Contents  on 20 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 20 December '17

Ten objects reported inside ten LD

Ten transient natural objects are reported inside ten lunar distances (LD) of Earth today. 2017 XY61 is the nearest, but headed away from 3.12 to 5.57 LD, while 2017 YE moves in from 3.80 to 3.22 LD.

Earth passage I D ~Size Distance today  Inside ten LD Notes
2.51 LD yesterday 2017 XY61 19 m  3.12 to 5.57 LD Dec. 16 - 22 DOU
2.88 LD Dec. 22 2017 YE 7 m  3.22 from 3.80 LD Dec. 13 - 31 NHATS target
3.11 LD Dec. 18 2017 XW61 27 m  5.69 to 8.02 LD Dec. 14 - 21
3.35 LD Dec. 14 2006 XY 54 m  6.83 to 7.79 LD Dec. 5 - 23 NHATS target
3.83 LD Dec. 17 2017 VT14 80 m  7.83 to 9.93 LD Dec. 13 - 21 radar target, comet nucleus?
4.51 LD Dec. 15 2017 XY2 13 m  9.75 to 11.40 LD Dec. 10 - 20 NHATS target, exits ten LD, risk
5.16 LD Dec. 18 2017 XW60 9 m  6.48 to 7.83 LD Dec. 13 - 22 DOU
7.62 LD Dec. 24 2017 WZ14 33 m  8.72 from 9.30 LD Dec. 18 - 30 radar/NHATS target - DOU
7.93 LD Dec. 17 2017 XT60 12 m  8.59 to 9.31 LD Dec. 14 - 21 DOU
8.15 LD Dec. 18 2017 XX61 16 m  9.48 to 11.66 LD Dec. 16 - 20 exits ten LD
Approaching (sorted by 10-LD bubble entry date)
3.7   LD Feb. 24* 2017 DR109 10 m  145.6 from 148.7 LD Feb. 18 - March 1 EPU +/- 30 mins.*, NHATS target
3.8   LD March 7* 2017 VR12 265 m  106.4 from 108.2 LD Feb. 28 - March 13 EPU +/- 15 mins.*, radar/NHATS target
* EPU = Earth passage uncertainty

This report was generated at 1846 UTC with first follow-up in today's DOU MPEC for outbound objects 2017 XY61 and 2017 XT60, and from observation in mid-October, 2017 TH2 (5.31 days added to its 1.76-day discovery arc), along with continuing follow-up for inbound 2017 WZ14 and departed 2017 WJ16 (observing arc more than doubled, from 12.18 to 25.15 days).



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 20 December '17

The MPC's NEO Confirmation Page has 47 listings

When last checked at 2359 UTC today, the Minor Planet Center's Near Earth Object discovery Confirmation Page (NEOCP) had 47 objects listed. Of these, 24 were "one nighters." So far The Tracking News has counted a total of 48 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 20 December '17

Minor Planet Electronic Circulars

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


<< DOU on 20 Dec. '17 >>  MPEC 2017-Y46 - "13:04 UT" - Daily Orbit Update

Observers  on 20 December '17

Seventeen observers appear in today's MPEC.

