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Dec 3, 2016

The NEO 2016 WJ1 Has Been Removed from the Sentry Risk Table--Neodys Risk Table List 3 Possible Impacts 2106-2115.

On December 2, 2016 at 21:33(UTC) NASA JPL removed the NEO 2016 WJ1 from the Sentry Risk Table. Whenever an object is posted to one the risk lists (especially if it has a Torino Scale 1 or greater) and it is observable, observers will take a particular interest in it. In the case of 2016 WJ1 many follow-up observations where made and  there was a search in archives for precovery observations. From  November 24, 2016  to December 2, 2016  through the work of many observers from around the world the number of optical observations went from 68  to 240 and  the data-arc span went from 5 days to  4899 days (13.41 yr). This allowed  for the calculation of orbital elements with lower uncertainty and NASA JPL rule out  potential impacts well into the future. Notice: Neodys risk table list 3 possible impacts 2106-2115.
Background
(as of 2016-12-03 ) 
  • Object: 2016 WJ1 
  • Approximate Diameter: 140 m - 310 m (459.318 feet to 1017.06 feet)(Absolute Magnitude: H= 21.382)
  • Orbit Type: Apollo [NEO]- Potentially Hazardous Asteroid
  • On the Sentry Risk Table: No Removed on 2016-12-02 21:33
  • On the NEODyS CLOMON2 risk page: yes
  • Torino Scale(NEODyS CLOMON2): 0
    • The likelihood of a collision is zero, or is so low as to be effectively zero. Also applies to small objects such as meteors and bodies that burn up in the atmosphere as well as infrequent meteorite falls that rarely cause damage."
  • First(Precovery) Observation was made: 2003 07 04.605261
  • First(Precovery) Observed By: Mauna Kea (MPC Code 568) The Precovery M.P.E.C.:MPEC 2016-X21 : 2016 WJ1
  • Discovery (First) observation was made: 2016 11 19.46522
  • Discovery (First )observed by: Mt. Lemmon Survey (MPC Code G96) The Discovery M.P.E.C.: MPEC 2016-W38 : 2016 WJ1
  • Last Observation(publish): 2016 12 02.87233
    (by Nonndorf, Austria. (MPC Code C47 )
  • Data-Arc Span(publish) : 4900 days (13.42 yr)
  • Number of Optical Observations(published): 257
  • Observatories Reporting (Published) Observations(MPC Code):
    • (151) Eschenberg Observatory, Winterthur Switzerland.  
    • (160) Castelmartini,Italy.
    • (203) GiaGa Observatory,Italy.
    • (246) Klet Observatory-KLENOT, Czech Republic.
    • (291) LPL/Spacewatch II,US/Arizona. 
    • (568) Mauna Kea,US/Hawaii.
    • (691) Steward Observatory, Kitt Peak-Spacewatch, US/Arizona.
    • (926) Tenagra II Observatory, Nogales,US/Arizona.  
    • (958) Observatoire de Dax, France.
    • (A17) Guidestar Observatory, Weinheim,Germany.
    • (A48) Povegliano Veronese,Italy.
    • (C47) Nonndorf, Austria.
    • (C77) Bernezzo Observatory, Italy.
    • (E10) Siding Spring-Faulkes Telescope South, Australia/NSW.
    • (F51) Pan-STARRS 1, Haleakala, US/Hawaii.
    • (G96) Mt. Lemmon Survey, US/Arizona.
    • (H06) iTelescope Observatory, Mayhill, US/New Mexico.  
    • (H21) Astronomical Research Observatory, Westfield, US/Illinois.
    • (H45) Arkansas Sky Obs., Petit Jean Mountain South, US/Arkansas.
    • (I52) Steward Observatory, Mt. Lemmon Station,US/Arizona.
    • (J04) ESA Optical Ground Station, Tenerife, Canary Islands (Spain).
    • (J69) North Observatory, Clanfield,UK.
    • (K38) M57 Observatory, Saltrio,Italy.
    • (K61) Rokycany Observatory,Czech Republic.
    • (K65) Cesena,Italy.
    • (K74) Muensterschwarzach Observatory, Schwarzach, Germany.
    • (K88) GINOP-KHK, Piszkesteto, Hungary.
    • (L04) ROASTERR-1 Observatory, Cluj-Napoca, Romania.
    • (Q62) iTelescope Observatory, Siding Spring, Australia/NSW.
    • (T05) ATLAS-HKO, Haleakala, US/Hawaii.
    • (T12) Mauna Kea-UH/Tholen NEO Follow-U (2.24-m),US/Hawaii.
    • (W25) RMS Observatory, Cincinnati,US/Ohio.
    • (W88) Slooh.com Chile Observatory, La Dehesa,Chile.
    • (Y28) OASI, Nova Itacuruba, Brazil.
    • (Z80) Northolt Branch Observatory,UK..
  • Perihelion Distance: 0.6654428764236301  (AU)
  • Aphelion Distance: 2.013952506814137 (AU)
  • Earth MOID: 0.000339358 AU (0.132 (LD)) or 31,545.297 miles (50,767.234 (KM))
  • Close-Approach to Earth: Will safely pass Earth on 2016-December-16 at a Nominal Distance of  0.0538116295342834 (AU) (20.942 (LD)) or 5,004,610.672 miles (8,054,140.158 (KM))
To illustrate on how the addition of observation can lower the uncertainty of orbital elements here is three
screenshot of Find_Orb showing elements and their uncertainty
 
