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	56	16	14	1	0	6	1931
2002 (2)	128	89	6	7	0	0	5	2166
2003 (1)	102	30	23	33	0	0	9	2363
2003 (2)	133	38	33	21	8	0	8	2604
2004 (1)	167	19	41	14	25	0	6	2876
2004 (2)	137	7	29	25	60	0	6	3140
2005 (1)	78	8	28	22	116	0	10	3402
2005 (2)	59	30	54	19	193	0	10	3767
2006 (1)	44	4	45	13	197	0	3	4073
2006 (2)	52	18	54	7	200	0	5	4409
2007 (1)	38	4	20	7	200	0	3	4681
2007 (2)	74	0	25	5	266	0	7	5058
2008 (1)	74	0	43	1	281	0	5	5462
2008 (2)	66	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)*	20	0	12	0	298	101	6	8894

* Incomplete half-year (based on discovery data through 2012-May-20 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) 20 10 0 1 0 0 1 544

2003 (1) 16 3 1 6 0 0 2 572

2003 (2) 17 5 1 4 2 0 1 602

2004 (1) 16 5 1 2 3 0 1 630

2004 (2) 8 1 0 1 13 0 0 653

2005 (1) 10 0 2 1 9 0 1 676

2005 (2) 6 5 5 0 10 0 1 703

2006 (1) 3 0 2 1 9 0 0 718

2006 (2) 1 0 3 0 12 0 0 734

2007 (1) 2 0 3 0 10 0 1 750

2007 (2) 5 0 1 0 7 0 0 763

2008 (1) 2 0 1 0 8 0 0 774

2008 (2) 3 0 1 0 5 0 0 783

2009 (1) 1 0 0 0 8 0 0 792

2009 (2) 6 0 0 0 6 0 2 806

2010 (1) 0 0 1 0 5 0 3 815

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

2011 (1) 1 0 0 0 6 1 0 829

2011 (2) 0 0 1 0 6 4 0 840

2012 (1)* 0 0 0 0 5 0 0 845

* Incomplete half-year (based on discovery data through 2012-May-20 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 ---------- ---- ----- ---- ------ ---- ------ ---- ------ ---- ---- 2012-05-19 91 11 704 4835 3344 153 1307 845 8894 8985 2012-05-01 91 11 703 4819 3329 153 1304 844 8862 8953 2012-04-01 91 11 701 4769 3302 153 1298 843 8783 8874 2012-03-01 91 11 695 4689 3275 153 1291 841 8670 8761 2012-02-01 91 11 686 4641 3234 153 1284 841 8572 8663 2012-01-01 91 11 676 4571 3199 153 1276 840 8457 8548 2011-12-01 91 11 672 4539 3174 153 1269 836 8396 8487 2011-11-01 91 11 669 4498 3139 151 1259 833 8317 8408 2011-10-01 91 11 662 4436 3094 150 1248 832 8203 8294 2011-09-01 90 11 661 4401 3039 150 1242 830 8112 8202 2011-08-01 90 11 661 4385 3013 150 1239 829 8070 8160 2011-07-01 89 11 659 4372 2989 150 1235 829 8031 8120 2011-06-01 89 11 659 4355 2963 150 1230 828 7988 8077 2011-05-01 89 11 656 4328 2942 150 1220 827 7937 8026 2011-04-01 89 11 645 4278 2912 150 1213 825 7846 7935 2011-03-01 89 11 634 4215 2888 150 1203 823 7748 7837 2011-02-01 89 11 624 4168 2870 150 1192 823 7673 7762 2011-01-01 89 11 618 4092 2838 150 1176 821 7559 7648 2010-12-01 89 10 609 4037 2806 150 1167 820 7462 7551 2010-11-01 89 10 598 3968 2760 150 1161 820 7336 7425 2010-10-01 89 10 588 3912 2720 150 1147 820 7230 7319 2010-09-01 89 10 582 3866 2655 150 1142 819 7113 7202 2010-08-01 89 10 579 3852 2645 150 1139 817 7086 7175 2010-07-01 89 10 574 3830 2633 150 1137 815 7047 7136 2010-06-01 88 10 568 3799 2610 150 1129 813 6987 7075 2010-05-01 87 10 560 3756 2590 149 1116 811 6916 7003 2010-04-01 87 10 552 3709 2574 149 1110 811 6845 6932 2010-03-01 87 10 544 3672 2549 148 1101 