Contents  on 25 April '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 25 April '18

Four objects reported inside ten LD

There are four asteroidal objects know to be inside ten lunar distances (LD) of Earth today. Nearest is newly announced risk-listed intruder 2018 HW1, which is outbound from 3.41 to 4.45 LD after passing Earth at 0.89 LD (and the Moon at 1.75 LD) on April 21st. The other three all leave our ten-LD traffic reporting "bubble."

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
0.40 LD April 22 2018 HV 6 m  8.19 to 11.76 LD April 19 - 25 intruder, exits ten LD
0.89 LD April 21 2018 HW1 22 m  3.41 to 4.45 LD April 12 - May 1 intruder, risk - MPEC, DOU
7.09 LD April 21 2018 HT 14 m  9.51 to 10.71 LD April 17 - 25 exits ten LD
9.49 LD April 23 2018 HY1 29 m  9.73 to 10.26 LD April 21 - 25 exits ten LD - MPEC, DOU

This report was generated at 1720 UTC with three discoveries announced late yesterday: outbound objects 2018 HY1 (MPEC) and risk-listed intruder 2018 HW1 (MPEC), and departed 2018 HX1 (MPEC), which flew by us at 2.69 LD on April 22nd. Today's DOU MPEC has additional observation of all three of those plus follow-up for approaching 388945 2008 TZ3 and departed objects 2018 HL1 and 2018 HU.

Approaching Traffic - sorted by 10-LD bubble entry date
Earth passage I D ~Size Distance today  Inside ten LD Notes
6.2   LD May 8* 2016 JQ5 8 m  29.6 from 32.0 LD May 4 - 11 EPU +/- 14.00 hours*
9.65 LD May 7 1999 FN19 112 m  17.53 from 18.57 LD May 5 - 9 radar/NHATS target
6.48 LD May 9 388945 2008 TZ3 282 m  28.40 from 30.45 LD May 5 - 13 DOU
9.50 LD May 29 68347 2001 KB67 371 m  106.98 from 110.69 LD May 28 - 30 radar target
5.6   LD June 10* 2018 EJ4 186 m  61.0 from 62.2 LD June 4 - 16 EPU +/- 5 mins.*, radar/NHATS target
8.96 LD June 11 2015 DP155 162 m  41.85 from 42.55 LD June 6 - 15 NHATS target
* EPU = Earth passage uncertainty



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 25 April '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, four 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 25 April '18

Minor Planet Electronic Circulars

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


<< DOU on 25 Apr. '18 >>  MPEC 2018-H84 - "12:05 UT" - Daily Orbit Update


MPEC 2018-H83 - "02:45 UT" - 2001 SC170 = 2018 HP1

Id. F. Manca

Observers  on 25 April '18

A total of 21 observers appear in today's MPECs.

CodeObserver / observatory
T05ATLAS Haleakala in Hawaii, 9 in MPEC 2018-H84 -- 2017 WH14, 2013 US3, 85953, 37655, 285339, 152931, 137062, 11066, 1866
160Castelmartini Obs. in Italy, 15 in MPEC 2018-H84 -- 2018 HX1, 2018 FQ5, 85628, 498548, 475967, 388945, 36183, 25916, 212359, 194126, 184990, 15745, 115052, 7889, 6569
703Catalina Sky Survey (CSS) in Arizona, 18 in MPECs 2018-H83 & 2018-H84 -- 2018 GR2, 2018 FQ5, 2010 JG88, 2009 SK104, 2001 SC170, 85628, 66251, 65674, 53435, 388945, 36183, 337084, 194126, 186822, 154656, 138847, 112985, 1627
850Cordell-Lorenz Obs. in Tennessee, 1 in MPEC 2018-H84 -- 85953
595Farra d'Isonzo Obs. in Italy, 2 in MPEC 2018-H84 -- 2018 HY1, 2018 HL1
203GiaGa Obs. in Italy, 2 in MPEC 2018-H84 -- 2018 HX1, 2018 GY1
E94Gisborne Obs. in New Zealand, 1 in MPEC 2018-H84 -- 2018 HW1
G48Harlingten Research Obs. in New Mexico, 5 in MPEC 2018-H84 -- 2018 GY1, 2018 FQ5, 2018 DX3, 2009 SK104, 388945
Q62?B. Lutkenhoner in Germany via iTelescope Obs. Siding Spring in New South Wales, 1 in MPEC 2018-H84 -- 2018 HW1
Z43Landehen Obs., 2 in MPEC 2018-H84 -- 2018 BY2, 1627
K30Luscherz Obs. in Switzerland, 1 in MPEC 2018-H84 -- 164201
K38M57 Obs. in Italy, 1 in MPEC 2018-H84 -- 2018 HX1
G96Mt. Lemmon Survey (MLS) in Arizona, 9 in MPECs 2018-H83 & 2018-H84 -- 2018 HH, 2018 DB2, 2013 GZ7, 2012 HO1, 2005 JD46, 2001 SC170, 36183, 248926, 141053
I41Palomar Transient Factory (PTF) in southern California, 3 in MPEC 2018-H84 -- 2018 GL, 508767, 212359
H45Petit Jean Mtn. South Obs. (PJMSO) in Arkansas, 2 in MPEC 2018-H84 -- 2018 FQ5, 2016 JP
K81PMPHR Obs., 1 in MPEC 2018-H84 -- 138847
D29Purple Mtn. Obs. Xuyi Station in China, 1 in MPEC 2018-H83 -- 2001 SC170
691Spacewatch 0.9m telescope in Arizona, 1 in MPEC 2018-H84 -- 498548
291Spacewatch 1.8m telescope in Arizona, 1 in MPEC 2018-H84 -- 2016 HV3
I52Steward Obs. Mt. Lemmon Station in Arizona, 12 in MPEC 2018-H84 -- 2018 HU, 2018 HP, 2018 HL1, 2018 HA1, 2018 GZ3, 2018 GQ5, 2018 GO4, 2018 GL1, 2018 GL, 2018 GA5, 2018 GA4, 2017 YE5
L01Visnjan Obs., 2 in MPEC 2018-H84 -- 2018 HX1, 2018 HO1
For a list of all participating observatories that have Web addresses, see A/CC's Observatory Links page.

Impact Risk Monitoring  on 25 April '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 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
2018 HW1NEODyS21002106-211861.52e-06-6.79-6.81-NEODyS #2 for the day: "Based on 24 optical observations (of which 0 are rejected as outliers) from 2018-04-23.203 to 2018-04-24.788."
JPL Sentry15402116-211831.248894e-05-5.87-5.870JPL: Computed at 08:14 today Pacific time based on 24 observations spanning 1.5843 days (2018-Apr-23.20248 to 2018-Apr-24.78681). Diameter approximately 0.022 km. from weighted mean H=25.97.
2008 UY91JPL Sentry15402022-2116485.15995e-08-6.65-7.180JPL: Computed at 08:58 April 7th of 2017 Pacific time based on 11 observations spanning .11968 days (2008-Oct-28.2208 to 2008-Oct-28.34048). Diameter approximately 0.036 km. from weighted mean H=24.84.

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 25 April '18

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

2100Noted that NEODyS has updated its 2018 HW1 risk assessment - see above
1720Generated Traffic Report
1540Noted that JPL Sentry has updated its 2008 UY91 risk assessment - see above
Noted that JPL Sentry has updated its 2018 HW1 risk assessment - see above
Noted that NEODyS has posted 2018 HW1 as an impact risk - see above
Grabbed MPEC 2018-H84 - Daily Orbit Update - see above
0444Grabbed MPEC 2018-H83 - 2001 SC170 = 2018 HP1 - see above