CodeObserver / observatory
H21Astronomical Research Obs. Westfield in Illinois, 22 in MPEC 2017-Y46 -- 2017 XM2, 2017 WY, 2017 WL2, 2017 WL14, 2017 WF2, 2017 WE13, 2017 VX14, 2017 VU, 2017 VM2, 2017 VL15, 2017 UG8, 2017 TH2, 2017 SM16, 2017 RK1, 2017 NL6, 2017 LU, 2017 CW1, 2015 RL82, 2015 EZ, 2014 WO7, 2011 CX7, 88188
A77Chante-Perdrix Obs. in France, 1 in MPEC 2017-Y46 -- 3200
822Cordoba Obs. in Argentina, 2 in MPEC 2017-Y46 -- 53110, 385580
J27El Guijo Obs. in Spain, 4 in MPEC 2017-Y46 -- 504887, 189173, 17511, 163696
134Groszschwabhausen Obs. in Germany, 1 in MPEC 2017-Y46 -- 190208
H15ISON New Mexico Obs. in New Mexico, 2 in MPEC 2017-Y46 -- 2017 NL6, 138205
130Lumezzane Obs. in Italy, 11 in MPEC 2017-Y46 -- 2017 XL2, 2017 VW13, 2017 NL6, 2014 VU1, 1997 GC32, 506859, 504887, 497096, 349928, 189173, 16657
G96Mt. Lemmon Survey (MLS) in Arizona, 8 in MPEC 2017-Y46 -- 2017 XJ61, 2017 NL6, 2001 VC2, 370061, 322763, 141765, 101873, 9950
557Ondrejov Obs. in the Czech Republic, 1 in MPEC 2017-Y46 -- 17511
691Spacewatch 0.9m telescope in Arizona, 25 in MPEC 2017-Y46 -- 2017 XR61, 2017 XP61, 2017 XG2, 2017 XB62, 2017 XB1, 2017 WX13, 2017 WU13, 2017 WL13, 2017 WK14, 2017 WG2, 2017 UZ4, 2017 UF52, 2017 UE45, 2017 SS19, 2017 RH15, 2017 QL33, 2017 OP19, 2014 WG365, 2014 KT76, 2012 PN28, 2009 WZ7, 2004 BB, 2003 YX1, 210012, 1916
291Spacewatch 1.8m telescope in Arizona, 18 in MPEC 2017-Y46 -- 2017 XS2, 2017 XO2, 2017 WZ, 2017 WY14, 2017 WV13, 2017 WN16, 2017 WJ16, 2017 WC29, 2017 SL14, 2017 RR15, 2017 RL, 2015 MN116, 2014 YD42, 2010 SA17, 2008 EE5, 2007 WB, 2005 SQ, 1998 QP
V78Spirit Marsh Obs. in Minnesota, 1 in MPEC 2017-Y46 -- 3200
I52Steward Obs. Mt. Lemmon Station in Arizona, 24 in MPEC 2017-Y46 -- 2017 XX2, 2017 XV2, 2017 XU2, 2017 XT60, 2017 XS61, 2017 XR61, 2017 XR60, 2017 XQ61, 2017 XP61, 2017 XP60, 2017 XO60, 2017 XN61, 2017 XL61, 2017 XJ1, 2017 XG2, 2017 XC, 2017 WZ14, 2017 WK28, 2017 WK14, 2017 WE16, 2017 WE13, 2017 WD15, 2017 SO16, 2014 YD42
926Tenagra II Obs. in Arizona, 6 in MPEC 2017-Y46 -- 2017 XY61, 2017 XW60, 2017 XU2, 2017 XT60, 2017 XQ60, 2017 XP60
T12UH/Tholen NEO Follow-Up 2.24m Telescope in Hawaii, 1 in MPEC 2017-Y46 -- 2015 WM16
Z92West Park Obs. in England, 1 in MPEC 2017-Y46 -- 3200
C51WISE in Earth polar orbit, 8 in MPEC 2017-Y46 -- 2017 UR7, 2015 YE18, 1997 GC32, 496861, 307493, 294739, 185853, 16834
For a list of all participating observatories that have Web addresses, see A/CC's Observatory Links page.

Impact Risk Monitoring  on 20 December '17

Summary Risk Table for Risk Assessments Updated Today   (last checks: NEODyS 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 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 XS2JPL Sentry17112104-211689.01057031e-05-5.05-5.090JPL: Computed at 08:46 today Pacific time based on 21 observations spanning 8.9905 days (2017-Dec-11.35957 to 2017-Dec-20.35006). Diameter approximately 0.020 km. from weighted mean H=26.18.
NEODyS16072104-2116151.77e-04-4.76-4.840NEODyS: "Based on 19 optical observations (of which 1 are rejected as outliers) from 2017-12-11.360 to 2017-12-19.380."
2017 XO2JPL Sentry16342035-2111801.72504194e-05-3.47-3.750JPL: Computed at 08:15 today Pacific time based on 28 observations spanning 9.9623 days (2017-Dec-10.33601 to 2017-Dec-20.29832). Diameter approximately 0.110 km. from weighted mean H=22.45.
NEODyS16072028-2111233.64e-06-4.07-4.090NEODyS: "Based on 25 optical observations (of which 1 are rejected as outliers) from 2017-12-10.337 to 2017-12-18.899."
2017 VW13JPL Sentry16072097-209722.572e-06-3.72-3.770JPL: Computed at 07:52 today Pacific time based on 196 observations spanning 35.436 days (2017-Nov-13.64011 to 2017-Dec-19.076247). Diameter approximately 0.250 km. from weighted mean H=20.63.
NEODyS1607209725.95e-08-5.36-5.380NEODyS: "Based on 188 optical observations (of which 6 are rejected as outliers) from 2017-11-13.641 to 2017-12-19.077."
2017 UA45NEODyS16072099-211745.63e-07-7.16-7.630NEODyS: "Based on 40 optical observations (of which 7 are rejected as outliers) from 2017-10-27.475 to 2017-12-11.055."
2016 QJ44JPL Sentry2324R E M O V E DJPL: Risk listing removed at 1500 UTC Sept. 3rd

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 20 December '17

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

2324Noted that JPL Sentry has removed 2016 QJ44 as an impact risk - see above
1846Generated Traffic Report
1711Noted that JPL Sentry has updated its 2017 XS2 risk assessment - see above
1634Noted that JPL Sentry has updated its 2017 XO2 risk assessment - see above
1607Noted that NEODyS has updated its 2017 UA45 risk assessment - see above
Noted that JPL Sentry has updated its 2017 VW13 risk assessment - see above
Noted 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-Y46 - Daily Orbit Update - see above