254 48 154 233 601 653 1998-10-01 52 36 303 248 48 152 229 588 640 1998-09-01 52 29 290 235 47 140 223 555 607 1998-08-01 52 29 280 224 45 133 217 534 586 1998-07-01 52 29 277 221 43 129 214 528 580 1998-06-01 52 29 271 214 42 127 210 515 567 1998-05-01 52 29 262 208 42 124 206 500 552 1998-04-01 52 27 254 199 42 117 205 481 533 1998-03-01 52 27 242 191 42 112 201 461 513 1998-02-01 52 26 238 191 42 110 201 455 507 1998-01-01 52 26 233 188 42 108 198 447 499 1997-01-01 52 22 204 168 40 97 186 394 446 1996-01-01 52 20 177 152 38 86 180 349 401 1995-01-01 52 19 163 135 37 83 170 317 369 1994-01-01 50 15 140 116 33 70 153 271 321 1993-01-01 50 13 117 100 31 64 139 230 280 1992-01-01 50 11 103 85 29 61 122 199 249 1991-01-01 48 9 76 74 24 49 106 159 207 1990-01-01 48 8 63 63 20 42 90 134 182 1980-01-01 44 3 27 23 12 17 45 53 97 1970-01-01 42 0 13 14 8 10 24 27 69 1960-01-01 41 0 10 10 7 8 18 20 61 1950-01-01 41 0 7 6 4 5 12 13 54 1940-01-01 36 0 3 6 2 3 8 9 45 1930-01-01 34 0 0 5 0 0 5 5 39 1920-01-01 32 0 0 3 0 0 3 3 35 1910-01-01 30 0 0 1 0 0 1 1 31 1900-01-01 28 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.

Data compiled by Alan Chamberlin.

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