Contents  on 21 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 21 December '17

Eight objects reported inside ten LD

Eight planetesimals are known to be traveling within ten lunar distances (LD) of our planet today. Nearest is 2017 YE, which moves in from 3.22 to 2.91 LD.

Earth passage I D ~Size Distance today  Inside ten LD Notes
2.51 LD Dec. 19 2017 XY61 19 m  5.57 to 8.46 LD Dec. 16 - 22
2.88 LD tomorrow 2017 YE 7 m  2.91 from 3.22 LD Dec. 13 - 31 NHATS target - DOU
3.11 LD Dec. 18 2017 XW61 27 m  8.02 to 10.49 LD Dec. 14 - 21 exits ten LD
3.35 LD Dec. 14 2006 XY 54 m  7.79 to 8.78 LD Dec. 5 - 23 NHATS target
3.83 LD Dec. 17 2017 VT14 80 m  9.93 to 12.11 LD Dec. 13 - 21 radar target, exits ten LD, comet nucleus?
5.16 LD Dec. 18 2017 XW60 9 m  7.83 to 9.40 LD Dec. 13 - 22
7.62 LD Dec. 24 2017 WZ14 33 m  8.24 from 8.72 LD Dec. 18 - 30 radar/NHATS target
7.93 LD Dec. 17 2017 XT60 11 m  9.31 to 10.23 LD Dec. 14 - 21 exits ten LD - DOU
Approaching (sorted by 10-LD bubble entry date)
3.7   LD Feb. 24* 2017 DR109 10 m  142.5 from 145.6 LD Feb. 18 - March 1 EPU +/- 30 mins.*, NHATS target
3.8   LD March 7* 2017 VR12 267 m  104.7 from 106.4 LD Feb. 28 - March 13 EPU +/- 9 mins.*, radar/NHATS target - DOU
* EPU = Earth passage uncertainty

This report was generated at 1922 UTC with first follow-up in today's DOU MPEC for inbound 2017 YE along with continuing follow-up for approaching 2017 VR12, outbound 2017 XT60, departed objects 2017 XZ61 and 2017 XS, and distant 208023 1999 AQ10, plus further observation from October of 2017 TY5 (6.85 days added to 4.10-day arc) and 2017 TH2.



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 come within ten LD since A/CC began these traffic reports (2007) but is not presently 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 21 December '17

The MPC's NEO Confirmation Page has 51 listings

When last checked at 2358 UTC today, the Minor Planet Center's Near Earth Object discovery Confirmation Page (NEOCP) had 51 objects listed. Of these, eighteen were "one nighters." So far The Tracking News has counted a total of 54 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 '17

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 21 Dec. '17 >>  MPEC 2017-Y50 - "13:05 UT" - Daily Orbit Update


MPEC 2017-Y49 - "12:50 UT" - 2008 OP8


MPEC 2017-Y48 - "00:16 UT" - 2017 YH


MPEC 2017-Y47 - "00:05 UT" - 2017 XL62

Observers  on 21 December '17

Seventeen observers appear in today's MPECs.

