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)	Pan-STARRS (F51)	Other	Cumulative Total
1995 (1)	0	0	14	0	0	0	4	334
1995 (2)	0	0	12	0	0	0	2	348
1996 (1)	1	5	18	0	0	0	4	376
1996 (2)	0	5	10	0	0	0	2	393
1997 (1)	3	2	10	0	0	0	4	412
1997 (2)	14	9	4	0	0	0	7	446
1998 (1)	44	9	19	1	1	0	7	527
1998 (2)	92	2	16	6	2	0	5	650
1999 (1)	74	0	12	6	11	0	1	754
1999 (2)	87	0	7	7	19	0	3	877
2000 (1)	108	2	14	21	13	0	4	1039
2000 (2)	150	13	12	17	0	0	8	1239
2001 (1)	95	28	7	22	0	0	2	1393
2001 (2)	184	64	15	20	0	0	4	1680
2002 (1)	158	55	16	14	1	0	6	1930
2002 (2)	128	89	6	7	0	0	5	2165
2003 (1)	102	30	23	33	0	0	9	2362
2003 (2)	133	38	33	21	8	0	8	2603
2004 (1)	167	19	41	14	25	0	6	2875
2004 (2)	137	7	29	25	60	0	6	3139
2005 (1)	78	8	28	22	116	0	10	3401
2005 (2)	59	30	54	19	193	0	10	3766
2006 (1)	44	4	45	13	197	0	3	4072
2006 (2)	52	18	54	7	200	0	5	4408
2007 (1)	38	4	20	7	200	0	3	4680
2007 (2)	74	0	25	5	266	0	7	5057
2008 (1)	74	0	43	1	281	0	5	5461
2008 (2)	67	0	43	0	278	0	11	5860
2009 (1)	50	0	32	0	262	0	18	6222
2009 (2)	58	0	31	0	314	0	17	6642
2010 (1)	29	0	21	0	257	0	98	7047
2010 (2)	75	0	22	0	345	18	52	7559
2011 (1)	40	0	17	0	333	68	14	8031
2011 (2)	30	0	15	0	253	105	23	8457
2012 (1)*	8	0	1	0	97	19	0	8582

* Incomplete half-year (based on discovery data through 2012-Feb-07 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) Pan-STARRS
(F51) Other Cumulative
Total

1995 (1) 0 0 3 0 0 0 2 177

1995 (2) 0 0 4 0 0 0 1 182

1996 (1) 0 2 2 0 0 0 0 186

1996 (2) 0 2 0 0 0 0 0 188

1997 (1) 0 1 2 0 0 0 1 192

1997 (2) 2 3 1 0 0 0 2 200

1998 (1) 8 4 2 1 0 0 2 217

1998 (2) 24 2 1 3 0 0 3 250

1999 (1) 16 0 2 4 4 0 0 276

1999 (2) 24 0 1 1 3 0 2 307

2000 (1) 31 2 1 1 4 0 1 347

2000 (2) 39 2 3 5 0 0 4 400

2001 (1) 24 8 0 4 0 0 0 436

2001 (2) 25 4 0 4 0 0 1 470

2002 (1) 32 4 2 3 0 0 1 512

2002 (2) 21 10 0 1 0 0 1 545

2003 (1) 16 3 1 6 0 0 2 573

2003 (2) 17 5 1 4 2 0 1 603

2004 (1) 16 5 1 2 3 0 1 631

2004 (2) 8 1 0 1 13 0 0 654

2005 (1) 10 0 2 1 9 0 1 677

2005 (2) 6 5 5 0 10 0 1 704

2006 (1) 3 0 2 1 9 0 0 719

2006 (2) 1 0 3 0 12 0 0 735

2007 (1) 2 0 3 0 10 0 1 751

2007 (2) 5 0 1 0 7 0 0 764

2008 (1) 2 0 1 0 8 0 0 775

2008 (2) 3 0 1 0 5 0 0 784

2009 (1) 1 0 1 0 8 0 0 794

2009 (2) 6 0 0 0 6 0 2 808

2010 (1) 0 0 0 0 4 0 3 815

2010 (2) 1 0 0 0 1 0 4 821

2011 (1) 1 0 0 0 6 0 0 828

2011 (2) 0 0 1 0 6 4 0 839

2012 (1)* 0 0 0 0 1 0 0 840

* Incomplete half-year (based on discovery data through 2012-Feb-07 06:05 local)
NOTE: In the year 2010, the "Other" site category was exclusively WISE.
A separate table of WISE discoveries is available.