810 6775 6862 2010-02-01 87 10 540 3618 2524 147 1089 808 6692 6779 2010-01-01 87 10 535 3592 2505 147 1086 806 6642 6729 2009-12-01 87 10 531 3571 2495 147 1081 804 6607 6694 2009-11-01 86 10 520 3495 2467 147 1073 801 6492 6578 2009-10-01 86 10 511 3440 2434 147 1069 799 6395 6481 2009-09-01 86 10 506 3387 2387 147 1059 797 6290 6376 2009-08-01 86 10 504 3367 2360 147 1057 796 6241 6327 2009-07-01 86 10 504 3357 2351 146 1055 792 6222 6308 2009-06-01 85 10 501 3344 2341 145 1052 791 6196 6281 2009-05-01 85 10 499 3317 2328 145 1043 790 6154 6239 2009-04-01 85 10 496 3285 2314 145 1039 788 6105 6190 2009-03-01 85 10 491 3223 2295 145 1027 788 6019 6104 2009-02-01 85 10 487 3166 2268 144 1015 785 5931 6016 2009-01-01 85 10 481 3121 2248 144 1006 783 5860 5945 2008-12-01 84 10 480 3079 2218 144 996 782 5787 5871 2008-11-01 84 10 474 3031 2196 144 987 780 5711 5795 2008-10-01 84 9 467 2970 2146 143 977 779 5592 5676 2008-09-01 83 9 464 2939 2112 143 967 778 5524 5607 2008-08-01 83 9 461 2925 2098 143 962 777 5493 5576 2008-07-01 83 9 459 2907 2087 142 953 774 5462 5545 2008-06-01 83 9 455 2896 2079 142 950 773 5439 5522 2008-05-01 83 9 451 2866 2062 142 944 773 5388 5471 2008-04-01 83 9 449 2819 2033 142 941 772 5310 5393 2008-03-01 83 8 440 2751 2008 141 931 765 5207 5290 2008-02-01 83 8 428 2692 1977 140 917 763 5105 5188 2008-01-01 83 8 426 2664 1960 140 908 763 5058 5141 2007-12-01 83 8 423 2629 1943 140 899 760 5003 5086 2007-11-01 83 8 411 2571 1907 140 889 756 4897 4980 2007-10-01 82 8 397 2522 1865 140 878 755 4792 4874 2007-09-01 82 8 390 2484 1833 139 871 754 4715 4797 2007-08-01 82 8 388 2473 1823 138 866 750 4692 4774 2007-07-01 82 8 388 2469 1816 138 865 750 4681 4763 2007-06-01 82 8 383 2447 1807 137 856 747 4645 4727 2007-05-01 82 8 382 2435 1795 137 852 745 4620 4702 2007-04-01 82 8 381 2410 1778 137 848 741 4577 4659 2007-03-01 82 7 375 2371 1754 137 841 739 4507 4589 2007-02-01 82 7 367 2338 1738 136 833 735 4450 4532 2007-01-01 82 7 359 2318 1725 136 824 734 4409 4491 2006-12-01 81 7 354 2291 1707 136 821 732 4359 4440 2006-11-01 81 6 344 2242 1683 135 809 725 4275 4356 2006-10-01 79 6 337 2212 1651 135 799 723 4206 4285 2006-09-01 79 6 330 2176 1622 134 790 719 4134 4213 2006-08-01 79 6 328 2159 1609 134 785 719 4102 4181 2006-07-01 79 6 327 2148 1592 134 783 718 4073 4152 2006-06-01 79 6 326 2137 1579 134 780 718 4048 4127 2006-05-01 79 5 325 2109 1552 134 770 714 3991 4070 2006-04-01 78 5 321 2082 1537 134 760 712 3945 4023 2006-03-01 78 5 319 2066 1518 134 759 711 3908 3986 2006-02-01 78 5 316 2031 1501 134 751 708 3853 3931 2006-01-01 78 5 312 1976 1474 133 742 703 3767 3845 2005-12-01 78 5 302 1944 1453 132 731 700 3704 3782 2005-11-01 77 5 297 1902 1427 131 721 695 3631 3708 2005-10-01 76 4 289 1846 1387 130 709 684 3526 3602 2005-09-01 76 4 286 1812 1368 130 704 681 3470 3546 2005-08-01 76 4 283 1798 1352 130 698 679 3437 3513 2005-07-01 76 4 279 1779 1340 129 691 676 3402 3478 2005-06-01 