A screenshot of Find_Orb showing orbital elements and uncertainty
 before the addition of the precovery observation.
(2 observationobservation are rejected as outliers) 
Orbital elements:  2016 WJ1
   Perihelion 2017 Feb 7.453335 +/- 0.0146 TT = 10:52:48 (JD 2457791.953335)
Epoch 2017 Feb 16.0 TT = JDT 2457800.5   Earth MOID: 0.0004   Ve: 0.0023
M   5.42420715 +/- 0.0053           Ma: 0.0027                Find_Orb
n   0.63465774060 +/- 0.000456      Peri.   87.68828816 +/- 0.0057
a   1.34104390016 +/- 0.000642      Node    82.04709113 +/- 0.0023
e   0.5040907493 +/- 0.000384       Incl.    2.89419977 +/- 0.0022
P   1.55/567.22d           H 21.3   G  0.15   U  7.6  
q 0.66503607568 +/- 0.000196    Q 2.01705172465 +/- 0.00148
233 of 235 observations 2016 Nov. 19-Dec. 1; mean residual 0".32
 
A screenshot of Find_Orb showing orbital elements and uncertainty 
after the addition of the precovery observation.
(2 observationobservation are rejected as outliers) 
 
Orbital elements:  2016 WJ1
   Perihelion 2017 Feb 7.484044 +/- 0.000243 TT = 11:37:01 (JD 2457791.984044)
Epoch 2017 Feb 16.0 TT = JDT 2457800.5   Earth MOID: 0.0004   Ve: 0.0024
M   5.41286498 +/- 0.00015          Ma: 0.0027                Find_Orb
n   0.63561447057 +/- 1.52e-7       Peri.   87.67637253 +/- 0.00017
a   1.33969786518 +/- 2.14e-7       Node    82.05217334 +/- 0.00022
e   0.5032874712 +/- 8.64e-7        Incl.    2.88944734 +/- 0.000020
P   1.55/566.37d           H 21.3   G  0.15   U  2.3  
q 0.66544471439 +/- 1.26e-6    Q 2.01395101596 +/- 8.71e-7
238 of 240 observations 2003 July 4-2016 Dec. 1; mean residual 0".32
 
A screenshot of Find_Orb showing orbital elements and uncertainty 

with all published observation.
(2 observationobservation are rejected as outliers) 




Orbital elements:  2016 WJ1
   Perihelion 2017 Feb 7.484067 +/- 0.000172 TT = 11:37:03 (JD 2457791.984067)
Epoch 2017 Feb 16.0 TT = JDT 2457800.5   Earth MOID: 0.0004   Ve: 0.0024
M   5.41285007 +/- 0.00010          Ma: 0.0027                Find_Orb
n   0.63561448686 +/- 1.18e-7       Peri.   87.67634890 +/- 0.00015
a   1.33969784228 +/- 1.66e-7       Node    82.05222716 +/- 0.00017
e   0.5032875546 +/- 7.26e-7        Incl.    2.88944241 +/- 0.000019
P   1.55/566.37d           H 21.3   G  0.15   U  2.1  
q 0.66544459133 +/- 1.05e-6    Q 2.01395109323 +/- 7.49e-7
255 of 257 observations 2003 July 4-2016 Dec. 2; mean residual 0".31







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