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	283	5	5461
2008 (2)	67	0	43	0	278	11	5860
2009 (1)*	48	0	29	0	215	13	6165

* Incomplete half-year (based on discovery data through 2009-May-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 2 215

1998 (2) 23 2 1 3 0 3 247

1999 (1) 17 0 2 5 3 0 274

1999 (2) 24 0 0 1 2 2 303

2000 (1) 30 2 0 1 4 1 341

2000 (2) 39 2 3 4 0 4 393

2001 (1) 24 8 0 3 0 0 428

2001 (2) 22 5 0 4 0 1 460

2002 (1) 32 4 2 3 0 1 502

2002 (2) 20 10 0 1 0 1 534

2003 (1) 15 3 1 6 0 1 560

2003 (2) 17 5 1 4 1 1 589

2004 (1) 15 5 1 2 2 1 615

2004 (2) 8 1 0 1 13 0 638

2005 (1) 10 0 2 1 9 1 661

2005 (2) 6 5 5 0 9 1 687

2006 (1) 3 0 2 1 9 0 702

2006 (2) 1 0 3 0 12 0 718

2007 (1) 2 0 3 0 9 1 733

2007 (2) 5 0 1 0 7 0 746

2008 (1) 2 0 1 0 9 0 758

2008 (2) 3 0 1 0 6 0 768

2009 (1)* 1 0 0 0 7 0 776

* Incomplete half-year (based on discovery data through 2009-May-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 ---------- ---- ---- ------ ---- ------ ---- ------ ---- ---- 2009-05-05 83 500 3326 2329 143 1047 776 6165 6248 2009-05-01 83 500 3319 2327 143 1046 776 6156 6239 2009-04-01 83 497 3288 2312 143 1041 773 6107 6190 2009-03-01 83 491 3229 2289 143 1029 773 6019 6102 2009-02-01 83 487 3173 2261 142 1017 770 5931 6014 2009-01-01 83 481 3129 2240 142 1008 768 5860 5943 2008-12-01 82 480 3087 2210 142 997 767 5787 5869 2008-11-01 82 474 3039 2188 142 989 765 5711 5793 2008-10-01 82 467 2978 2138 141 980 764 5592 5674 2008-09-01 82 464 2947 2104 141 970 762 5524 5606 2008-08-01 82 461 2932 2090 141 964 761 5492 5574 2008-07-01 82 459 2914 2079 140 955 758 5461 5543 2008-06-01 82 455 2903 2071 140 952 757 5438 5520 2008-05-01 81 451 2873 2053 140 945 756 5386 5467 2008-04-01 81 449 2825 2024 140 942 755 5307 5388 2008-03-01 81 440 2757 1999 139 933 748 5204 5285 2008-02-01 81 428 2697 1969 138 920 746 5102 5183 2008-01-01 81 426 2669 1952 138 911 746 5055 5136 2007-12-01 81 423 2634 1936 138 901 743 5001 5082 2007-11-01 81 411 2575 1901 138 891 739 4895 4976 2007-10-01 80 397 2526 1859 138 880 738 4790 4870 2007-09-01 80 390 2488 1827 137 873 737 4713 4793 2007-08-01 80 388 2477 1817 136 868 733 4690 4770 2007-07-01 80 388 2473 1810 136 867 733 4679 4759 2007-06-01 80 383 2452 1800 135 858 730 4643 4723 2007-05-01 80 382 2440 1788 135 854 728 4618 4698 2007-04-01 80 381 2415 1771 135 850 725 4575 4655 2007-03-01 80 375 2375 1748 135 843 723 4505 4585 2007-02-01 80 367 2342 1732 134 835 719 4448 4528 2007-01-01 80 359 2322 1719 134 825 718 4407 4487 2006-12-01 80 354 2295 1701 134 821 716 4357 4437 2006-11-01 79 344 2246 1677 133 809 709 4273 4352 2006-10-01 77 337 2216 1645 133 799 707 4204 4281 2006-09-01 77 330 2179 1618 132 790 703 4133 4210 2006-08-01 77 328 2162 1605 132 785 703 4101 4178 2006-07-01 77 327 2151 1588 132 783 702 4072 4149 2006-06-01 77 326 2140 1575 132 780 702 4047 4124 2006-05-01 77 325 2112 1548 132 770 698 3990 4067 2006-04-01 76 321 2085 1533 132 760 696 3944 4020 2006-03-01 76 319 2069 1514 132 759 695 3907 3983 2006-02-01 76 316 2034 1497 132 751 692 3852 3928 2006-01-01 76 312 1978 1471 131 741 687 3766 3842 2005-12-01 76 302 1946 1450 130 730 684 3703 3779 2005-11-01 76 297 1904 1424 129 720 680 3630 3706 2005-10-01 75 289 1848 1384 128 707 669 3525 3600 2005-09-01 75 286 1814 1365 128 702 666 3469 3544 2005-08-01 75 283 1800 1349 128 696 664 3436 3511 2005-07-01 75 279 1781 1337 127 689 661 3401 3476 2005-06-01 75 275 1766 1317 127 685 656 3362 3437 2005-05-01 74 274 1750 1301 125 679 653 3329 3403 2005-04-01 74 268 1724 1283 124 667 649 3279 3353 2005-03-01 74 263 1684 1258 123 657 645 3209 3283 2005-02-01 74 262 1660 1251 122 653 642 3177 3251 2005-01-01 74 258 1636 1241 122 646 638 3139 3213 2004-12-01 73 249 1604 1220 122 637 630 3076 3149 2004-11-01 73 245 1584 1214 121 628 625 3046 3119 