Contents  on 31 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 31 December '18

Six objects reported inside ten LD

There are six transient natural objects reported inside ten lunar distances (LD) of Earth today. Nearest is 2018 YM2, which comes its closest to our planet on this passage -- 6.41 LD at 0108 UTC.

Neighborhood Traffic - sorted by Earth passage distance, grouped by 1.0, 5.0 & 10.0 LD boundaries
Earth passage I D ~Size Distance today  Inside ten LD Notes
0.15 LD Dec. 27 2018 YL2 5 m  8.36 to 10.92 LD Dec. 23 - 31 intruder, exits ten LD, risk
2.62 LD Dec. 15 2018 VO9 14 m  9.96 to 10.53 LD Nov. 29 - today NHATS target, exits ten LD, risk
2.96 LD Dec. 24 2018 XN5 28 m  9.33 to 10.68 LD Dec. 18 - 31 NHATS target, exits ten LD, risk
3.92 LD Dec. 2 2018 TG6 12 m  8.81 to 9.05 LD Oct. 30 - Jan. 5 NHATS target
6.41 LD today 2018 YM2 40 m  6.41 LD Dec. 28 - Jan. 3 Earth closest at 0108 UTC - DOU
7.8   LD Jan. 6* 2018 XO4 30 m  9.4 from 10.0 LD yesterday - Jan. 13 EPU +/- 17 mins.*, NHATS target
* EPU = Earth passage uncertainty

This report was generated at 1940 UTC with follow-up in today's DOU MPEC for passing 2018 YM2, departed objects 2018 YK2 and 2018 YA1, and distant 68216 2001 CV26.

Earth passage I D ~Size Distance today  Inside ten LD Notes
7.3   LD Jan. 9* 2013 YM2 19 m  11.0 from 11.8 LD Jan. 2 - 16 EPU +/- 3.75 days*, NHATS target

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 (2007) but is not currently coming so close. Object temporal distances are derived 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 31 December '18

The MPC's NEO Confirmation Page has 24 listings

When last checked at 2358 UTC today, the Minor Planet Center's Near Earth Object discovery Confirmation Page (NEOCP) had 24 objects listed. Of these, nineteen 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 31 December '18

Minor Planet Electronic Circulars

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

<< DOU on 31 Dec. '18 >>  MPEC 2018-Y101 - "13:05 UT" - Daily Orbit Update

MPEC 2018-Y100 - "04:16 UT" - 2011 PF2

MPEC 2018-Y99 - "00:57 UT" - 2018 PL28

MPEC 2018-Y98 - "00:34 UT" - 2008 SN1

Observers  on 31 December '18

Nineteen observers appear in today's MPECs.

CodeObserver / observatory
L2729PREMOTE Obs., 1 in MPEC 2018-Y101 -- 3200
160Castelmartini Obs. in Italy, 7 in MPEC 2018-Y101 -- 2018 WR1, 345722, 325395, 217807, 18109, 136793, 3200
807|Robert Holmes in Illinois via Cerro Tololo Inter-American Obs. (CTIO) in Chile, 3 in MPEC 2018-Y101 -- 2018 YE2, 2018 YA, 2018 XV5
K83Forti Obs., 3 in MPEC 2018-Y101 -- 2003 NW1, 18736, 2061
I89'Steven M. Tilley in Louisiana via iTelescope Obs. Nerpio in Spain, 1 in MPEC 2018-Y101 -- 2018 XR
Q62`Steven M. Tilley in Louisiana via iTelescope Obs. Siding Spring in New South Wales, 1 in MPEC 2018-Y101 -- 2013 LH16
950.EURONEAR via La Palma in the Canary Islands, 1 in MPEC 2018-Y101 -- 25143
C94MASTER-II Tunka in Russia, 1 in MPEC 2018-Y101 -- 90403
A06Mataro Obs. in Spain, 8 in MPEC 2018-Y101 -- 2004 XP14, 86324, 68216, 523595, 418849, 345722, 1627, 1620
474Mt. John Obs. in New Zealand, 1 in MPEC 2018-Y101 -- 2018 YM2
G96Mt. Lemmon Survey in Arizona, 1 in MPEC 2018-Y99 -- 2018 PL28
Z80Northolt Branch Obs. in England, 1 in MPEC 2018-Y101 -- 2018 YK2
F51Pan-STARRS 1 (PS1) in Hawaii, 3 in MPECs 2018-Y98, 2018-Y99 & 2018-Y100 -- 2018 PL28, 2011 PF2, 2008 SN1
619Sabadell Obs. in Spain, 2 in MPEC 2018-Y101 -- 2007 YQ56, 2004 XP14
233San Vito Obs. in Italy, 2 in MPEC 2018-Y101 -- 418849, 1943
C95SATINO-1 in France, 1 in MPEC 2018-Y101 -- 3288
691Spacewatch 0.9m telescope in Arizona, 8 in MPEC 2018-Y101 -- 2018 XU2, 2018 XN, 2018 XD5, 2018 XB4, 2018 WR1, 2018 UZ, 2018 RR7, 1998 YF10
291Spacewatch 1.8m telescope in Arizona, 8 in MPEC 2018-Y101 -- 2018 YZ1, 2018 YJ, 2018 YA1, 2018 XK5, 2018 XG5, 2018 VK10, 2018 UY, 2017 QP17
T12UH/Tholen NEO Follow-Up 2.24m Telescope in Hawaii, 1 in MPEC 2018-Y101 -- 2018 UD1
For a list of all participating observatories that have Web addresses, see A/CC's Observatory Links page.

Impact Risk Monitoring  on 31 December '18

Summary Risk Table for Risk Assessments Updated Today   (last checks: NEODyS at 2358 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 Sentry1705R E M O V E DJPL: Risk listing removed at 1527 UTC today
2018 XG5JPL Sentry17052083-208324.3696e-07-4.16-4.170JPL: Computed at 07:27 today Pacific time based on 37 observations spanning 17.789 days (2018-Dec-13.39431 to 2018-Dec-31.18359). Diameter approximately 0.300 km. from weighted mean H=20.27.
2018 XB4JPL Sentry17052052-2118546.78801917e-05-3.95-4.250JPL: Computed at 07:38 today Pacific time based on 36 observations spanning 17.801 days (2018-Dec-13.34358 to 2018-Dec-31.14473). Diameter approximately 0.055 km. from weighted mean H=23.96.
2016 AZ193JPL Sentry17052019-21144982.1976626e-06-6.30-7.220JPL: Computed at 14:28 April 6th of 2017 Pacific time based on 9 observations spanning .15930 days (2016-Jan-03.25638 to 2016-Jan-03.41568). Diameter approximately 0.016 km. from weighted mean H=26.62.

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 31 December '18

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

1940Generated Traffic Report
1705Noted that JPL Sentry has updated its 2016 AZ193 risk assessment - see above
Noted that JPL Sentry has updated its 2018 XB4 risk assessment - see above
Noted that JPL Sentry has updated its 2018 XG5 risk assessment - see above
Noted that JPL Sentry has removed 2018 YZ1 as an impact risk - see above
Grabbed MPEC 2018-Y101 - Daily Orbit Update - see above
0515Grabbed MPEC 2018-Y98 - 2008 SN1 - see above
Grabbed MPEC 2018-Y99 - 2018 PL28 - see above
Grabbed MPEC 2018-Y100 - 2011 PF2 - see above