76 4 275 1764 1320 129 687 671 3363 3439 2005-05-01 75 4 274 1747 1305 127 681 668 3330 3405 2005-04-01 75 4 268 1722 1286 125 668 664 3280 3355 2005-03-01 75 4 263 1681 1262 124 658 660 3210 3285 2005-02-01 75 4 262 1657 1255 123 654 657 3178 3253 2005-01-01 75 4 258 1633 1245 123 647 653 3140 3215 2004-12-01 74 3 249 1601 1224 123 638 645 3077 3151 2004-11-01 74 3 245 1581 1218 122 629 640 3047 3121 2004-10-01 73 3 238 1553 1210 121 618 638 3004 3077 2004-09-01 72 3 230 1515 1185 121 610 637 2933 3005 2004-08-01 72 3 226 1496 1162 120 603 633 2887 2959 2004-07-01 72 3 226 1490 1157 118 600 630 2876 2948 2004-06-01 72 3 223 1460 1144 117 589 627 2830 2902 2004-05-01 72 2 218 1441 1129 117 583 623 2790 2862 2004-04-01 72 2 215 1411 1117 113 573 616 2745 2817 2004-03-01 72 2 206 1375 1099 113 566 607 2682 2754 2004-02-01 71 2 204 1360 1092 112 561 606 2658 2729 2004-01-01 71 2 202 1326 1074 110 551 602 2604 2675 2003-12-01 71 2 196 1294 1062 107 539 594 2554 2625 2003-11-01 71 2 193 1272 1049 107 531 588 2516 2587 2003-10-01 71 2 188 1245 1027 107 522 586 2462 2533 2003-09-01 71 2 185 1225 993 105 513 579 2405 2476 2003-08-01 71 2 185 1213 980 102 508 575 2380 2451 2003-07-01 70 2 184 1206 971 102 505 572 2363 2433 2003-06-01 70 2 182 1190 959 102 500 566 2333 2403 2003-05-01 68 2 180 1176 953 101 498 564 2311 2379 2003-04-01 68 2 175 1156 942 101 491 559 2275 2343 2003-03-01 68 2 170 1137 931 101 484 555 2240 2308 2003-02-01 68 1 169 1117 925 101 479 551 2212 2280 2003-01-01 68 1 167 1090 908 100 469 544 2166 2234 2002-12-01 68 1 163 1063 888 100 467 542 2115 2183 2002-11-01 68 1 160 1048 871 99 461 538 2080 2148 2002-10-01 67 1 158 1024 848 98 455 529 2031 2098 2002-09-01 65 1 155 1004 829 97 449 521 1989 2054 2002-08-01 65 1 154 988 806 95 438 517 1949 2014 2002-07-01 64 1 152 978 800 94 431 512 1931 1995 2002-06-01 64 1 148 960 792 92 422 506 1901 1965 2002-05-01 64 1 144 942 781 91 413 495 1868 1932 2002-04-01 64 1 142 924 768 91 406 493 1835 1899 2002-03-01 63 1 136 897 754 90 396 489 1788 1851 2002-02-01 63 1 131 874 738 89 387 479 1744 1807 2002-01-01 63 1 124 840 715 89 374 470 1680 1743 2001-12-01 63 1 121 804 696 85 360 461 1622 1685 2001-11-01 61 1 120 776 681 83 352 456 1578 1639 2001-10-01 61 1 114 750 658 82 342 452 1523 1584 2001-09-01 61 1 110 721 623 81 331 439 1455 1516 2001-08-01 60 1 109 699 603 81 325 437 1412 1472 2001-07-01 59 1 108 694 590 81 324 436 1393 1452 2001-06-01 58 1 108 684 579 79 321 429 1372 1430 2001-05-01 57 1 107 672 568 77 314 421 1348 1405 2001-04-01 57 1 105 660 559 76 305 417 1325 1382 2001-03-01 57 1 101 645 545 74 296 409 1292 1349 2001-02-01 57 1 98 634 534 73 293 404 1267 1324 2001-01-01 57 1 94 619 525 73 290 400 1239 1296 2000-12-01 57 1 93 605 513 72 284 393 1212 1269 2000-11-01 57 1 90 581 496 71 281 384 1168 1225 2000-10-01 57 1 87 571 482 71 277 376 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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