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 ---------- ---- ----- ---- ------ ---- ------ ---- ------ ---- ---- 2012-02-03 90 11 687 4643 3241 152 1285 840 8582 8672 2012-02-01 90 11 686 4641 3232 152 1285 840 8570 8660 2012-01-01 90 11 676 4572 3198 152 1277 839 8457 8547 2011-12-01 90 11 672 4540 3173 152 1270 835 8396 8486 2011-11-01 90 11 669 4499 3138 150 1260 832 8317 8407 2011-10-01 90 11 662 4437 3093 149 1248 831 8203 8293 2011-09-01 90 11 661 4402 3038 149 1242 829 8112 8202 2011-08-01 90 11 661 4386 3012 149 1239 828 8070 8160 2011-07-01 89 11 659 4373 2988 149 1235 828 8031 8120 2011-06-01 89 11 659 4356 2962 149 1230 827 7988 8077 2011-05-01 89 11 656 4329 2941 149 1220 826 7937 8026 2011-04-01 89 11 645 4279 2911 149 1213 825 7846 7935 2011-03-01 89 11 634 4216 2887 149 1203 823 7748 7837 2011-02-01 89 11 624 4169 2869 149 1192 823 7673 7762 2011-01-01 89 11 618 4093 2837 149 1176 821 7559 7648 2010-12-01 89 10 609 4038 2805 149 1167 820 7462 7551 2010-11-01 89 10 598 3969 2759 149 1161 820 7336 7425 2010-10-01 89 10 588 3913 2719 149 1147 820 7230 7319 2010-09-01 89 10 582 3867 2654 149 1142 819 7113 7202 2010-08-01 89 10 579 3853 2644 149 1139 817 7086 7175 2010-07-01 89 10 574 3831 2632 149 1137 815 7047 7136 2010-06-01 88 10 568 3800 2609 149 1129 814 6987 7075 2010-05-01 87 10 560 3757 2589 148 1116 812 6916 7003 2010-04-01 87 10 552 3710 2573 148 1110 812 6845 6932 2010-03-01 87 10 544 3673 2548 148 1101 812 6775 6862 2010-02-01 87 10 540 3619 2523 147 1089 810 6692 6779 2010-01-01 87 10 535 3593 2504 147 1086 808 6642 6729 2009-12-01 87 10 531 3572 2494 147 1081 806 6607 6694 2009-11-01 86 10 520 3496 2466 147 1073 803 6492 6578 2009-10-01 86 10 511 3441 2433 147 1069 801 6395 6481 2009-09-01 86 10 506 3388 2386 147 1059 799 6290 6376 2009-08-01 86 10 504 3368 2359 147 1057 798 6241 6327 2009-07-01 86 10 504 3358 2350 146 1055 794 6222 6308 2009-06-01 85 10 501 3345 2340 145 1052 793 6196 6281 2009-05-01 85 10 499 3318 2327 145 1043 791 6154 6239 2009-04-01 85 10 496 3286 2313 145 1039 789 6105 6190 2009-03-01 85 10 491 3224 2294 145 1027 789 6019 6104 2009-02-01 85 10 487 3167 2267 144 1015 786 5931 6016 2009-01-01 85 10 481 3122 2247 144 1006 784 5860 5945 2008-12-01 84 10 480 3080 2217 144 996 783 5787 5871 2008-11-01 84 10 474 3032 2195 144 987 781 5711 5795 2008-10-01 84 9 467 2971 2145 143 977 780 5592 5676 2008-09-01 83 9 464 2940 2111 143 967 779 5524 5607 2008-08-01 83 9 461 2925 2097 143 961 778 5492 5575 2008-07-01 83 9 459 2907 2086 142 952 775 5461 5544 2008-06-01 83 9 455 2896 2078 142 949 774 5438 5521 2008-05-01 83 9 451 2866 2061 142 943 774 5387 5470 2008-04-01 83 9 449 2819 2032 142 940 773 5309 5392 2008-03-01 83 8 440 2751 2007 141 930 766 5206 5289 2008-02-01 83 8 428 2692 1976 140 916 764 5104 5187 2008-01-01 83 8 426 2664 1959 140 907 764 5057 5140 2007-12-01 83 8 423 2629 1942 140 898 761 5002 5085 2007-11-01 83 8 411 2571 1906 140 888 757 4896 4979 2007-10-01 82 8 397 2522 1864 140 877 756 4791 4873 2007-09-01 82 8 390 2484 1832 139 870 755 4714 4796 2007-08-01 82 8 388 2473 1822 