Contents  on 17 December '13

Asteroid/Comet Connection (A/CC) Resources:

The latest A/CC news is available via framed access, RSS news feed RSS news feed, or redirection. - Note: A/CC has a main Web site and also a backup site with its own duplicate RSS news feed.

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 17 December '13

Three objects reported inside ten LD

Three asteroids are reported passing within ten lunar distances (LD) of our planet today. Newly announced 2013 XH22 enters Earth's Hill sphere, flying from 6.78 to 2.90 LD. And the other two depart from our ten-LD reporting "Bubble." Risk-listed intruder 2013 XS21 moves from 8.61 to 10.32 LD and 2013 XU21 from 8.87 to 10.74 LD.

Next "known" to be approaching is returning 2011 YD29, best calculated to arrive inside ten LD on December 23rd, but with an uncertainty of more than 17 hours.

This report was updated at 1952 UTC to note follow-up in today's DOU MPEC for 2013 XU21 and departed 2013 VD17. Today's first report was generated at 0117 UTC to note the discovery of 2013 XH22, announced late yesterday (MPEC), and radar observation of departed 2013 NJ.

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.

Radar Astrometry  on 17 December '13

Radar observation of four objects

The JPL Solar System Dynamics Group Radar Astrometry database has added or updated the following small-body radar observing work:

Data update noted at 0058 UTC when the database was dated 16 Dec.

NEOCP Activity  on 17 December '13

The MPC's NEO Confirmation Page has 18 listings

When last checked at 2320 UTC today, the Minor Planet Center's Near Earth Object discovery Confirmation Page (NEOCP) had eighteen objects listed. Of these, five were "one nighters." So far The Tracking News has counted a total of nineteen listings on the NEOCP today.

New MPECs  on 17 December '13

Minor Planet Electronic Circulars

As of last check at 2320 UTC, there has been one MPEC posted today from the International Astronomical Union's Minor Planet Center in Cambridge, Massachusetts.

<< DOU on 17 Dec. '13 >>  MPEC 2013-Y08 - "14:04 UT" - Daily Orbit Update

Observers  on 17 December '13

Fourteen observers appear in today's MPEC.

CodeObserver / observatory
251Arecibo in Puerto Rico, 4 in radar -- 2013 XZ9, 2013 XG10, 2013 NJ, 2010 CL19
H21Astronomical Research Obs. Westfield in Illinois, 5 in MPEC 2013-Y08 -- 2013 XX8, 2013 XU3, 2013 WW44, 2013 WU44, 2013 VC10
B88Bigmuskie Obs. in Italy, 1 in MPEC 2013-Y08 -- 21088
160Castelmartini Obs. in Italy, 5 in MPEC 2013-Y08 -- 369264, 340666, 294739, 215188, 138095
448Desert Moon Obs. in New Mexico, 5 in MPEC 2013-Y08 -- 2013 TB80, 2008 TQ2, 377732, 376729, 163696
J95Great Shefford Obs. in England, 1 in MPEC 2013-Y08 -- 2013 XU21
844Los Molinos Obs. in Uruguay, 2 in MPEC 2013-Y08 -- 96744, 1036
130Lumezzane Obs. in Italy, 11 in MPEC 2013-Y08 -- 2013 WT45, 2013 VC10, 2013 SK19, 2011 WM2, 2011 CQ4, 2008 WK32, 55532, 363305, 363075, 360433, 6178
5682David Tholen's team on Mauna Kea in Hawaii, 1 in MPEC 2013-Y08 -- 2013 VD17
C91Montevenere Obs., 1 in MPEC 2013-Y08 -- 251346
C23Olmen Obs. in Belgium, 2 in MPEC 2013-Y08 -- 2010 XZ67, 251346
F51Pan-STARRS 1 in Hawaii, 1 in MPEC 2013-Y08 -- 4055
H45Petit Jean Mtn. South Obs. (PJMSO) in Arkansas, 18 in MPEC 2013-Y08 -- 2013 UR3, 2013 TB80, 2011 CQ4, 2010 XZ67, 2010 SL13, 2009 XZ1, 86039, 52760, 378610, 369264, 361071, 340666, 251346, 215188, 162566, 12711, 3200, 1627
233San Vito Obs. in Italy, 5 in MPEC 2013-Y08 -- 251346, 21088, 162566, 12711, 1627
For a list of all participating observatories that have Web addresses, see A/CC's Observatory Links page.

Impact Risk Monitoring  on 17 December '13

Summary Risk Table for Risk Assessments Updated Today   (last checks: NEODyS and JPL at 2320 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 XK22NEODyS15462042-2112491.46e-05-4.36-4.410NEODyS: "Based on 39 optical observations (of which 5 are rejected as outliers) from 2013-12-14.432 to 2013-12-16.143."
JPL Sentry05102042-2105447.6e-06-4.84-5.380JPL: "Analysis based on 35 observations spanning 1.7111 days (2013-Dec-14.43128 to 2013-Dec-16.14243)." Diameter approximately 0.052 km. from mean, weighted H=24.1.
2013 VD17JPL Sentry16052065-207527.0e-07-7.25-7.310JPL: "Analysis based on 25 observations spanning 26.293 days (2013-Nov-14.24215 to 2013-Dec-10.53514)." Diameter approximately 0.013 km. from mean, weighted H=27.1.
NEODyS15462075-207515.0e-08-8.40-8.40NEODyS: "Based on 26 optical observations (of which 1 are rejected as outliers) from 2013-11-14.243 to 2013-12-10.536."

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 17 December '13

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

1952Updated Traffic Report
1605Noted that JPL Sentry has updated its 2013 VD17 risk assessment - see above
1546Noted that NEODyS has updated its 2013 VD17 risk assessment - see above
Noted that NEODyS has posted 2013 XK22 as an impact risk - see above
Grabbed MPEC 2013-Y08 - Daily Orbit Update - see above
0510Noted that JPL Sentry has posted 2013 XK22 as an impact risk - see above
0058Noted Radar Astrometry database update - see above