Recent Discoveries – Sept 17-24, 2010

Catching up on the last week in comet and asteroid discoveries… A week ago new NEA announcements were coming left and right but the flood completely stopped a few days before Full Moon. Most surveys take a break for a few days around Full Moon since the bright sky is really not conducive for finding much of anything.

Last week saw one and probably two comet discoveries. C/2010 S1 (LINEAR) is a large perihelion (q = 4.4 AU) long-period comet. Currently 17th magnitude and 8.5 AU from the Sun (almost the distance of Saturn), it should brighten to magnitude 12-13 near perihelion in the summer of 2013. This comet marks the 44th (non-SOHO-STEREO) comet discovery of the year and LINEAR’s 199th comet find.

2010 BK118 was first seen back in January by the WISE (Wide Infrared Space Explorer) spacecraft. WISE is conducting a survey of the sky at 4 infrared wavelengths. Though not specifically designed to find asteroids/comets, the spacecraft observes at wavelengths optimal for finding these types of objects. Though not identified as anything special back in January, it was independently rediscovered by LINEAR last week. After a few days of observation, January’s WISE object and this month’s LINEAR object were linked as one and the same. So far there have been no reports of cometary activity even though the orbit is very cometary (long-period type). If it is truly a extinct or dormant comet than it is very large for a comet nucleus at H = 10.2 and a diameter of ~60 km. I’d be very surprised if this object doesn’t turn out to be an actual comet when larger telescopes are pointed its way.

2010 SW3 passed within 0.0058 AU of Earth on Sept. 10. This distance equals 540,000 miles, 860,000 km or 2.1 Lunar Distances. The 10 to 30 meter in diameter rock was discovered by the Mount Lemmon Survey eight days after close approach.

Asteroid    Type     MOID     a     e     i     H  Mag  Discoverer      MPEC
2010 SE12   Amor    0.115   1.36  0.18   9.3  24.3  20  Spacewatch      2010-S34
2010 SD12   Amor    0.076   1.80  0.41  23.6  23.8  20  Mount Lemmon    2010-S33
2010 SA12   Amor    0.147   2.25  0.50   6.2  20.8  20  Mount Lemmon    2010-S32
2010 SX11   Apollo  0.026   1.16  0.25   5.3  24.8  20  Spacewatch      2010-S30
2010 SZ3    Apollo  0.014   1.18  0.14   2.0  28.3  20  Mount Lemmon    2010-S26
2010 SY3    Amor    0.224   2.08  0.41   6.0  22.8  21  Mount Lemmon    2010-S25
2010 SX3    Amor    0.066   1.59  0.33   8.0  24.9  20  Mount Lemmon    2010-S24
2010 SW3    Apollo  0.0005  1.62  0.40   1.6  26.6  20  Mount Lemmon    2010-S23
2010 SV3    Apollo  0.056   1.51  0.52   6.2  20.5  19  Catalina        2010-S21
2010 ST3    Apollo  0.040   2.06  0.53   3.8  25.1  21  PanSTARRS       2010-S20
2010 SS3    Amor    0.393   1.61  0.24  26.9  20.8  21  Mount Lemmon    2010-S19
2010 SR3    Amor    0.187   1.74  0.37  12.2  21.8  21  Mount Lemmon    2010-S18
2010 SP3    Apollo  0.004   1.98  0.63   0.4  24.6  18  Catalina        2010-S16
2010 RG137  Amor    0.105   2.36  0.55   9.9  21.0  19  Mount Lemmon    2010-S15

Comet       Type       T        q     a     e     i  Mag  Period        MPEC 
C/2010 S1 (LINEAR)
            LPC    2013-05-09  4.41       1.0  126.9  17                2010-S41
2010 BK118 (discovered by WISE, rediscovered by LINEAR)
            ECC    2010-01-01  6.12 293.7 0.98 143.9  19  5030          2010-S26

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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