138 865 751 4691 4773 2007-07-01 82 8 388 2469 1815 138 864 751 4680 4762 2007-06-01 82 8 383 2447 1806 137 855 748 4644 4726 2007-05-01 82 8 382 2435 1794 137 851 746 4619 4701 2007-04-01 82 8 381 2410 1777 137 847 742 4576 4658 2007-03-01 82 7 375 2371 1753 137 840 740 4506 4588 2007-02-01 82 7 367 2338 1737 136 832 736 4449 4531 2007-01-01 82 7 359 2318 1724 136 823 735 4408 4490 2006-12-01 81 7 354 2291 1706 136 820 733 4358 4439 2006-11-01 81 6 344 2242 1682 135 808 726 4274 4355 2006-10-01 79 6 337 2212 1650 135 798 724 4205 4284 2006-09-01 79 6 330 2176 1621 134 789 720 4133 4212 2006-08-01 79 6 328 2159 1608 134 784 720 4101 4180 2006-07-01 79 6 327 2148 1591 134 782 719 4072 4151 2006-06-01 79 6 326 2137 1578 134 779 719 4047 4126 2006-05-01 79 5 325 2109 1551 134 769 715 3990 4069 2006-04-01 78 5 321 2082 1536 134 759 713 3944 4022 2006-03-01 78 5 319 2066 1517 134 758 712 3907 3985 2006-02-01 78 5 316 2031 1500 134 750 709 3852 3930 2006-01-01 78 5 312 1976 1473 133 741 704 3766 3844 2005-12-01 78 5 302 1944 1452 132 730 701 3703 3781 2005-11-01 77 5 297 1902 1426 131 720 696 3630 3707 2005-10-01 76 4 289 1846 1386 130 708 685 3525 3601 2005-09-01 76 4 286 1812 1367 130 703 682 3469 3545 2005-08-01 76 4 283 1798 1351 130 697 680 3436 3512 2005-07-01 76 4 279 1779 1339 129 690 677 3401 3477 2005-06-01 76 4 275 1764 1319 129 686 672 3362 3438 2005-05-01 75 4 274 1747 1304 127 680 669 3329 3404 2005-04-01 75 4 268 1722 1285 125 667 665 3279 3354 2005-03-01 75 4 263 1681 1261 124 657 661 3209 3284 2005-02-01 75 4 262 1657 1254 123 653 658 3177 3252 2005-01-01 75 4 258 1633 1244 123 646 654 3139 3214 2004-12-01 74 3 249 1601 1223 123 637 646 3076 3150 2004-11-01 74 3 245 1581 1217 122 628 641 3046 3120 2004-10-01 73 3 238 1553 1209 121 617 639 3003 3076 2004-09-01 72 3 230 1515 1184 121 609 638 2932 3004 2004-08-01 72 3 226 1496 1161 120 602 634 2886 2958 2004-07-01 72 3 226 1490 1156 118 599 631 2875 2947 2004-06-01 72 3 223 1460 1143 117 588 628 2829 2901 2004-05-01 72 2 218 1441 1128 117 582 624 2789 2861 2004-04-01 72 2 215 1411 1116 113 572 617 2744 2816 2004-03-01 72 2 206 1375 1098 113 565 608 2681 2753 2004-02-01 71 2 204 1360 1091 112 560 607 2657 2728 2004-01-01 71 2 202 1326 1073 110 550 603 2603 2674 2003-12-01 71 2 196 1294 1061 107 538 595 2553 2624 2003-11-01 71 2 193 1272 1048 107 530 589 2515 2586 2003-10-01 71 2 188 1245 1026 107 521 587 2461 2532 2003-09-01 71 2 185 1225 992 105 512 580 2404 2475 2003-08-01 71 2 185 1213 979 102 507 576 2379 2450 2003-07-01 70 2 184 1206 970 102 504 573 2362 2432 2003-06-01 70 2 182 1190 958 102 499 567 2332 2402 2003-05-01 68 2 180 1176 952 101 497 565 2310 2378 2003-04-01 68 2 175 1156 941 101 490 560 2274 2342 2003-03-01 68 2 170 1137 930 101 483 556 2239 2307 2003-02-01 68 1 169 1117 924 101 478 552 2211 2279 2003-01-01 68 1 167 1090 907 100 468 545 2165 2233 2002-12-01 68 1 163 1063 887 100 466 543 2114 2182 2002-11-01 68 1 160 1048 870 99 460 539 2079 2147 2002-10-01 67 1 158 1024 847 98 454 530 2030 2097 2002-09-01 65 1 155 1004 828 97 448 521 1988 2053 2002-08-01 65 1 