Recent Discoveries – Oct 12 to 18

2010 TW54 is the first of 4 small asteroids to buzz the Earth in the past week. I should rephrase that last sentence and say it is the first of 4 small asteroids that we know buzzed the Earth last week. For every small one we see, many hundreds pass by unseen. Luckily they are all too small to do anything more than cause a nice fireball light show and drop a few meteorites. Back to TW54, it passed within 0.0011 AU (102,000 miles / 163,000 km / 0.42 lunar distances) of Earth on October 9. At that time it had brightened to 14th magnitude though it would not be discovered for another 2 days.

2010 TN55 got up to 16th magnitude during its close approach to Earth on October 11. At its closest, this 7 to 24 meter across asteroid passed 0.0022 AU from Earth (or 205,000 miles / 327,000 km / 0.85 lunar distances). Having been found by Spacewatch , this is the only one of the 4 recent close approachers not found by the Mount Lemmon Survey

2010 UE flew past the Earth on October 16 at a close distance of 0.00073 AU. That works out to only 68,000 miles or 109,000 km or 0.28 lunar distances. Like most close calls this object is very small (2 to 7 meters across) and would never have survived passage through Earth’s atmosphere to reach the ground as anything more than a bunch of small meteorites.

2010 UJ is a yet another small asteroid (size between 10 and 40 meters across). Residing on an orbit that is not too different from Earth’s, this asteroid may make a good target for future manned and/or unmanned spacecraft missions. That is unless it gets lost which is common for such a small object that can not be observed except when very close to Earth. UJ will pass within 0.04 AU of Earth on Nov. 1 when it will shine at a faint magnitude of 19.9.

2010 UK passed 0.0056 AU (520,000 miles / 830,000 km / 2.2 lunar distances) from Earth on October 16. UK is between 10 and 30 meters across.

Three new Jupiter-family comets were found including the first comet discovered by the PANSTARRS survey. The other 2 were found by Catalina/Mount Lemmon observers Andrea Boattini and Rik Hill. This is Andrea’s 4th comet discovery of the year and 15th overall. For Rik, this is also his 4th of the year and 23rd overall.

P/2010 T2 (PANSTARRS) is a faint comet at ~20th magnitude. Even at perihelion next summer at a distant 3.73 AU it will only brighten to magnitude 19.5. This comet is a short-period Jupiter-family comet with a period of 13.2 years.

P/2010 U1 (Boattini) is a few months past perihelion. Right now it is at its brightest which is still a very faint 19th magnitude. With perihelion at 4.88 AU, this comet only comes a little closer than the orbit of Jupiter. This comet does not travel as far from the Sun as Saturn and its motion is dominated by Jupiter. Hence this is another short-period Jupiter-family comet. It orbits the Sun once every 17.2 years.

P/2010 U2 (Hill) is also a short-period Jupiter-family comet with a period of 8.88 years. Perihelion occurs next month at a distance of 2.56 AU. Its current brightness of 18th magnitude is as bright as this comet will get.

