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)	184	64	15	20	0	4	1684
2002 (1)	158	55	16	14	1	6	1934
2002 (2)	128	89	6	7	0	5	2169
2003 (1)	102	30	24	34	0	9	2368
2003 (2)	133	38	33	21	8	8	2609
2004 (1)	167	19	41	14	24	6	2880
2004 (2)	137	7	29	25	60	6	3144
2005 (1)	78	8	28	22	116	10	3406
2005 (2)	59	30	54	19	193	10	3771
2006 (1)	44	4	45	13	197	3	4077
2006 (2)	52	18	54	6	200	5	4412
2007 (1)	38	4	20	7	200	3	4684
2007 (2)	74	0	25	5	266	7	5061
2008 (1)	74	0	43	1	282	5	5466
2008 (2)	67	0	43	0	278	11	5865
2009 (1)	50	0	32	0	263	18	6228
2009 (2)	58	0	31	0	314	17	6648
2010 (1)	29	0	21	0	258	98	7054
2010 (2)*	19	0	2	0	14	25	7114

* Incomplete half-year (based on discovery data through 2010-Aug-23 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 2 178

1995 (2) 0 0 4 0 0 1 183

1996 (1) 0 2 2 0 0 0 187

1996 (2) 0 2 0 0 0 0 189

1997 (1) 0 1 2 0 0 1 193

1997 (2) 2 3 1 0 0 2 201

1998 (1) 8 4 2 1 0 2 218

1998 (2) 24 2 1 3 0 3 251

1999 (1) 17 0 2 5 4 0 279

1999 (2) 24 0 0 1 3 2 309

2000 (1) 30 2 0 1 4 1 347

2000 (2) 39 2 3 5 0 4 400

2001 (1) 24 8 0 3 0 0 435

2001 (2) 23 4 0 4 0 1 467

2002 (1) 32 4 2 3 0 1 509

2002 (2) 20 10 0 1 0 1 541

2003 (1) 16 3 1 6 0 2 569

2003 (2) 17 5 1 4 1 1 598

2004 (1) 16 5 1 2 3 1 626

2004 (2) 8 1 0 1 13 0 649

2005 (1) 10 0 2 1 9 1 672

2005 (2) 6 5 5 0 10 1 699

2006 (1) 3 0 2 1 9 0 714

2006 (2) 1 0 3 0 12 0 730

2007 (1) 2 0 3 0 10 1 746

2007 (2) 6 0 1 0 7 0 760

2008 (1) 2 0 1 0 8 0 771

2008 (2) 3 0 1 0 6 0 781

2009 (1) 1 0 1 0 8 0 791

2009 (2) 6 0 0 0 7 2 806

2010 (1) 0 0 0 0 4 3 813

2010 (2)* 0 0 0 0 0 2 815

* Incomplete half-year (based on discovery data through 2010-Aug-23 06:05 local)

Data compiled by Alan Chamberlin.

NUMBER OF NEOS

NASA's current search program is designed to discover 90% of the NEO population. A separate table containing WISE discoveries for NEAs and comets is available.

