Contents  on 24 December '18

Asteroid/Comet Connection (A/CC) Resources:

The latest A/CC news is available via framed access, RSS news feed RSS news feed, or redirection.

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. To keep track of what's new each day, watch the Chronology section.

Traffic Report  on 24 December '18

Seven objects reported inside ten LD

Seven Solar-System small bodies are reported inside ten lunar distances (LD) of our home world today. Nearest is risk-listed 2018 XN5, which comes its closest to Earth on this passage, reaching 2.96 LD at 1816 UTC.

Neighborhood Traffic - sorted by Earth passage distance, grouped by 1.0, 2.41, 5.0 & 10.0 LD boundaries
Earth passage I D ~Size Distance today  Inside ten LD Notes
0.09 LD Dec. 2 2018 WV1 3 m  9.35 to 9.77 LD Nov. 8 - tomorrow intruder, NHATS target
1.60 LD Dec. 21 2018 XC4 20 m  4.38 to 6.03 LD Dec. 15 - 27 NHATS target
2.62 LD Dec. 15 2018 VO9 14 m  5.96 to 6.52 LD Nov. 29 - Dec. 31 NHATS target, risk
2.96 LD today 2018 XN5 28 m  2.96 LD Dec. 18 - 31 NHATS target, Earth closest at 1816 UTC, risk
3.92 LD Dec. 2 2018 TG6 12 m  7.14 to 7.38 LD Oct. 30 - Jan. 5 NHATS target
5.3   LD Dec. 26* 2018 XE4 17 m  6.6 from 8.0 LD Dec. 22 - 30 EPU +/- 3.33 hours*
7.36 LD Dec. 22 163899 2003 SD220 1.17 km  7.86 to 8.46 LD Dec. 17 - 26 radar/NHATS target
* EPU = Earth passage uncertainty

This report was generated at 1840 UTC with follow-up in today's DOU MPEC for three departed risk-listed objects: 2018 XW3, 2018 XQ2, and 2018 XA, plus distant 68216 2001 CV26.

Approaching - sorted by 10-LD bubble entry date
Earth passage I D ~Size Distance today  Inside ten LD Notes
7.8   LD Jan. 6* 2018 XO4 29 m  13.8 from 14.5 LD Dec. 30 - Jan. 13 EPU +/- 3.18 hours*, NHATS target
7.3   LD Jan. 9* 2013 YM2 19 m  16.7 from 17.6 LD Jan. 2 - 16 EPU +/- 3.75 days*, NHATS target

<< Reading:  The American Meteor Society has a report about a bright fireball over northern California early on December 19th local time, and Wired has an article about the world of meteorite hunters and the "mad scramble" to recover pieces from a 2007 South American meteor impact.

Notes: Ten times the distance to the Moon (ten LD) has no astronomical importance but is a useful boundary for reporting about transient natural objects that approach our planet's gravitational sphere of influence (SOI), which has a radius of about 2.41 LD from Earth's center. This puts a focus on some of the most important and very best NEO observation work, representative of the much larger NEO discovery and tracking effort. "Distant" is used here to describe an object that has approached Earth within ten LD since A/CC began these traffic reports eleven-plus years ago but is not currently coming so close. Object temporal distances are derived by A/CC from JPL Horizons data. "LD*" indicates some uncertainty in object passage time and distance. See also current sky chart and object details (alt-details), ephemerides, and today's timeline.

NEOCP Activity  on 24 December '18

The MPC's NEO Confirmation Page has 28 listings

When last checked at 2324 UTC today, the Minor Planet Center's Near Earth Object discovery Confirmation Page (NEOCP) had 28 objects listed. Of these, eighteen 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 24 December '18

Minor Planet Electronic Circulars

As of last check at 2324 UTC, there have been three MPECs posted today from the International Astronomical Union's Minor Planet Center in Cambridge, Massachusetts.

MPEC 2018-Y65 - "15:20 UT" - 2018 YZ1

MPEC 2018-Y64 - "15:14 UT" - 2018 XN17

<< DOU on 24 Dec. '18 >>  MPEC 2018-Y63 - "13:07 UT" - Daily Orbit Update

Observers  on 24 December '18

Twelve observers appear in today's MPECs.

CodeObserver / observatory
H21Astronomical Research Obs. Westfield in Illinois, 6 in MPEC 2018-Y63 -- 2018 XW2, 2018 XN4, 2018 VH2, 2018 NR, 2014 XX31, 2014 AY28
T08ATLAS Mauna Loa in Hawaii, 2 in MPEC 2018-Y63 -- 2014 JU54, 2010 GT7
160Castelmartini Obs. in Italy, 6 in MPEC 2018-Y63 -- 68216, 36284, 345722, 345705, 217807, 154656
V06Catalina Sky Survey Kuiper Telescope in Arizona, 1 in MPEC 2018-Y64 -- 2018 XN17
695^Spacewatch via Kitt Peak Natl. Obs. (KPNO) in Arizona, 9 in MPECs 2018-Y63, 2018-Y64 & 2018-Y65 -- 2018 YZ1, 2018 YJ, 2018 XY3, 2018 XW3, 2018 XQ2, 2018 XN17, 2018 XA, 2018 TO6, 2014 OM339
568^R. Wainscoat on Mauna Kea in Hawaii, 1 in MPEC 2018-Y64 -- 2018 XN17
G96Mt. Lemmon Survey in Arizona, 1 in MPEC 2018-Y63 -- 2010 GT7
I41Palomar Transient Factory in southern California, 1 in MPEC 2018-Y63 -- 523610
F51Pan-STARRS 1 (PS1) in Hawaii, 6 in MPECs 2018-Y63, 2018-Y64 & 2018-Y65 -- 2018 YZ1, 2018 XZ2, 2018 XN17, 512245, 483472, 3200
F52Pan-STARRS 2 in Hawaii, 1 in MPEC 2018-Y63 -- 2010 GT7
C95SATINO-1 in France, 1 in MPEC 2018-Y63 -- 2012 MS4
Q21Southern Utsunomiya in Japan, 1 in MPEC 2018-Y63 -- 3200
For a list of all participating observatories that have Web addresses, see A/CC's Observatory Links page.

