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NEO Discovery Statistics

NEAR-EARTH ASTEROID DISCOVERY STATISTICS

Some entries in the following charts and tables are dependent upon a diameter that is roughly inferred from the object’s estimated absolute magnitude (H) and its assumed reflectivity, or albedo. The absolute magnitude (H) of a near-Earth asteroid (NEA) 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. 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.

Since most NEAs do not have a known reflectivity, or albedo, this albedo must be estimated before the H values, representing intrinsic brightness, can be converted to an approximate diameter. Pravec et al (2012) determined that, for their sample of 583 main-belt asteroids and NEAs, the mean albedos and their standard deviations are 0.057 (±0.013) for the Tholen/Bus/DeMeo C/G/B/F/P/D types and 0.197 (±0.051) for the S/A/L types. Since the albedos for NEAs are most likely to be either approximately 6% for asteroids of the C-type and associated taxonomic classes or 20% for asteroids of the more populous S-type and associated taxonomic classes, we have used an approximate mean value of 14% albedo and an H value of 17.75 to represent a one kilometer spherical NEA. Since the determined H values are uncertain, and likely biased by a few tenths (see Pravec et al., 2012, Icarus) and the single 14% albedo is only a rough mean representing a bimodal albedo distribution, the estimated numbers of one kilometer and larger sized objects in the tables below are very rough. However, these statistics are useful for monitoring the annual NEA discovery progress.

Using near-infrared data provided by the WISE spacecraft in 2010 and early 2011, Mainzer et al (2011) were able to determine diameters and albedos for 250 NEAs with a minimum uncertainty of 10% and 20% respectively. Hence they were able to determine the albedo distribution of these objects with known diameters and this distribution was then used to compute diameters for previously known NEOs with known H values but unknown diameters or albedos. They provided an estimate of 981 (±19) NEAs as the total population of NEAs one kilometer and larger. At the time of their analysis (Spring 2011), they also estimated that 911 (±17) of these large NEAs had already been discovered. While this latter estimate is both higher and more accurate than the estimated numbers given for Spring 2011 in the following tables, this statistical technique cannot be easily employed for day-to-day estimates of the population of NEAs one kilometer and larger. In the following tables, we will continue to use the simpler method described in the previous paragraph.

Mainzer, A. et al. (2011). NEOWISE observations of near-Earth objects: Preliminary Results. Astrophysical Journal. 743:156.
Pravec, P., A.W. Harris, P. Kusnirak, A. Galad, K. Hornoch (2012). Absolute magnitudes of asteroids and a revision of asteroid albedo estimates from WISE thermal observations. Icarus (submitted 6/2012).
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: Number of Near-Earth Asteroid Discoveries at Half-Year Intervals: 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)
NEOWISE
(C51)
OtherCumulative
Total
 1995 (1)001400004334
 1995 (2)001201002349
 1996 (1)151800004377
 1996 (2)051000002394
 1997 (1)321000004413
 1997 (2)149400007447
 1998 (1)4491911007528
 1998 (2)9221563005651
 1999 (1)75012611001756
 1999 (2)8707719003879
 2000 (1)10821421130041041
 2000 (2)15014121700081242
 2001 (1)942872200021395
 2001 (2)18364152000041681
 2002 (1)15857161410061933
 2002 (2)130896700052170
 2003 (1)10230233300092367
 2003 (2)13337332270082607
 2004 (1)167194114250062879
 2004 (2)13772925600063143
 2005 (1)778292211500103404
 2005 (2)5930541919300103769
 2006 (1)44445131950034073
 2006 (2)52175461990054406
 2007 (1)3842072000034678
 2007 (2)7402552660075055
 2008 (1)7404312800055458
 2008 (2)66043028000115858
 2009 (1)51032026000186219
 2009 (2)58031031500176640
 2010 (1)29021025808797044
 2010 (2)7502203461737147555
 2011 (1)410170328683128024
 2011 (2)2901502521040238447
 2012 (1)260130352120078965
 2012 (2)2901302771310269441
 2013 (1)301302881510189914
 2013 (2)0012031520812910479
 2014 (1)00803322411614611222
 2014 (2)0080285380243811957
 2015 (1)*000019826010712432
* Incomplete half-year (based on discovery data through 2015-Apr-18 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)
NEOWISE
(C51)
OtherCumulative
Total
 1995 (1)00300002176
 1995 (2)00400001181
 1996 (1)02200000185
 1996 (2)02000000187
 1997 (1)01300001192
 1997 (2)23100002200
 1998 (1)74210002216
 1998 (2)242131003250
 1999 (1)160244000276
 1999 (2)230112002305
 2000 (1)332114001347
 2000 (2)372350004398
 2001 (1)238040000433
 2001 (2)225040001465
 2002 (1)294230001504
 2002 (2)1910010001535
 2003 (1)143260002562
 2003 (2)175142001592
 2004 (1)155123001619
 2004 (2)910112000642
 2005 (1)100219001665
 2005 (2)645010001691
 2006 (1)30219000706
 2006 (2)102012000721
 2007 (1)20309001736
 2007 (2)50107000749
 2008 (1)20108000760
 2008 (2)30105000769
 2009 (1)10109000780
 2009 (2)60006002794
 2010 (1)00004030801
 2010 (2)10002030807
 2011 (1)20005100815
 2011 (2)00106300825
 2012 (1)00009100835
 2012 (2)10005200843
 2013 (1)00004000847
 2013 (2)00003201853
 2014 (1)00002420861
 2014 (2)00001210865
 2015 (1)*00000510871
* Incomplete half-year (based on discovery data through 2015-Apr-18 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
With over 90% of the near-Earth objects larger than one kilometer already discovered, the NEO Program is now focusing on finding 90% of the NEO population larger than 140 meters. 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).
