Contents  on 21 December '12

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 21 December '12

Three objects reported inside ten LD

Three asteroids are reported traveling inside ten lunar distances (LD) of our planet today. Within Earth's Hill sphere, radar target 2012 XM55 is inbound from 3.54 to 3.26 LD. More distantly, radar target intruder 2012 XB112 is outbound from 6.10 to 7.04 LD and newly discovered risk-listed 2012 YR1 is also headed out, moving from 6.58 to 7.65 LD.

Approaching our neighborhood next, newly announced 2012 YS1 arrives inside ten LD on December 23rd and 2012 XP55 arrives on December 26th.

This report was generated at 1821 UTC with new discoveries 2012 YS1 (MPEC) and 2012 YR1 (MPEC) and follow-up in today's DOU MPEC for departed objects 2012 XK134, 2012 XP2, and 2012 XH.

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 21 December '12

The MPC's NEO Confirmation Page has 22 listings

When last checked at 2359 UTC today, the Minor Planet Center's Near Earth Object discovery Confirmation Page (NEOCP) had 22 objects listed. Of these, seventeen were "one nighters." So far The Tracking News has counted a total of 26 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 21 December '12

Minor Planet Electronic Circulars

As of last check at 2359 UTC, there have been five MPECs posted today from the International Astronomical Union's Minor Planet Center in Cambridge, Massachusetts.

MPEC 2012-Y17 - "15:47 UT" - 2012 YS1

MPEC 2012-Y16 - "15:44 UT" - 2012 YR1

MPEC 2012-Y15 - "15:41 UT" - 2012 YQ1

MPEC 2012-Y14 - "15:25 UT" - 2011 AG5

<< DOU on 21 Dec. '12 >>  MPEC 2012-Y13 - "06:04 UT" - Daily Orbit Update

Observers  on 21 December '12

Thirteen observers appear in today's MPECs.

CodeObserver / observatory
300Bisei Spaceguard Center in Japan, 1 in MPEC 2012-Y15 -- 2012 YQ1
703Catalina Sky Survey (CSS) in Arizona, 14 in MPECs 2012-Y13 & 2012-Y17 -- 2012 YS1, 2012 XC112, 2012 VF37, 2002 NP1, 85490, 329614, 329338, 249886, 17188, 137199, 137044, 4486, 3360, 3199
106Crni Vrh Obs. in Slovenia, 1 in MPEC 2012-Y13 -- 2007 YX1
448Desert Moon Obs. in New Mexico, 3 in MPEC 2012-Y13 -- 2010 XL69, 345646, 338172
G32Elena Remote Obs., 1 in MPEC 2012-Y15 -- 2012 YQ1
E89Geyserland Obs. in New Zealand, 2 in MPEC 2012-Y13 -- 138937, 4179
H15ISON-NM Obs. in New Mexico, 1 in MPEC 2012-Y15 -- 2012 YQ1
704LINEAR in New Mexico, 9 in MPECs 2012-Y13, 2012-Y15 & 2012-Y16 -- 2012 YR1, 2012 YQ1, 2012 XY6, 2012 SA59, 2000 WL63, 345722, 153243, 141052, 138859
H01Magdalena Ridge Obs. (MRO) in New Mexico, 3 in MPECs 2012-Y15, 2012-Y16 & 2012-Y17 -- 2012 YS1, 2012 YR1, 2012 YQ1
5682David Tholen's team on Mauna Kea in Hawaii, 2 in MPECs 2012-Y13 & 2012-Y14 -- 2012 VC82, 2011 AG5
854Sabino Canyon Obs. in Arizona, 2 in MPECs 2012-Y15 & 2012-Y17 -- 2012 YS1, 2012 YQ1
H36Sandlot Obs. in Kansas, 2 in MPECs 2012-Y16 & 2012-Y17 -- 2012 YS1, 2012 YR1
291Spacewatch 1.8m telescope in Arizona, 15 in MPECs 2012-Y13, 2012-Y15 & 2012-Y17 -- 2012 YS1, 2012 YQ1, 2012 XS93, 2012 XS134, 2012 XS111, 2012 XR111, 2012 XP2, 2012 XK134, 2012 XH16, 2012 XH133, 2012 XH, 2012 XG55, 2012 XD112, 2012 VG6, 2012 UZ33
For a list of all participating observatories that have Web addresses, see A/CC's Observatory Links page.

Impact Risk Monitoring  on 21 December '12

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
2012 YR1NEODyS22202038-2099103.62e-05-5.43-5.590NEODyS: "Based on 11 optical observations (of which 0 are rejected as outliers) from 2012-12-20.210 to 2012-12-21.319."
JPL Sentry18082035-2105133.2e-05-5.48-5.680JPL: "Analysis based on 11 observations spanning 1.1089 days (2012-Dec-20.20945 to 2012-Dec-21.31831)." Diameter approximately 0.017 km. from mean, weighted H=26.5.
2012 YQ1JPL Sentry1808210612.6e-07-4.88-4.880JPL: "Analysis based on 32 observations spanning 2.1219 days (2012-Dec-19.23613 to 2012-Dec-21.35806)." Diameter approximately 0.220 km. from mean, weighted H=20.9.
2012 XK134NEODyS16422091-209114.97e-09-9.36-9.360NEODyS: "Based on 34 optical observations (of which 0 are rejected as outliers) from 2012-12-13.147 to 2012-12-20.356."
JPL Sentry1642R E M O V E DJPL: Risk listing removed at 0954 UTC.
2012 XHJPL Sentry16422103-211021.3e-07-7.84-8.130JPL: "Analysis based on 39 observations spanning 17.205 days (2012-Dec-03.17776 to 2012-Dec-20.38254)." Diameter approximately 0.021 km. from mean, weighted H=26.1.
NEODyS16422072-208433.67e-08-8.24-8.510NEODyS: "Based on 39 optical observations (of which 0 are rejected as outliers) from 2012-12-03.179 to 2012-12-20.383."
2011 AG5NEODyS2220R E M O V E D-
JPL Sentry1955R E M O V E DJPL: Risk listing removed at 1941 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 21 December '12

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

2220Noted that NEODyS has removed 2011 AG5 as an impact risk - see above
Noted that NEODyS has posted 2012 YR1 as an impact risk - see above
1955Noted that JPL Sentry has removed 2011 AG5 as an impact risk - see above
1821Generated Traffic Report
1808Noted that JPL Sentry has posted 2012 YQ1 as an impact risk - see above
Noted that JPL Sentry has posted 2012 YR1 as an impact risk - see above
1642Noted that JPL Sentry has reposted 2012 XH as an impact risk - see above
Noted that NEODyS has updated its 2012 XH risk assessment - see above
Noted that JPL Sentry has removed 2012 XK134 as an impact risk - see above
Noted that NEODyS has updated its 2012 XK134 risk assessment - see above
Grabbed MPEC 2012-Y13 - Daily Orbit Update - see above
Grabbed MPEC 2012-Y14 - 2011 AG5 - see above
Grabbed MPEC 2012-Y15 - 2012 YQ1 - see above
Grabbed MPEC 2012-Y16 - 2012 YR1 - see above
Grabbed MPEC 2012-Y17 - 2012 YS1 - see above