Asteroid   Type   Mag    MOID     a     e     i     H   Discoverer      MPEC
2010 UK    Aten    16   0.002   0.87  0.21   4.9  26.8  Mount Lemmon    2010-U17
2010 UJ    Aten    20   0.003   0.94  0.09   0.4  26.2  Mount Lemmon    2010-U16
2010 UH    Apollo  20   0.003   1.36  0.31   0.7  27.1  Mount Lemmon    2010-U15
2010 UG    Apollo  20   0.038   1.51  0.34   8.0  25.4  Mount Lemmon    2010-U14
2010 UE    Apollo  19   0.0003  2.63  0.71   3.1  29.6  Mount Lemmon    2010-U12
2010 UD    Apollo  15   0.014   1.10  0.26  26.3  21.3  Mount Lemmon    2010-U11
2010 UC    Aten    17   0.007   0.94  0.07   4.7  27.4  Catalina        2010-U10
2010 UB    Apollo  19   0.010   2.06  0.52   3.4  24.3  LINEAR          2010-U08
2010 UN167 Apollo  21   0.009   1.70  0.59   5.4  27.1  Mount Lemmon    2010-U06
2010 TM167 Apollo  21   0.085   1.16  0.48   5.1  20.9  Mount Lemmon    2010-U05
2010 TL167 Aten    21   0.114   0.97  0.64  12.5  22.4  Mount Lemmon    2010-U04
2010 TK167 Apollo  19   0.065   3.20  0.69  18.6  22.8  LINEAR          2010-U03
2010 TJ167 Amor    20   0.259   2.22  0.44   4.7  21.1  Mount Lemmon    2010-U02
2010 TS149 Apollo  20   0.027   1.50  0.39   3.4  19.8  Mount Lemmon    2010-118
2010 TS55  Amor    21   0.145   1.15  0.46   6.0  24.2  Mount Lemmon    2010-T117
2010 TR55  Amor    18   0.234   2.61  0.53  21.8  18.7  Catalina        2010-T116
2010 TP55  Apollo  21   0.002   2.06  0.62   3.1  20.4  PANSTARRS       2010-T115
2010 TO55  Apollo  17   0.006   1.68  0.41   4.8  26.5  Catalina        2010-T113
2010 TN55  Apollo  20   0.002   2.15  0.77   0.4  27.1  Spacewatch      2010-T112
2010 TL55  Apollo  21   0.120   2.45  0.64  29.6  19.0  Spacewatch      2010-T111
2010 TK55  Apollo  19   0.058   1.06  0.07  24.0  23.8  LINEAR          2010-T110
2010 TF55  Amor    20   0.118   2.63  0.58  12.9  24.0  Mount Lemmon    2010-T106
2010 TE55  Aten    18   0.002   0.93  0.13   1.9  28.1  Mount Lemmon    2010-T105
2010 TD55  Apollo  19   0.073   1.46  0.36  23.3  23.3  LINEAR          2010-T104
2010 TC55  Amor    18   0.121   2.78  0.61  19.7  19.9  Maticic&Zakrajsek010-T103
2010 TA55  Amor    21   0.194   1.52  0.25  15.5  21.9  PANSTARRS       2010-T102
2010 TZ54  Amor    20   0.304   2.29  0.45   9.5  19.0  Spacewatch      2010-T101
2010 TY54  Amor    19   0.218   2.40  0.50   8.7  21.3  Mount Lemmon    2010-T100
2010 TX54  Apollo  19   0.107   1.45  0.34  27.1  20.9  Catalina        2010-T89
2010 TW54  Apollo  18   0.0013  1.05  0.24   2.7  27.6  Mount Lemmon    2010-T88
2010 TV54  Apollo  20   0.007   1.93  0.62   6.2  25.5  Mount Lemmon    2010-T87
2010 TU54  Amor    21   0.263   1.57  0.33  27.4  21.3  PANSTARRS       2010-T86
2010 TS54  Amor    21   0.130   1.46  0.23  15.3  24.5  Mount Lemmon    2010-T85
2010 TR54  Amor    20   0.072   1.70  0.37   4.4  24.5  Mount Lemmon    2010-T84
2010 RS180 Amor    19   0.110   1.88  0.41   2.9  20.5  La Sagra        2010-T109

Comet       Type       T        q     a     e      i  Mag  Period        MPEC 
P/2010 U2 (Hill)
            JFC   2010 11 09  2.55  4.29  0.40   16.9  18   8.88 yrs     2010-U19
P/2010 U1 (Boattini)
            JFC   2010 05 15  4.88  6.66  0.27    8.2  19  17.2  yrs     2010-U18
P/2010 T2 (PANSTARRS)
            JFC   2011 07 29  3.73  5.59  0.33    8.1  21  13.2  yrs     2010-U07

Type
Aten -  Earth crossing with semi-major axis (avg distance from Sun) < 1 AU
Apollo - Earth crossing with semi-major axis (avg distance from Sun) > 1 AU
Amor - non-Earth crossing with perihelion distance < 1.3 AU
JFC - Jupiter family comet
HFC - Halley family comet
LPC - Long-period comet
MBC - Main belt comet
ECC - Suspected extinct or dormant (or just unrecognized) comet
T - Date of Perihelion
MOID - Minimum Orbit Intercept Distance, minimum distance between asteroid and Earth's orbit
a - semi-major axis, average distance from Sun in AU (1 AU = 93 million miles)
e - eccentricity
i - inclination
H - absolute magnitude
Mag - magnitude at discovery
Discoverer - survey or person who discovered the object
MPEC - Minor Planet Electronic Circular, the discovery announcement
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