CodeObserver / observatory
H21Astronomical Research Obs. Westfield in Illinois, 13 in MPEC 2017-Y50 -- 2017 XS60, 2017 VU14, 2017 VA13, 2017 UP51, 2017 UO6, 2017 UC43, 2017 UA8, 2017 TY5, 2017 TH2, 2017 ST11, 475967, 154988, 7977
T08ATLAS Mauna Loa in Hawaii, 1 in MPEC 2017-Y48 -- 2017 YH
703Catalina Sky Survey (CSS) in Arizona, 27 in MPEC 2017-Y50 -- 2017 WX12, 2017 VR12, 2014 VU1, 2013 US3, 507366, 482796, 475967, 439908, 417201, 36284, 337228, 302311, 281365, 237805, 208023, 177651, 177255, 17511, 163696, 152931, 137924, 137078, 137062, 111253, 10165, 6053, 1864
807|Robert Holmes in Illinois via Cerro Tololo Inter-American Obs. in Chile, 1 in MPEC 2017-Y47 -- 2017 XL62
J04ESA Optical Ground Station in the Canary Islands, 1 in MPEC 2017-Y48 -- 2017 YH
J14La Corte Obs. in the Canary Islands, 1 in MPEC 2017-Y50 -- 3200
B67Mirasteilas Obs. in Switzerland, 2 in MPEC 2017-Y50 -- 2017 XL2, 2014 YC15
G96Mt. Lemmon Survey (MLS) in Arizona, 48 in MPECs 2017-Y47, 2017-Y49 & 2017-Y50 -- 2017 XQ60, 2017 XL62, 2017 XG1, 2017 XB62, 2017 XB1, 2017 WK14, 2017 UR7, 2017 OH68, 2017 OD1, 2017 OA, 2015 YG, 2015 XK1, 2015 TM237, 2015 OH, 2013 YY13, 2009 WZ7, 2008 OP8, 2007 XP3, 2004 VC17, 90075, 87024, 86819, 68548, 506437, 483560, 474223, 35432, 333888, 326777, 253841, 242211, 23714, 190166, 189700, 162998, 162472, 162004, 153311, 137799, 137126, 136793, 12923, 112221, 9856, 8201, 7336, 5587, 5189
D29Purple Mtn. Obs. Xuyi Station in China, 1 in MPEC 2017-Y50 -- 420302
G40!M. Kumrucu-Lohmiller in Massachusetts via Slooh.com Canary Islands Obs. in the Canary Islands, 1 in MPEC 2017-Y50 -- 302311
W881Tony Evans in Portugal via Slooh.com Chile Obs. in Chile, 1 in MPEC 2017-Y50 -- 2017 XS
691Spacewatch 0.9m telescope in Arizona, 14 in MPECs 2017-Y47 & 2017-Y50 -- 2017 XP61, 2017 XL62, 2017 XL60, 2017 XB62, 2017 XB1, 2017 WW12, 2017 WG2, 2017 SS19, 2017 RH15, 2017 OP19, 2017 NU6, 2012 PN28, 2003 YX1, 333888
291Spacewatch 1.8m telescope in Arizona, 6 in MPECs 2017-Y47 & 2017-Y50 -- 2017 XL62, 2017 XF2, 2017 WK14, 2017 VX13, 2017 MB1, 2016 YW7
I52Steward Obs. Mt. Lemmon Station in Arizona, 12 in MPECs 2017-Y47 & 2017-Y50 -- 2017 YE, 2017 YD, 2017 XZ61, 2017 XR2, 2017 XL62, 2017 XL2, 2017 XK61, 2017 XF62, 2017 XF2, 2017 XE62, 2017 XD62, 2017 WV13
926Tenagra II Obs. in Arizona, 6 in MPECs 2017-Y48 & 2017-Y50 -- 2017 YH, 2017 XX2, 2017 XV60, 2017 XV2, 2017 XT60, 2017 XQ60
T12UH/Tholen NEO Follow-Up 2.24m Telescope in Hawaii, 1 in MPEC 2017-Y50 -- 2015 YC18
C51WISE in Earth polar orbit, 4 in MPEC 2017-Y50 -- 2017 UR7, 496861, 17182, 16834
For a list of all participating observatories that have Web addresses, see A/CC's Observatory Links page.

Impact Risk Monitoring  on 21 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 XS2NEODyS17032099-2116151.79e-04-4.75-4.790NEODyS: "Based on 21 optical observations (of which 1 are rejected as outliers) from 2017-12-11.360 to 2017-12-20.351."
2017 XO2NEODyS17032028-2096224.5e-06-3.97-3.990NEODyS: "Based on 28 optical observations (of which 1 are rejected as outliers) from 2017-12-10.337 to 2017-12-20.299."
2017 VW13NEODyS1703209724.27e-08-5.50-5.510NEODyS: "Based on 190 optical observations (of which 6 are rejected as outliers) from 2017-11-13.641 to 2017-12-19.077."
2014 JT79JPL Sentry19042018-211611341.8746316e-06-6.25-7.510JPL: Computed at 19:19 April 6th Pacific time based on 11 observations spanning 2.8075 days (2014-May-02.40649 to 2014-May-05.21401). Diameter approximately 0.013 km. from weighted mean H=27.12.
2010 GZ60JPL Sentry19042018-21164785.4117641e-06-0.83-1.750JPL: Computed at 13:26 April 18th Pacific time based on 14 observations spanning 1.2571 days (2010-Apr-05.71913 to 2010-Apr-06.97621). Diameter approximately 2.000 km. from weighted mean H=16.14.

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 21 December '17

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

1922Generated Traffic Report
1904Noted that JPL Sentry has updated its 2010 GZ60 risk assessment - see above
Noted that JPL Sentry has updated its 2014 JT79 risk assessment - see above
1703Noted that NEODyS has updated its 2017 VW13 risk assessment - see above
Noted that NEODyS has updated its 2017 XO2 risk assessment - see above
Noted that NEODyS has updated its 2017 XS2 risk assessment - see above
Grabbed MPEC 2017-Y49 - 2008 OP8 - see above
Grabbed MPEC 2017-Y50 - Daily Orbit Update - see above
0018Grabbed MPEC 2017-Y47 - 2017 XL62 - see above
Grabbed MPEC 2017-Y48 - 2017 YH - see above