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 ---------- ---- ----- ---- ------ ---- ------ ---- ------ ---- ---- 2010-08-20 85 10 582 3862 2660 149 1137 815 7114 7199 2010-08-01 85 10 579 3851 2651 149 1134 815 7091 7176 2010-07-01 85 10 574 3830 2640 149 1132 813 7054 7139 2010-06-01 85 10 568 3798 2621 149 1125 813 6997 7082 2010-05-01 84 10 560 3755 2600 148 1113 811 6925 7009 2010-04-01 84 10 552 3708 2583 148 1108 811 6853 6937 2010-03-01 84 10 544 3671 2557 148 1099 811 6782 6866 2010-02-01 84 10 540 3618 2531 147 1088 809 6699 6783 2010-01-01 84 10 535 3591 2512 146 1084 806 6648 6732 2009-12-01 84 10 531 3570 2502 146 1079 804 6613 6697 2009-11-01 84 10 520 3494 2474 146 1071 801 6498 6582 2009-10-01 84 10 511 3439 2441 146 1067 799 6401 6485 2009-09-01 84 10 506 3386 2394 146 1057 797 6296 6380 2009-08-01 84 10 504 3366 2367 146 1055 795 6247 6331 2009-07-01 84 10 504 3356 2358 145 1053 791 6228 6312 2009-06-01 83 10 501 3344 2347 144 1050 790 6202 6285 2009-05-01 83 10 499 3317 2334 144 1041 788 6160 6243 2009-04-01 83 10 496 3286 2319 144 1037 786 6111 6194 2009-03-01 83 10 491 3226 2297 144 1025 786 6024 6107 2009-02-01 83 10 487 3170 2269 143 1013 783 5936 6019 2009-01-01 83 10 481 3126 2248 143 1004 781 5865 5948 2008-12-01 82 10 480 3084 2218 143 994 780 5792 5874 2008-11-01 82 10 474 3036 2196 143 986 778 5716 5798 2008-10-01 82 9 467 2975 2146 142 976 777 5597 5679 2008-09-01 81 9 464 2944 2112 142 966 775 5529 5610 2008-08-01 81 9 461 2929 2098 142 960 774 5497 5578 2008-07-01 81 9 459 2911 2087 141 951 771 5466 5547 2008-06-01 81 9 455 2900 2079 141 948 770 5443 5524 2008-05-01 81 9 451 2870 2062 141 941 770 5392 5473 2008-04-01 81 9 449 2822 2033 141 938 769 5313 5394 2008-03-01 81 8 440 2754 2008 140 928 762 5210 5291 2008-02-01 81 8 428 2695 1977 139 914 760 5108 5189 2008-01-01 81 8 426 2667 1960 139 905 760 5061 5142 2007-12-01 81 8 423 2632 1943 139 896 756 5006 5087 2007-11-01 81 8 411 2573 1908 139 886 752 4900 4981 2007-10-01 80 8 397 2524 1866 139 875 751 4795 4875 2007-09-01 80 8 390 2486 1834 138 868 750 4718 4798 2007-08-01 80 8 388 2475 1824 137 863 746 4695 4775 2007-07-01 80 8 388 2471 1817 137 862 746 4684 4764 2007-06-01 80 8 383 2450 1807 136 853 743 4648 4728 2007-05-01 80 8 382 2438 1795 136 849 741 4623 4703 2007-04-01 80 8 381 2413 1778 136 845 737 4580 4660 2007-03-01 80 7 375 2373 1755 136 838 735 4510 4590 2007-02-01 80 7 367 2340 1739 135 830 731 4453 4533 2007-01-01 80 7 359 2320 1726 135 821 730 4412 4492 2006-12-01 79 7 354 2293 1708 135 818 728 4362 4441 2006-11-01 79 6 344 2244 1684 134 806 721 4278 4357 2006-10-01 77 6 337 2214 1652 134 796 719 4209 4286 2006-09-01 77 6 330 2177 1625 133 787 715 4138 4215 2006-08-01 77 6 328 2160 1612 133 782 715 4106 4183 2006-07-01 77 6 327 2149 1595 133 780 714 4077 