Contents  on 14 December '13

Asteroid/Comet Connection (A/CC) Resources:

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Navigation tips: Use the << and >> arrows on the menus for each regular section (Observers, Risks, etc.) to move to the previous and next day's news for that section. Use the Index menu item to access specific days through a calendar interface. And use the all-up news archive to access news from any time since A/CC began in early 2002. To keep track of what's new each day, watch the Chronology section.

Traffic Report  on 14 December '13

Five objects reported inside ten LD

Five visitors are reported to be within ten lunar distances (LD) of our home world today. Newly announced risk-listed intruder 2013 XS21 exits Earth's Hill sphere, flying from 3.50 to 5.20 LD, after passing Earth at 0.19 LD on December 11th. Out further, radar target 2013 XY8 is headed away from 5.50 to 7.42 LD, newly discovered risk-listed 2013 XU21 comes its closest to Earth this time around, reaching 6.16 LD at 0819 UT, new discovery 2013 XT21 heads out from 6.20 to 9.20 LD, and 2013 XH17 departs from inside ten LD, moving from 9.83 to 11.52 LD.

This report was generated at 1807 UTC with new discoveries 2013 XU21 (MPEC), 2013 XT21 (MPEC), and 2013 XS21 (MPEC), and follow-up in today's DOU MPEC for 2013 XH17. We also note radar observation of 2013 XY8 posted yesterday

Notes: Ten times the distance to the Moon (ten LD) has no astronomical significance but is a useful reporting boundary. Earth's Hill sphere (of gravitational influence) is estimated to extend out to around 3.89 LD. Object distances are interpreted by A/CC from JPL Horizons data. See also current sky chart and object details (alt-details), ephemerides, and today's timeline.

NEOCP Activity  on 14 December '13

The MPC's NEO Confirmation Page has 19 listings

When last checked at 2358 UTC today, the Minor Planet Center's Near Earth Object discovery Confirmation Page (NEOCP) had nineteen objects listed. Of these, six were "one nighters." So far The Tracking News has counted a total of 38 listings on the NEOCP today.

To learn how observers use the NEOCP, see the Practical guide on how to observe NEOCP object at Suno Observatory by Birtwhistle et al.

New MPECs  on 14 December '13

Minor Planet Electronic Circulars

As of last check at 2358 UTC, there have been seven MPECs posted today from the International Astronomical Union's Minor Planet Center in Cambridge, Massachusetts.

MPEC 2013-X72 - "19:16 UT" - Comet P/2008 A2 = 2013 X2 (LINEAR)

MPEC 2013-X71 - "18:31 UT" - 2012 TT

<< DOU on 14 Dec. '13 >>  MPEC 2013-X70 - "14:03 UT" - Daily Orbit Update

MPEC 2013-X69 - "12:42 UT" - 2013 XU21

MPEC 2013-X68 - "12:33 UT" - 2013 XT21

MPEC 2013-X67 - "12:26 UT" - 2013 XS21

MPEC 2013-X66 - "02:23 UT" - 2007 UW1

Observers  on 14 December '13

Fifteen observers appear in today's MPECs.

CodeObserver / observatory
H21Astronomical Research Obs. Westfield in Illinois, 6 in MPECs 2013-X67, 2013-X68, 2013-X69 & 2013-X70 -- 2013 XU21, 2013 XT21, 2013 XS21, 163696, 2212, 1627
703Catalina Sky Survey (CSS) in Arizona, 14 in MPECs 2013-X67, 2013-X68, 2013-X69 & 2013-X70 -- 2013 XU21, 2013 XT21, 2013 XS21, 2013 TH5, 2010 SL13, 2009 WZ104, 2008 TQ2, 2006 CT, 89355, 35432, 262623, 163679, 2212, 1943
807|Robert Holmes in Illinois via Cerro Tololo Inter-American Obs. (CTIO) in Chile, 9 in MPEC 2013-X70 -- 2013 XY9, 2013 WT44, 2004 YR, 2003 XB22, 2000 AG205, 377732, 374855, 366733, 363790
958Dax Obs. in France, 1 in MPEC 2013-X69 -- 2013 XU21
639Dresden Obs. in Germany, 1 in MPEC 2013-X70 -- 215188
J95Great Shefford Obs. in England, 2 in MPECs 2013-X67 & 2013-X68 -- 2013 XT21, 2013 XS21
844Los Molinos Obs. in Uruguay, 5 in MPEC 2013-X70 -- 2013 UH9, 96744, 142781, 1980, 1943
A06Mataro Obs. in Spain, 2 in MPEC 2013-X70 -- 9950, 3200
5682David Tholen's team on Mauna Kea in Hawaii, 1 in MPEC 2013-X66 -- 2007 UW1
G96Mt. Lemmon Survey (MLS) in Arizona, 6 in MPECs 2013-X67, 2013-X68, 2013-X69 & 2013-X70 -- 2013 XU21, 2013 XT21, 2013 XS21, 2002 VR94, 55532, 168378
566NEAT's GEODSS Haleakala telescope in Hawaii, 1 in MPEC 2013-X70 -- 2013 TH5
C23Olmen Obs. in Belgium, 2 in MPEC 2013-X70 -- 2010 XZ67, 251346
691Spacewatch 0.9m telescope in Arizona, 1 in MPEC 2013-X70 -- 2013 WT45
926Tenagra II Obs. in Arizona, 11 in MPECs 2013-X68, 2013-X70 & 2013-X71 -- 2013 XZ9, 2013 XZ20, 2013 XY9, 2013 XY20, 2013 XT21, 2013 XH17, 2013 XG10, 2013 XA21, 2013 WU45, 2013 VV4, 2012 TT
H06|Hidetaka Sato in Japan via iTelescope Obs. Mayhill in New Mexico, 1 in MPEC 2013-X72 -- P/2013 X2
For a list of all participating observatories that have Web addresses, see A/CC's Observatory Links page.