Table: Number of Known Near-Earth Asteroids Over Time
(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. Numbers for large asteroids (PHA-KM and NEA-KM) are rough estimates (see introductory note above). 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
----------  ----  ----- ----- ------ -----  ------ ----  ------ -----  -----
2015-04-16   101     15   916   6752  4749     152 1578     871 12432  12533
2015-04-01   101     15   916   6726  4740     152 1575     871 12397  12498
2015-03-01   100     15   905   6621  4704     152 1560     868 12245  12345
2015-02-01   100     14   898   6538  4666     152 1548     868 12116  12216
2015-01-01    99     14   889   6456  4598     152 1534     865 11957  12056
2014-12-01    99     14   880   6392  4561     152 1525     863 11847  11946
2014-11-01    99     14   874   6318  4498     152 1516     861 11704  11803
2014-10-01    98     14   867   6228  4435     152 1511     861 11544  11642
2014-09-01    98     14   861   6175  4380     152 1505     861 11430  11528
2014-08-01    98     14   856   6122  4307     152 1496     861 11299  11397
2014-07-01    98     14   854   6079  4275     152 1486     861 11222  11320
2014-06-01    98     14   845   6042  4218     151 1478     857 11119  11217
2014-05-01    98     14   838   5975  4171     151 1465     855 10998  11096
2014-04-01    98     14   826   5859  4062     151 1457     854 10761  10859
2014-03-01    98     13   819   5803  4035     151 1452     854 10670  10768
2014-02-01    98     13   811   5758  3997     151 1445     854 10579  10677
2014-01-01    98     13   804   5705  3957     151 1441     853 10479  10577
2013-12-01    98     13   799   5650  3931     151 1437     853 10393  10491
2013-11-01    98     13   798   5578  3905     151 1429     853 10294  10392
2013-10-01    97     12   786   5519  3843     150 1422     849 10160  10257
2013-09-01    97     12   780   5462  3788     150 1418     848 10042  10139
2013-08-01    97     12   778   5431  3751     150 1412     848  9972  10069
2013-07-01    97     12   773   5403  3726     150 1405     847  9914  10011
2013-06-01    97     12   770   5373  3708     150 1399     845  9863   9960
2013-05-01    97     11   765   5334  3687     150 1392     845  9797   9894
2013-04-01    97     11   760   5293  3656     150 1383     844  9720   9817
2013-03-01    97     11   755   5245  3627     150 1374     844  9638   9735
2013-02-01    96     11   750   5206  3600     150 1370     844  9567   9663
2013-01-01    96     11   743   5125  3562     150 1356     843  9441   9537
2012-12-01    96     11   735   5072  3531     150 1345     843  9349   9445
2012-11-01    95     10   727   5018  3494     150 1337     840  9249   9344
2012-10-01    95     10   721   4943  3438     150 1326     838  9112   9207
2012-09-01    95     10   717   4910  3408     150 1323     837  9045   9140
2012-08-01    95     10   712   4884  3375     150 1318     836  8981   9076
2012-07-01    94     10   711   4878  3366     150 1314     835  8965   9059
2012-06-01    94     10   706   4853  3342     150 1305     832  8911   9005
2012-05-01    94     10   704   4820  3318     150 1300     829  8852   8946
2012-04-01    94     10   702   4769  3291     150 1294     828  8772   8866
2012-03-01    94     10   696   4689  3264     150 1288     826  8659   8753
2012-02-01    94     10   686   4642  3223     150 1282     826  8561   8655
2012-01-01    94     10   676   4573  3188     150 1273     825  8447   8541
2011-12-01    94     10   672   4541  3163     150 1266     821  8386   8480
2011-11-01    94     10   669   4500  3129     148 1256     818  8308   8402
2011-10-01    94     10   662   4438  3084     147 1245     817  8194   8288
2011-09-01    93     10   661   4403  3031     147 1239     816  8105   8198
2011-08-01    93     10   661   4387  3005     147 1236     815  8063   8156
2011-07-01    92     10   659   4374  2981     147 1232     815  8024   8116
2011-06-01    92     10   659   4357  2956     147 1226     814  7982   8074
2011-05-01    92     10   656   4331  2933     147 1217     812  7930   8022
2011-04-01    92     10   645   4282  2904     147 1210     810  7841   7933
2011-03-01    92     10   634   4219  2880     147 1201     808  7743   7835
2011-02-01    92     10   624   4173  2862     147 1190     808  7669   7761