4154 2006-06-01 77 6 326 2138 1582 133 777 714 4052 4129 2006-05-01 77 5 325 2110 1555 133 767 710 3995 4072 2006-04-01 76 5 321 2083 1540 133 757 708 3949 4025 2006-03-01 76 5 319 2067 1521 133 756 707 3912 3988 2006-02-01 76 5 316 2032 1504 133 748 704 3857 3933 2006-01-01 76 5 312 1977 1477 132 739 699 3771 3847 2005-12-01 76 5 302 1945 1456 131 728 696 3708 3784 2005-11-01 76 5 297 1903 1430 130 718 691 3635 3711 2005-10-01 75 4 289 1847 1390 129 706 680 3530 3605 2005-09-01 75 4 286 1813 1371 129 701 677 3474 3549 2005-08-01 75 4 283 1799 1355 129 695 675 3441 3516 2005-07-01 75 4 279 1780 1343 128 688 672 3406 3481 2005-06-01 75 4 275 1765 1323 128 684 667 3367 3442 2005-05-01 74 4 274 1749 1307 126 678 664 3334 3408 2005-04-01 74 4 268 1723 1289 124 665 660 3284 3358 2005-03-01 74 4 263 1683 1264 123 655 656 3214 3288 2005-02-01 74 4 262 1659 1257 122 651 653 3182 3256 2005-01-01 74 4 258 1635 1247 122 644 649 3144 3218 2004-12-01 73 3 249 1603 1226 122 635 641 3081 3154 2004-11-01 73 3 245 1583 1220 121 626 636 3051 3124 2004-10-01 72 3 238 1555 1212 120 615 634 3008 3080 2004-09-01 71 3 230 1517 1187 120 607 633 2937 3008 2004-08-01 71 3 226 1498 1164 119 600 629 2891 2962 2004-07-01 71 3 226 1492 1159 117 597 626 2880 2951 2004-06-01 71 3 223 1462 1146 116 586 623 2834 2905 2004-05-01 71 2 218 1443 1131 116 580 619 2794 2865 2004-04-01 71 2 215 1413 1119 112 570 612 2749 2820 2004-03-01 71 2 206 1377 1101 112 563 603 2686 2757 2004-02-01 70 2 204 1362 1095 111 558 602 2663 2733 2004-01-01 70 2 202 1328 1077 109 548 598 2609 2679 2003-12-01 70 2 196 1296 1065 107 536 591 2559 2629 2003-11-01 70 2 193 1274 1052 107 528 585 2521 2591 2003-10-01 70 2 188 1247 1030 107 520 583 2467 2537 2003-09-01 70 2 185 1227 996 105 511 576 2410 2480 2003-08-01 70 2 185 1215 983 102 506 572 2385 2455 2003-07-01 69 2 184 1208 974 102 504 569 2368 2437 2003-06-01 69 2 182 1192 962 102 499 563 2338 2407 2003-05-01 67 2 180 1178 955 101 497 561 2315 2382 2003-04-01 67 2 175 1158 943 101 490 556 2278 2345 2003-03-01 67 2 170 1139 932 101 483 552 2243 2310 2003-02-01 67 1 169 1119 926 101 478 548 2215 2282 2003-01-01 67 1 167 1092 909 100 468 541 2169 2236 2002-12-01 67 1 163 1065 889 100 466 539 2118 2185 2002-11-01 67 1 160 1050 872 99 460 535 2083 2150 2002-10-01 66 1 158 1026 848 98 454 526 2033 2099 2002-09-01 64 1 155 1006 829 97 448 518 1991 2055 2002-08-01 64 1 154 990 807 95 437 514 1952 2016 2002-07-01 63 1 152 980 801 94 430 509 1934 1997 2002-06-01 63 1 148 962 793 92 421 503 1904 1967 2002-05-01 63 1 144 944 782 91 412 492 1871 1934 2002-04-01 63 1 142 926 769 91 405 490 1838 1901 2002-03-01 62 1 136 899 756 90 395 486 1792 1854 2002-02-01 62 1 131 876 740 89 386 476 1748 1810 2002-01-01 62 1 124 841 718 89 373 467 1684 1746 2001-12-01 62 1 121 805 699 85 359 458 1626 