2004-10-01 72 238 1556 1206 120 617 623 3003 3075 2004-09-01 71 230 1518 1181 120 608 622 2932 3003 2004-08-01 71 226 1499 1158 119 601 618 2886 2957 2004-07-01 71 226 1493 1153 117 598 615 2875 2946 2004-06-01 71 223 1463 1140 116 587 612 2829 2900 2004-05-01 71 218 1444 1125 116 581 609 2789 2860 2004-04-01 71 215 1414 1113 112 571 602 2744 2815 2004-03-01 71 206 1378 1095 112 564 594 2681 2752 2004-02-01 70 204 1363 1088 111 559 593 2657 2727 2004-01-01 70 202 1329 1070 109 549 589 2603 2673 2003-12-01 70 196 1297 1058 107 536 582 2553 2623 2003-11-01 70 193 1275 1045 107 528 576 2515 2585 2003-10-01 70 188 1248 1023 107 519 574 2461 2531 2003-09-01 70 185 1228 990 105 510 567 2405 2475 2003-08-01 70 185 1216 977 102 505 563 2380 2450 2003-07-01 69 184 1209 968 102 503 560 2363 2432 2003-06-01 69 182 1193 957 102 498 555 2334 2403 2003-05-01 67 180 1179 950 101 496 553 2311 2378 2003-04-01 67 175 1159 938 101 489 548 2274 2341 2003-03-01 67 170 1140 927 101 482 544 2239 2306 2003-02-01 67 169 1120 921 101 477 540 2211 2278 2003-01-01 67 167 1093 904 100 467 534 2165 2232 2002-12-01 67 163 1066 884 100 465 532 2114 2181 2002-11-01 67 160 1051 867 99 459 528 2079 2146 2002-10-01 66 158 1027 843 98 452 519 2029 2095 2002-09-01 64 155 1007 824 97 446 511 1987 2051 2002-08-01 64 154 991 802 95 435 507 1948 2012 2002-07-01 63 152 982 796 94 429 502 1931 1994 2002-06-01 63 148 964 788 92 421 496 1901 1964 2002-05-01 63 144 946 777 91 412 485 1868 1931 2002-04-01 63 142 928 765 91 405 483 1836 1899 2002-03-01 62 136 901 752 90 395 479 1790 1852 2002-02-01 62 131 878 736 89 386 469 1746 1808 2002-01-01 62 124 843 714 89 373 460 1682 1744 2001-12-01 62 121 806 696 85 359 451 1624 1686 2001-11-01 60 120 779 680 84 351 447 1580 1640 2001-10-01 60 114 753 657 83 342 443 1525 1585 2001-09-01 60 110 724 624 82 331 432 1459 1519 2001-08-01 59 109 702 604 82 325 430 1416 1475 2001-07-01 58 108 697 591 82 324 428 1397 1455 2001-06-01 57 108 687 580 80 321 421 1376 1433 2001-05-01 56 107 675 569 78 314 413 1352 1408 2001-04-01 56 105 663 560 77 306 410 1329 1385 2001-03-01 56 101 648 546 75 297 402 1296 1352 2001-02-01 56 98 637 535 74 294 397 1271 1327 2001-01-01 56 94 622 526 74 291 393 1243 1299 2000-12-01 56 93 608 514 73 285 386 1216 1272 2000-11-01 56 90 584 497 72 282 377 1172 1228 2000-10-01 56 87 574 483 72 278 369 1145 1201 2000-09-01 56 81 556 457 71 272 360 1095 1151 2000-08-01 56 79 538 441 69 263 351 1059 1115 2000-07-01 56 77 533 431 67 260 341 1042 1098 2000-06-01 56 76 528 425 66 256 338 1030 1086 2000-05-01 56 76 515 411 66 251 333 1003 1059 2000-04-01 55 73 500 398 65 245 326 972 1027 2000-03-01 55 64 484 387 63 233 315 936 991 2000-02-01 55 62 467 376 62 222 308 906 961 2000-01-01 55 57 453 369 62 215 303 880 935 1999-12-01 54 56 443 360 60 207 296 860 914 1999-11-01 54 54 430 346 60 203 287 831 885 1999-10-01 54 54 414 332 59 198 282 801 855 1999-09-01 52 54 397 317 58 192 278 769 821 1999-08-01 52 54 397 315 58 192 278 767 819 1999-07-01 52 54 392 310 57 190 274 757 809 1999-06-01 52 51 385 300 56 185 271 737 789 1999-05-01 52 49 373 294 52 177 261 717 769 1999-04-01 52 48 360 287 51 173 254 696 748 1999-03-01 52 47 350 282 51 172 253 680 732 1999-02-01 52 47 340 277 51 169 250 665 717 1999-01-01 52 45 335 271 51 166 247 652 704 1998-12-01 52 41 325 262 51 162 239 629 681 1998-11-01 52 38 308 254 49 154 234 601 653 1998-10-01 52 36 303 248 49 152 230 588 640 1998-09-01 52 29 290 235 48 140 224 555 607 1998-08-01 52 29 280 224 46 133 218 534 586 1998-07-01 52 29 277 221 44 129 215 528 580 1998-06-01 52 29 271 214 43 127 211 515 567 1998-05-01 52 29 262 208 43 124 207 500 552 1998-04-01 52 27 254 199 43 117 206 481 533 1998-03-01 52 27 242 191 43 112 202 461 513 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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