2011-01-01    92     10   618   4098  2829     147 1174     807  7555   7647
2010-12-01    92      9   609   4043  2798     147 1165     807  7459   7551
2010-11-01    92      9   598   3974  2752     147 1159     807  7333   7425
2010-10-01    92      9   588   3918  2713     147 1145     807  7228   7320
2010-09-01    92      9   582   3871  2648     147 1140     805  7110   7202
2010-08-01    92      9   579   3857  2637     147 1137     802  7082   7174
2010-07-01    92      9   574   3835  2626     147 1135     801  7044   7136
2010-06-01    91      9   568   3804  2604     147 1127     800  6985   7076
2010-05-01    90      9   560   3760  2585     146 1114     798  6914   7004
2010-04-01    90      9   552   3714  2568     146 1108     798  6843   6933
2010-03-01    90      9   544   3677  2542     145 1099     797  6772   6862
2010-02-01    90      9   540   3623  2517     145 1087     796  6689   6779
2010-01-01    90      9   535   3597  2499     145 1084     794  6640   6730
2009-12-01    90      9   531   3576  2489     145 1079     792  6605   6695
2009-11-01    89      9   520   3500  2460     145 1071     789  6489   6578
2009-10-01    89      9   511   3445  2427     145 1067     787  6392   6481
2009-09-01    89      9   506   3392  2380     145 1057     785  6287   6376
2009-08-01    89      9   504   3372  2353     145 1055     784  6238   6327
2009-07-01    89      9   504   3362  2344     144 1053     780  6219   6308
2009-06-01    88      9   501   3351  2333     143 1050     779  6194   6282
2009-05-01    88      9   499   3324  2319     143 1041     777  6151   6239
2009-04-01    88      9   496   3292  2305     143 1037     774  6102   6190
2009-03-01    88      9   491   3231  2286     143 1025     774  6017   6105
2009-02-01    88      9   487   3172  2260     142 1013     771  5928   6016
2009-01-01    88      9   481   3128  2240     142 1004     769  5858   5946
2008-12-01    87      9   480   3086  2211     142  994     768  5786   5873
2008-11-01    87      9   474   3038  2189     142  986     766  5710   5797
2008-10-01    87      8   467   2976  2138     141  976     765  5589   5676
2008-09-01    86      8   464   2945  2103     141  966     764  5520   5606
2008-08-01    86      8   461   2931  2089     141  961     763  5489   5575
2008-07-01    86      8   459   2914  2077     140  952     760  5458   5544
2008-06-01    86      8   455   2903  2069     140  949     759  5435   5521
2008-05-01    86      8   451   2873  2052     140  943     759  5384   5470
2008-04-01    86      8   449   2826  2023     140  940     758  5306   5392
2008-03-01    86      7   440   2758  1998     139  930     751  5203   5289
2008-02-01    86      7   428   2698  1968     138  916     749  5101   5187
2008-01-01    85      7   426   2671  1951     138  908     749  5055   5140
2007-12-01    85      7   423   2636  1934     138  898     746  5000   5085
2007-11-01    85      7   411   2578  1898     138  888     742  4894   4979
2007-10-01    84      7   397   2529  1856     138  877     741  4789   4873
2007-09-01    84      7   390   2491  1824     137  870     740  4712   4796
2007-08-01    84      7   388   2480  1814     136  865     736  4689   4773
2007-07-01    84      7   388   2476  1807     136  864     736  4678   4762
2007-06-01    84      7   383   2454  1798     135  855     734  4642   4726
2007-05-01    84      7   382   2441  1787     135  851     732  4617   4701
2007-04-01    84      7   381   2415  1771     135  847     728  4574   4658
2007-03-01    84      6   375   2375  1748     135  840     726  4504   4588
2007-02-01    84      6   367   2342  1732     134  832     722  4447   4531
2007-01-01    84      6   359   2322  1719     134  823     721  4406   4490
2006-12-01    83      6   354   2296  1701     134  820     719  4357   4440
2006-11-01    83      5   344   2247  1678     133  808     713  4274   4357
2006-10-01    81      5   337   2217  1646     133  798     711  4205   4286
2006-09-01    81      5   330   2180  1619     132  789     707  4134   4215
2006-08-01    81      5   328   2163  1606     132  784     707  4102   4183
2006-07-01    81      5   327   2152  1589     132  782     706  4073   4154
2006-06-01    81      5   326   2141  1576     132  779     706  4048   4129
