Contents  on 27 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 27 April '18

One object reported inside ten LD

Today one asteroid is reported inside ten lunar distances (LD) of Earth. Risk-listed intruder 2018 HW1 moves away from us, from 5.50 to 6.56 LD.

Neighborhood Traffic
Earth passage I D ~Size Distance today  Inside ten LD Notes
0.89 LD April 21 2018 HW1 22 m  5.50 to 6.56 LD April 12 - May 1 intruder, NHATS target, risk - DOU

This report was generated at 1750 UTC with first follow-up for outbound risk-listed intruder 2018 HW1 in today's DOU MPEC, along with continuing follow-up for three objects on approach: 2018 EJ4, 388945 2008 TZ3, and 1999 FN19.

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  24.9 from 27.2 LD May 4 - 11 EPU +/- 14.00 hours*
9.65 LD May 7 1999 FN19 112 m  15.50 from 16.50 LD May 5 - 9 radar/NHATS target - DOU
6.48 LD May 9 388945 2008 TZ3 282 m  24.33 from 26.35 LD May 5 - 13 DOU
9.50 LD May 29 68347 2001 KB67 371 m  103.32 from 99.70 LD May 28 - 30 radar target
5.56 LD June 10 2018 EJ4 186 m  58.52 from 59.76 LD June 4 - 16 radar/NHATS target - DOU
8.96 LD June 11 2015 DP155 162 m  40.41 from 41.13 LD June 6 - 15 NHATS target
* EPU = Earth passage uncertainty

<< Reading:  Bad Astronomy (Phil Plait) shows some spectacular amateur-assembled animations compiled from Rosetta mission images of 67P/Churyumov-Gerasimenko that display an alien landscape amidst a storm of ice and dust particles (and background stars, which are clarified in this version). A recent science preprint discusses how this comet may have gotten its bi-lobed shape. Switching topics, Bad Astronomy also has a recent post about Main Belt asteroid 216 Kleopatra -- its shape, its two moons, its local gravity environment, and its status as "the second largest metal asteroid in the solar system." (The largest is 16 Psyche, which is scheduled to be studied during 2026-27 by NASA's Psyche mission.)

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 27 April '18

The MPC's NEO Confirmation Page has 17 listings

When last checked at 2358 UTC today, the Minor Planet Center's Near Earth Object discovery Confirmation Page (NEOCP) had seventeen objects listed. Of these, seven were "one nighters."

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 27 April '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.

MPEC 2018-H97 - "17:31 UT" - 2015 KE172

<< DOU on 27 Apr. '18 >>  MPEC 2018-H96 - "12:04 UT" - Daily Orbit Update

MPEC 2018-H95 - "04:06 UT" - 2017 SO2

MPEC 2018-H94 - "03:33 UT" - 2015 VD66

Observers  on 27 April '18

Sixteen observers appear in today's MPECs.

CodeObserver / observatory
T05ATLAS Haleakala in Hawaii, 4 in MPEC 2018-H96 -- 85628, 337084, 138847, 1627
T08ATLAS Mauna Loa in Hawaii, 1 in MPEC 2018-H96 -- 152931
703Catalina Sky Survey (CSS) in Arizona, 14 in MPEC 2018-H96 -- 2018 HH2, 2018 DB2, 2017 WH14, 1999 FN19, 85953, 68950, 474574, 37655, 374851, 36284, 164201, 15745, 8037, 3122
807|Robert Holmes in Illinois via Cerro Tololo Inter-American Obs. (CTIO) in Chile, 10 in MPECs 2018-H94, 2018-H95 & 2018-H96 -- 2018 HW1, 2018 HC, 2018 GR5, 2018 FX1, 2018 FW2, 2018 FL4, 2018 CC14, 2017 XG2, 2017 SO2, 2015 VD66
K83Forti Obs., 7 in MPEC 2018-H96 -- 2018 FQ5, 2003 FS2, 85628, 388945, 25916, 136839, 1627
H15ISON New Mexico Obs. in New Mexico, 1 in MPEC 2018-H96 -- 242643
K22Les Barres Obs. in France, 1 in MPEC 2018-H96 -- 1627
568@Jean-Marc Petit on Mauna Kea in Hawaii, 1 in MPEC 2018-H97 -- 2015 KE172
G96Mt. Lemmon Survey (MLS) in Arizona, 6 in MPEC 2018-H96 -- 2015 TX143, 513550, 434051, 285339, 164201, 1866
I41Palomar Transient Factory (PTF) in southern California, 3 in MPEC 2018-H96 -- 2014 JC31, 37655, 1866
Y00SONEAR in Brazil, 5 in MPEC 2018-H96 -- 2018 HW1, 2018 DX3, 450648, 242643, 194126
691Spacewatch 0.9m telescope in Arizona, 1 in MPEC 2018-H96 -- 2013 JY35
291Spacewatch 1.8m telescope in Arizona, 1 in MPEC 2018-H96 -- 2018 EJ4
I52Steward Obs. Mt. Lemmon Station in Arizona, 10 in MPEC 2018-H96 -- 2018 HV1, 2018 HR1, 2018 HQ1, 2018 HB1, 2018 GW4, 2018 GL, 2018 GA5, 2018 GA4, 2018 EJ4, 2015 JP
T12UH/Tholen NEO Follow-Up 2.24m Telescope in Hawaii, 1 in MPEC 2018-H96 -- 2017 SO2
I15Wishing Star Obs. in Rhode Island, 3 in MPEC 2018-H96 -- 2017 VL15, 2016 JP, 285339
For a list of all participating observatories that have Web addresses, see A/CC's Observatory Links page.

Impact Risk Monitoring  on 27 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.





Notes for Today's Latest Risk Assessments
2018 HJ2NEODyS1520208511.6e-05-4.58-4.580NEODyS: "Based on 50 optical observations (of which 0 are rejected as outliers) from 2018-04-23.412 to 2018-04-26.412."
2018 HW1JPL Sentry15452116-211821.36295e-05-5.81-5.820JPL: Computed at 07:55 today Pacific time based on 45 observations spanning 3.8342 days (2018-Apr-23.20248 to 2018-Apr-27.03664). Diameter approximately 0.022 km. from weighted mean H=25.94.
2018 GR4NEODyS15202048-21161901.41e-04-5.02-5.240NEODyS: "Based on 57 optical observations (of which 1 are rejected as outliers) from 2018-04-12.318 to 2018-04-24.167."
2018 GE2NEODyS15202054-21172196.14e-05-5.47-6.10NEODyS: "Based on 100 optical observations (of which 4 are rejected as outliers) from 2018-04-10.411 to 2018-04-26.264."

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 27 April '18

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

1801Grabbed MPEC 2018-H97 - 2015 KE172 - see above
1750Generated Traffic Report
1545Noted that JPL Sentry has updated its 2018 HW1 risk assessment - see above
1520Noted that NEODyS has updated its 2018 GE2 risk assessment - see above
Noted that NEODyS has updated its 2018 GR4 risk assessment - see above
Noted that NEODyS has posted 2018 HJ2 as an impact risk - see above
Grabbed MPEC 2018-H96 - Daily Orbit Update - see above
0421Grabbed MPEC 2018-H95 - 2017 SO2 - see above
0337Grabbed MPEC 2018-H94 - 2015 VD66 - see above