Impact Risk Monitoring  on 24 December '18

Summary Risk Table for Risk Assessments Updated Today   (last checks: NEODyS at 2324 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 and NEODyS listings is 100 years, and both post impact solutions beyond that for some special objects.
For the latest official risk assessments, and for explanations of the terminology, see the NASA/JPL Sentry and NEODyS CLOMON2 risk pages.





Notes for Today's Latest Risk Assessments
2018 YZ1JPL Sentry16402034-211889.0796e-09-4.85-5.130JPL: Computed at 08:28 today Pacific time based on 13 observations spanning 3.8103 days (2018-Dec-20.63258 to 2018-Dec-24.44283). Diameter approximately 0.695 km. from weighted mean H=18.45.
2018 YJNEODyS23012038-208333.26e-09-5.22-5.260NEODyS: "Based on 33 optical observations (of which 0 are rejected as outliers) from 2018-12-16.536 to 2018-12-24.482."
JPL Sentry16402050-208322.941e-09-5.34-5.410JPL: Computed at 08:30 today Pacific time based on 33 observations spanning 7.9464 days (2018-Dec-16.5351 to 2018-Dec-24.48152). Diameter approximately 0.719 km. from weighted mean H=18.36.
2018 XW3NEODyS23012030-204457.88e-07-6.31-6.630NEODyS: "Based on 23 optical observations (of which 0 are rejected as outliers) from 2018-12-13.230 to 2018-12-24.222."
JPL Sentry16402030-204443.17889e-07-6.81-6.920JPL: Computed at 08:32 today Pacific time based on 23 observations spanning 10.992 days (2018-Dec-13.2296 to 2018-Dec-24.22121). Diameter approximately 0.019 km. from weighted mean H=26.30.
2018 XQ2NEODyS23012053-21181716.62e-04-5.09-5.73-NEODyS: "Based on 35 optical observations (of which 0 are rejected as outliers) from 2018-12-10.243 to 2018-12-24.144."
JPL Sentry17032053-2117680.0006570411619-5.09-5.610JPL: Computed at 08:47 today Pacific time based on 35 observations spanning 13.901 days (2018-Dec-10.2423 to 2018-Dec-24.14284). Diameter approximately 0.008 km. from weighted mean H=28.14.
2018 XANEODyS2301209924.19e-09-7.88-8.090NEODyS: "Based on 144 optical observations (of which 3 are rejected as outliers) from 2018-12-01.348 to 2018-12-24.376."
JPL Sentry16402099-209921.3719e-08-7.35-7.530JPL: Computed at 08:29 today Pacific time based on 142 observations spanning 23.028 days (2018-Dec-01.34686 to 2018-Dec-24.37514). Diameter approximately 0.063 km. from weighted mean H=23.64.
2013 YBJPL Sentry16402022-2063267.46111574e-05-6.59-7.020JPL: Computed at 08:53 April 8th of 2017 Pacific time based on 11 observations spanning .16022 days (2013-Dec-23.21048 to 2013-Dec-23.3707). Diameter approximately 0.002 km. from weighted mean H=31.44.

Legend: VI# = VI count, Prob Cum = cumulative probability, PS Cum/Max = cumulative/maximum Palermo Scale, TS = Torino Scale (next 100 years)

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 24 December '18

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

2301Noted that NEODyS has updated its 2018 XA risk assessment - see above
Noted that NEODyS has updated its 2018 XQ2 risk assessment - see above
Noted that NEODyS has updated its 2018 XW3 risk assessment - see above
Noted that NEODyS has updated its 2018 YJ risk assessment - see above
1840Generated Traffic Report
1703Noted that JPL Sentry has updated its 2018 XQ2 risk assessment - see above
1640Noted that JPL Sentry has updated its 2013 YB risk assessment - see above
Noted that JPL Sentry has updated its 2018 XA risk assessment - see above
Noted that JPL Sentry has updated its 2018 XW3 risk assessment - see above
Noted that JPL Sentry has updated its 2018 YJ risk assessment - see above
Noted that JPL Sentry has posted 2018 YZ1 as an impact risk - see above
Grabbed MPEC 2018-Y63 - Daily Orbit Update - see above
Grabbed MPEC 2018-Y64 - 2018 XN17 - see above
Grabbed MPEC 2018-Y65 - 2018 YZ1 - see above