2006-05-01    81      5   325   2113  1549     132  769     702  3992   4073
2006-04-01    80      5   321   2086  1534     132  759     700  3946   4026
2006-03-01    80      5   319   2071  1515     132  758     699  3910   3990
2006-02-01    80      5   316   2036  1498     132  750     696  3855   3935
2006-01-01    80      5   312   1981  1471     131  741     691  3769   3849
2005-12-01    80      5   302   1949  1450     130  730     688  3706   3786
2005-11-01    79      5   297   1907  1424     129  720     683  3633   3712
2005-10-01    78      4   289   1851  1384     128  708     672  3528   3606
2005-09-01    78      4   286   1817  1365     128  703     669  3472   3550
2005-08-01    78      4   283   1803  1349     128  697     668  3439   3517
2005-07-01    78      4   279   1783  1338     127  690     665  3404   3482
2005-06-01    78      4   275   1768  1318     127  686     660  3365   3443
2005-05-01    77      4   274   1751  1304     125  680     657  3333   3410
2005-04-01    77      4   268   1726  1286     123  667     653  3284   3361
2005-03-01    77      4   263   1686  1260     122  656     649  3213   3290
2005-02-01    77      4   262   1663  1252     121  652     646  3181   3258
2005-01-01    77      4   258   1639  1242     121  645     642  3143   3220
2004-12-01    76      3   249   1607  1221     121  637     634  3080   3156
2004-11-01    76      3   245   1587  1215     120  628     629  3050   3126
2004-10-01    75      3   238   1559  1207     119  617     627  3007   3082
2004-09-01    74      3   230   1521  1182     119  609     626  2936   3010
2004-08-01    74      3   226   1501  1160     118  602     622  2890   2964
2004-07-01    74      3   226   1494  1156     116  599     619  2879   2953
2004-06-01    74      3   223   1464  1143     115  588     616  2833   2907
2004-05-01    74      2   218   1445  1128     115  582     612  2793   2867
2004-04-01    74      2   215   1415  1116     111  572     605  2748   2822
2004-03-01    74      2   206   1379  1098     111  565     596  2685   2759
2004-02-01    73      2   204   1364  1091     110  560     595  2661   2734
2004-01-01    73      2   202   1330  1073     108  550     592  2607   2680
2003-12-01    73      2   196   1298  1061     105  537     584  2557   2630
2003-11-01    73      2   193   1277  1048     105  530     578  2520   2593
2003-10-01    72      2   188   1250  1025     105  522     576  2465   2537
2003-09-01    72      2   185   1229   992     103  513     569  2408   2480
2003-08-01    72      2   185   1217   979     100  508     565  2383   2455
2003-07-01    71      2   184   1210   971     100  505     562  2367   2438
2003-06-01    71      2   182   1194   959     100  500     556  2337   2408
2003-05-01    69      2   180   1180   953      99  498     554  2315   2384
2003-04-01    69      2   175   1160   942      99  491     548  2279   2348
2003-03-01    69      2   170   1141   931      99  484     544  2244   2313
2003-02-01    69      1   169   1121   925      99  479     540  2216   2285
2003-01-01    69      1   167   1094   908      98  469     535  2170   2239
2002-12-01    69      1   163   1067   888      98  467     533  2119   2188
2002-11-01    69      1   160   1052   871      97  461     529  2084   2153
2002-10-01    68      1   158   1028   848      96  455     521  2035   2103
2002-09-01    66      1   155   1007   829      95  449     512  1992   2058
2002-08-01    66      1   154    991   806      93  438     509  1952   2018
2002-07-01    65      1   152    981   799      92  431     504  1933   1998
2002-06-01    65      1   148    962   791      90  422     498  1902   1967
2002-05-01    65      1   144    944   780      89  413     487  1869   1934
2002-04-01    65      1   142    926   767      89  406     485  1836   1901
2002-03-01    64      1   136    899   753      88  396     482  1789   1853
2002-02-01    64      1   131    876   737      87  387     472  1745   1809
2002-01-01    64      1   124    842   714      87  374     465  1681   1745
2001-12-01    64      1   121    806   695      83  360     456  1623   1687
2001-11-01    62      1   120    778   680      82  353     452  1579   1641
2001-10-01    62      1   114    752   657      81  344     448  1524   1586
2001-09-01    62      1   110    723   623      80  333     437  1457   1519