Impact Risk Monitoring  on 14 December '13

Summary Risk Table for Risk Assessments Updated Today   (last checks: NEODyS and JPL at 2359 UTC)
See the CRT page for a list of all objects rated recently as risks and our ephemerides page for a list of risk-listed objects under current observation.
The time horizon for JPL is 100 years from today and for NEODyS is usually the year 2090. Both also post impact solutions beyond 100 years for a few special objects.
For the latest official risk assessments, and for explanations of the terminology, see the JPL NEO Program Sentry and NEODyS CLOMON2 risk pages.





Notes for Today's Latest Risk Assessments
2013 XU21NEODyS16112055-206624.04e-08-7.95-8.190NEODyS: "Based on 35 optical observations (of which 8 are rejected as outliers) from 2013-12-13.248 to 2013-12-14.411."
2013 XS21JPL Sentry16112079-211192.7e-06-8.04-8.380JPL: "Analysis based on 24 observations spanning 1.6583 days (2013-Dec-12.48055 to 2013-Dec-14.13884)." Diameter approximately 0.004 km. from mean, weighted H=29.4.
NEODyS16112071-2111103.2e-06-7.99-8.470NEODyS: "Based on 25 optical observations (of which 2 are rejected as outliers) from 2013-12-12.481 to 2013-12-14.140."
2010 XCJPL Sentry05392015-21101561.4e-06-7.68-8.160JPL: "Analysis based on 8 observations spanning .05836 days (2010-Dec-01.30659 to 2010-Dec-01.36495)." Diameter approximately 0.005 km. from mean, weighted H=29.0.
2007 UW1NEODyS1611R E M O V E D-
JPL Sentry0539R E M O V E DJPL: Risk listing removed at 0419 UTC.

Legend: VI# = VI count, Prob Cum = cumulative probability, PS Cum/Max = cumulative/maximum Palermo Scale, TS = Torino Scale

An impact solution, also known as a "virtual impactor" (VI), is not a prediction but rather a possibility derived from a variant orbit calculation that cannot be eliminated yet based on the existing data. Elimination can come quickly with just a little further observation or may take weeks or months, sometimes years. Once superceded or eliminated, a former impact solution has zero relevance to an object's risk. See Jon Giorgini's "Understanding Risk Pages" to learn more.

Chronology  on 14 December '13

Times are UTC for when items were noted or added by The Tracking News.

2235Grabbed MPEC 2013-X72 - Comet P/2008 A2 = 2013 X2 (LINEAR) - see above
1927Grabbed MPEC 2013-X71 - 2012 TT - see above
1807Generated Traffic Report
1611Noted that NEODyS has removed 2007 UW1 as an impact risk - see above
Noted that JPL Sentry has posted 2013 XS21 as an impact risk - see above
Noted that NEODyS has posted 2013 XS21 as an impact risk - see above
Noted that NEODyS has posted 2013 XU21 as an impact risk - see above
Grabbed MPEC 2013-X67 - 2013 XS21 - see above
Grabbed MPEC 2013-X68 - 2013 XT21 - see above
Grabbed MPEC 2013-X69 - 2013 XU21 - see above
Grabbed MPEC 2013-X70 - Daily Orbit Update - see above
0539Noted that JPL Sentry has removed 2007 UW1 as an impact risk - see above
Noted that JPL Sentry has updated its 2010 XC risk assessment - see above
0245Grabbed MPEC 2013-X66 - 2007 UW1 - see above