154 988 805 95 437 517 1948 2013 2002-07-01 64 1 152 978 799 94 430 512 1930 1994 2002-06-01 64 1 148 960 791 92 421 506 1900 1964 2002-05-01 64 1 144 942 780 91 412 495 1867 1931 2002-04-01 64 1 142 924 767 91 405 493 1834 1898 2002-03-01 63 1 136 897 754 90 395 489 1788 1851 2002-02-01 63 1 131 874 738 89 386 479 1744 1807 2002-01-01 63 1 124 840 715 89 373 470 1680 1743 2001-12-01 63 1 121 804 696 85 359 461 1622 1685 2001-11-01 61 1 120 776 681 83 351 456 1578 1639 2001-10-01 61 1 114 750 658 82 341 452 1523 1584 2001-09-01 61 1 110 721 623 81 330 439 1455 1516 2001-08-01 60 1 109 699 603 81 324 437 1412 1472 2001-07-01 59 1 108 694 590 81 323 436 1393 1452 2001-06-01 58 1 108 684 579 79 320 429 1372 1430 2001-05-01 57 1 107 672 568 77 313 421 1348 1405 2001-04-01 57 1 105 660 559 76 304 417 1325 1382 2001-03-01 57 1 101 645 545 74 295 409 1292 1349 2001-02-01 57 1 98 634 534 73 292 404 1267 1324 2001-01-01 57 1 94 619 525 73 289 400 1239 1296 2000-12-01 57 1 93 605 513 72 283 393 1212 1269 2000-11-01 57 1 90 581 496 71 280 384 1168 1225 2000-10-01 57 1 87 571 482 71 276 376 1141 1198 2000-09-01 57 1 81 553 456 70 270 367 1091 1148 2000-08-01 57 1 79 535 440 68 261 358 1055 1112 2000-07-01 57 1 77 530 431 66 258 347 1039 1096 2000-06-01 57 1 76 525 425 65 254 344 1027 1084 2000-05-01 57 1 76 512 411 65 249 338 1000 1057 2000-04-01 56 1 73 497 398 64 243 331 969 1025 2000-03-01 56 1 64 481 387 62 231 319 933 989 2000-02-01 56 1 62 464 376 62 221 312 903 959 2000-01-01 56 1 57 450 369 62 215 307 877 933 1999-12-01 55 1 56 440 360 60 207 299 857 912 1999-11-01 55 1 54 427 346 60 203 289 828 883 1999-10-01 55 1 54 411 332 59 198 284 798 853 1999-09-01 53 1 54 394 317 58 192 280 766 819 1999-08-01 53 1 54 394 315 58 192 280 764 817 1999-07-01 53 1 54 389 310 57 190 276 754 807 1999-06-01 53 1 51 382 300 56 185 273 734 787 1999-05-01 52 1 49 370 295 52 177 264 715 767 1999-04-01 52 1 48 357 288 51 173 256 694 746 1999-03-01 52 1 47 347 283 51 172 255 678 730 1999-02-01 52 1 47 337 278 51 169 252 663 715 1999-01-01 52 1 45 332 272 51 166 250 650 702 1998-12-01 52 1 41 322 263 51 162 241 627 679 1998-11-01 52 1 38 307 254 49 154 236 600 652 1998-10-01 52 1 36 302 248 49 152 232 587 639 1998-09-01 52 1 29 289 235 48 140 226 554 606 1998-08-01 52 1 29 279 224 46 133 220 533 585 1998-07-01 52 1 29 276 221 44 129 217 527 579 1998-06-01 52 1 29 270 214 43 127 213 514 566 1998-05-01 52 1 29 261 208 43 124 209 499 551 1998-04-01 52 1 27 253 199 43 117 208 480 532 1998-03-01 52 1 27 242 190 43 112 204 460 512 1998-02-01 52 0 26 238 190 42 110 203 454 506 1998-01-01 52 0 26 233 187 42 108 200 446 498 1997-01-01 52 0 22 204 167 40 97 188 393 445 1996-01-01 52 0 20 177 151 38 86 182 348 400 1995-01-01 52 0 19 163 134 37 83 172 316 368 1994-01-01 50 0 15 140 115 33 70 155 270 320 1993-01-01 50 0 13 117 99 31 64 141 229 279 1992-01-01 50 0 11 103 85 29 61 124 199 249 1991-01-01 48 0 9 76 74 24 49 106 159 207 1990-01-01 48 0 8 63 63 20 42 90 134 182 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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