2001-08-01    61      1   109    701   603      80  327     434  1414   1475
2001-07-01    60      1   108    696   590      80  326     433  1395   1455
2001-06-01    59      1   108    686   580      78  323     426  1375   1434
2001-05-01    58      1   107    674   569      76  316     418  1351   1409
2001-04-01    58      1   105    662   560      75  307     414  1328   1386
2001-03-01    58      1   101    647   546      73  298     407  1295   1353
2001-02-01    58      1    98    636   535      72  295     402  1270   1328
2001-01-01    58      1    94    621   526      72  292     398  1242   1300
2000-12-01    58      1    93    607   514      71  286     391  1215   1273
2000-11-01    58      1    90    583   497      70  283     382  1171   1229
2000-10-01    58      1    87    573   483      70  279     375  1144   1202
2000-09-01    58      1    81    555   457      69  272     367  1094   1152
2000-08-01    58      1    79    537   441      67  263     358  1058   1116
2000-07-01    58      1    77    532   431      65  260     347  1041   1099
2000-06-01    58      1    76    527   425      64  256     344  1029   1087
2000-05-01    58      1    76    514   411      64  251     336  1002   1060
2000-04-01    57      1    73    499   398      63  245     329   971   1028
2000-03-01    57      1    64    483   387      61  233     317   935    992
2000-02-01    57      1    62    466   376      61  223     310   905    962
2000-01-01    57      1    57    452   369      61  217     305   879    936
1999-12-01    56      1    56    442   360      59  209     298   859    915
1999-11-01    56      1    54    429   346      59  205     288   830    886
1999-10-01    56      1    54    413   332      58  200     284   800    856
1999-09-01    54      1    54    397   316      56  192     280   768    822
1999-08-01    54      1    54    397   314      56  192     280   766    820
1999-07-01    54      1    54    392   309      55  190     276   756    810
1999-06-01    54      1    51    385   299      55  186     273   736    790
1999-05-01    53      1    49    373   293      51  178     263   716    769
1999-04-01    53      1    48    360   286      50  174     256   695    748
1999-03-01    53      1    47    350   281      50  172     255   679    732
1999-02-01    53      1    47    340   276      50  169     252   664    717
1999-01-01    53      1    45    335   270      50  166     250   651    704
1998-12-01    53      1    41    325   261      50  162     241   628    681
1998-11-01    53      1    38    311   252      48  154     236   602    655
1998-10-01    53      1    36    306   245      48  152     231   588    641
1998-09-01    53      1    29    293   232      47  140     225   555    608
1998-08-01    53      1    29    283   221      45  133     219   534    587
1998-07-01    53      1    29    279   219      43  129     216   528    581
1998-06-01    53      1    29    273   212      42  127     213   515    568
1998-05-01    53      1    29    264   206      42  124     209   500    553
1998-04-01    53      1    27    256   197      42  117     208   481    534
1998-03-01    53      1    27    244   189      42  112     204   461    514
1998-02-01    53      0    26    240   189      41  110     203   455    508
1998-01-01    53      0    26    235   186      41  108     200   447    500
1997-01-01    53      0    22    206   166      39   97     187   394    447
1996-01-01    53      0    20    178   151      37   86     181   349    402
1995-01-01    53      0    19    163   134      36   83     171   316    369
1994-01-01    51      0    15    140   114      32   70     153   269    320
1993-01-01    51      0    13    117    98      30   64     139   228    279
1992-01-01    51      0    11    103    84      28   61     122   198    249
1991-01-01    49      0     9     76    73      23   49     104   158    207
1990-01-01    49      0     8     63    62      20   42      89   133    182
1980-01-01    45      0     3     27    22      12   17      44    52     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    27      0     0      0     1       0    0       1     1     28

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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