1688 2001-11-01 60 1 120 778 683 84 351 454 1582 1642 2001-10-01 60 1 114 752 660 83 341 450 1527 1587 2001-09-01 60 1 110 723 625 82 330 438 1459 1519 2001-08-01 59 1 109 701 605 82 324 436 1416 1475 2001-07-01 58 1 108 696 592 82 323 435 1397 1455 2001-06-01 57 1 108 686 581 80 320 428 1376 1433 2001-05-01 56 1 107 674 570 78 313 420 1352 1408 2001-04-01 56 1 105 662 561 77 305 417 1329 1385 2001-03-01 56 1 101 647 547 75 296 409 1296 1352 2001-02-01 56 1 98 636 536 74 293 404 1271 1327 2001-01-01 56 1 94 621 527 74 290 400 1243 1299 2000-12-01 56 1 93 607 515 73 284 393 1216 1272 2000-11-01 56 1 90 583 498 72 281 384 1172 1228 2000-10-01 56 1 87 573 484 72 277 376 1145 1201 2000-09-01 56 1 81 555 458 71 271 367 1095 1151 2000-08-01 56 1 79 537 442 69 262 358 1059 1115 2000-07-01 56 1 77 532 432 67 259 347 1042 1098 2000-06-01 56 1 76 527 426 66 255 344 1030 1086 2000-05-01 56 1 76 514 412 66 250 339 1003 1059 2000-04-01 55 1 73 499 399 65 244 332 972 1027 2000-03-01 55 1 64 483 388 63 232 321 936 991 2000-02-01 55 1 62 466 377 63 222 314 906 961 2000-01-01 55 1 57 452 370 63 216 309 880 935 1999-12-01 54 1 56 442 361 61 208 301 860 914 1999-11-01 54 1 54 429 347 61 204 292 831 885 1999-10-01 54 1 54 413 333 60 199 287 801 855 1999-09-01 52 1 54 396 318 59 193 283 769 821 1999-08-01 52 1 54 396 316 59 193 283 767 819 1999-07-01 52 1 54 391 311 58 191 279 757 809 1999-06-01 52 1 51 384 301 57 186 276 737 789 1999-05-01 52 1 49 372 295 53 178 266 717 769 1999-04-01 52 1 48 359 288 52 174 258 696 748 1999-03-01 52 1 47 349 283 52 173 257 680 732 1999-02-01 52 1 47 339 278 52 170 254 665 717 1999-01-01 52 1 45 334 272 52 167 251 652 704 1998-12-01 52 1 41 324 263 52 163 242 629 681 1998-11-01 52 1 38 307 255 50 155 237 601 653 1998-10-01 52 1 36 302 249 50 153 233 588 640 1998-09-01 52 1 29 289 236 49 141 227 555 607 1998-08-01 52 1 29 279 225 47 134 221 534 586 1998-07-01 52 1 29 276 222 45 130 218 528 580 1998-06-01 52 1 29 270 215 44 128 214 515 567 1998-05-01 52 1 29 261 209 44 125 210 500 552 1998-04-01 52 1 27 253 200 44 118 209 481 533 1998-03-01 52 1 27 241 192 44 113 205 461 513 1998-02-01 52 0 26 237 192 43 111 204 455 507 1998-01-01 52 0 26 232 189 43 109 201 447 499 1997-01-01 52 0 22 203 169 41 98 189 394 446 1996-01-01 52 0 20 176 153 39 87 183 349 401 1995-01-01 52 0 19 162 136 38 84 173 317 369 1994-01-01 50 0 15 139 117 34 71 156 271 321 1993-01-01 50 0 13 116 101 32 65 142 230 280 1992-01-01 50 0 11 102 86 30 62 124 199 249 1991-01-01 48 0 9 75 75 25 50 107 159 207 1990-01-01 48 0 8 62 64 21 43 91 134 182 1980-01-01 44 0 3 27 23 13 18 45 53 97 1970-01-01 42 0 0 13 14 9 11 24 27 69 1960-01-01 41 0 0 10 10 8 9 18 20 61 1950-01-01 41 0 0 7 6 5 6 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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