Contents  on 18 December '17

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 18 December '17

Ten objects reported inside ten LD

There are ten small Solar-System bodies known to be inside ten lunar distances (LD) of Earth today. Nearest is 2017 XY61, inbound from 5.04 to 2.80 LD, while 2017 XW61 comes its closest to our planet this time around, reaching 3.11 LD at 0432 UTC.

Earth passage I D ~Size Distance today  Inside ten LD Notes
2.51 LD tomorrow 2017 XY61 19 m  2.80 from 5.04 LD Dec. 16 - 22
3.11 LD today 2017 XW61 27 m  3.11 LD Dec. 14 - 21 Earth closest at 0432 UTC
3.35 LD Dec. 14 2006 XY 54 m  5.05 to 5.90 LD Dec. 5 - 23 NHATS target
3.83 LD yesterday 2017 VT14 80 m  4.40 to 5.90 LD Dec. 13 - 21 radar target, comet nucleus?
4.51 LD Dec. 15 2017 XY2 13 m  6.73 to 8.18 LD Dec. 10 - 20 NHATS target, risk
5.16 LD today 2017 XW60 8 m  5.16 LD Dec. 13 - 22 Earth closest at 0010 UTC
6.14 LD Dec. 15 2017 XK1 31 m  9.57 to 11.82 LD Dec. 12 - 18 exits ten LD
7.61 LD Dec. 24 2017 WZ14 31 m  9.97 from 10.72 LD today - Dec. 30 radar/NHATS target, enters ten LD
7.94 LD yesterday 2017 XT60 11 m  7.94 to 8.12 LD Dec. 14 - 21
8.15 LD today 2017 XX61 16 m  8.15 LD Dec. 16 - 20 Earth closest at 1449 UTC
Approaching (sorted by 10-LD bubble entry date)
3.7   LD Feb. 24* 2017 DR109 10 m  151.8 from 154.9 LD Feb. 18 - March 1 EPU +/- 30 mins.*, NHATS target
3.8   LD March 7* 2017 VR12 265 m  110.0 from 111.8 LD Feb. 28 - March 13 EPU +/- 15 mins.*, radar/NHATS target
* EPU = Earth passage uncertainty

This report was generated at 1941 UTC with first follow-up in today's DOU MPEC for departed 2017 XZ61 along with astrometry from earlier this month for departed 2017 VC.



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. 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 18 December '17

The MPC's NEO Confirmation Page has 29 listings

When last checked at 2358 UTC today, the Minor Planet Center's Near Earth Object discovery Confirmation Page (NEOCP) had 29 objects listed. Of these, six were "one nighters." So far The Tracking News has counted a total of 30 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 18 December '17

Minor Planet Electronic Circulars

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


MPEC 2017-Y29 - "14:11 UT" - 2016 GZ215


MPEC 2017-Y28 - "14:09 UT" - 2015 YA10


<< DOU on 18 Dec. '17 >>  MPEC 2017-Y27 - "13:05 UT" - Daily Orbit Update

Observers  on 18 December '17

Twelve observers appear in today's MPECs.

CodeObserver / observatory
H21Astronomical Research Obs. Westfield in Illinois, 22 in MPEC 2017-Y27 -- 2017 XT2, 2017 WV13, 2017 WS1, 2017 WF13, 2017 VX14, 2017 VW13, 2017 VN15, 2017 VM2, 2017 VC, 2017 UF43, 2017 UD45, 2017 UA45, 2017 TR3, 2017 SS19, 2017 SP19, 2017 SO17, 2017 RK1, 2017 OR18, 2017 NL6, 2008 WQ63, 354101, 8567
T08ATLAS Mauna Loa in Hawaii, 6 in MPEC 2017-Y27 -- 2017 UE45, 505667, 504928, 294739, 285567, 16834
807|Robert Holmes in Illinois via Cerro Tololo Inter-American Obs. (CTIO) in Chile, 8 in MPEC 2017-Y27 -- 2017 XK60, 2017 XE2, 2017 WU13, 2017 WL1, 2017 VK1, 2017 OP19, 2017 OD1, 2015 OH
J04ESA Optical Ground Station (ESA OGS) in the Canary Islands, 4 in MPECs 2017-Y27, 2017-Y28 & 2017-Y29 -- 2017 WT1, 2017 VW13, 2016 GZ215, 2015 YA10
006Fabra Obs. in Spain, 4 in MPEC 2017-Y27 -- 163696, 140158, 3200, 1980
P93JAXA Space Tracking & Communications Center (JAXA STCC) in Japan, 2 in MPEC 2017-Y27 -- 1999 AF4, 3200
W08Jimginny Obs., 1 in MPEC 2017-Y27 -- 3200
J43Oukaimeden Obs. in Morocco, 1 in MPEC 2017-Y27 -- 8567
H23Pear Tree Obs. in Florida, 1 in MPEC 2017-Y27 -- 495858
204Schiaparelli Obs. in Italy, 2 in MPEC 2017-Y27 -- 2009 WZ7, 3200
K14Sencelles Obs. in Spain, 1 in MPEC 2017-Y27 -- 3122
587Sormano Obs. in Italy, 1 in MPEC 2017-Y27 -- 2017 XZ61
For a list of all participating observatories that have Web addresses, see A/CC's Observatory Links page.

Impact Risk Monitoring  on 18 December '17

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 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 NASA/JPL Sentry and NEODyS CLOMON2 risk pages.
0000NNN000

Object

Risk
Monitor
When
Noted
UTC
0000T0000
Year
Range

VI
#
000NN00
Prob
Cum
T0000
PS
Cum
T0000
PS
Max

T
S


Notes for Today's Latest Risk Assessments
2017 VW13JPL Sentry17552097-209722.6762e-06-3.71-3.760JPL: Computed at 09:51 today Pacific time based on 191 observations spanning 34.413 days (2017-Nov-13.64011 to 2017-Dec-18.05333). Diameter approximately 0.250 km. from weighted mean H=20.63.
2017 UA45JPL Sentry18362099-211251.98453e-06-6.62-6.730JPL: Computed at 10:06 today Pacific time based on 39 observations spanning 44.580 days (2017-Oct-27.47452 to 2017-Dec-11.054117). Diameter approximately 0.022 km. from weighted mean H=25.95.

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 18 December '17

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

1941Generated Traffic Report
1836Noted that JPL Sentry has updated its 2017 UA45 risk assessment - see above
1755Noted that JPL Sentry has updated its 2017 VW13 risk assessment - see above
1608Grabbed MPEC 2017-Y27 - Daily Orbit Update - see above
Grabbed MPEC 2017-Y28 - 2015 YA10 - see above
Grabbed MPEC 2017-Y29 - 2016 GZ215 - see above