2021 KT21 and 2004 GZ13

Backward simulation performed with Mercury6 ``A Hybrid Symplectic Integrator that Permits Close Encounters between Massive Bodies''. Monthly Notices of the Royal Astronomical Society, vol 304, pp793-799. 

Simulation based on nominal orbital paramters (21st March 2024)

Simulation parameters

)O+_06 Integration parameters  (WARNING: Do not delete this line!!)

) Lines beginning with `)' are ignored.

)---------------------------------------------------------------------

) Important integration parameters:

)---------------------------------------------------------------------

 algorithm (MVS, BS, BS2, RADAU, HYBRID etc) = BS

 start time (days)= 2460309.50000 

 stop time (days) = -1e8

 output interval (days) = 100

 timestep (days) = 0.05

 accuracy parameter=1.d-12

Simulation Result

Following a comment from Adrien Coffinet, here is a forward simulation to show that as correctly guessed, the two asteroids might be again in a similar orbital configuration about 20K years from now:

2023 SP50 and 152737 (1998 WF28)

 Backward simulation

Mercury6 package by J.E.Chambers (1999) ``A Hybrid Symplectic Integrator that Permits Close Encounters between Massive Bodies''. Monthly Notices of the Royal Astronomical Society, vol 304, pp793-799. 

)---------------------------------------------------------------------

) Important integration parameters:

)---------------------------------------------------------------------

 algorithm (MVS, BS, BS2, RADAU, HYBRID etc) = BS

 start time (days)=  2460106.5

) stop time (days) = 102458000.5

 stop time (days) = -1e8

 output interval (days) = 100

 timestep (days) = 0.05

 accuracy parameter=1.d-12

Result

2022 QZ273 and 2002 RZ12

Backward simulation

Mercury6 package by J.E.Chambers (1999) ``A Hybrid Symplectic Integrator that Permits Close Encounters between Massive Bodies''. Monthly Notices of the Royal Astronomical Society, vol 304, pp793-799. 

)---------------------------------------------------------------------

) Important integration parameters:

)---------------------------------------------------------------------

 algorithm (MVS, BS, BS2, RADAU, HYBRID etc) = BS

 start time (days)=  2460106.5

) stop time (days) = 102458000.5

 stop time (days) = -1e8

 output interval (days) = 1

 timestep (days) = 0.05

 accuracy parameter=1.d-12

Result

2015 TB430 and 1997 YF7

 Interesting couple.

Simulation based on nominal orbital parameters 

Mercury6 software

)---------------------------------------------------------------------

) Important integration parameters:

)---------------------------------------------------------------------

 algorithm (MVS, BS, BS2, RADAU, HYBRID etc) = BS

 start time (days)=  2460106.5

) stop time (days) = 102458000.5

 stop time (days) = -1e8

 output interval (days) = 100

 timestep (days) = 0.05

 accuracy parameter=1.d-12

Simulation result

2023 SV69 and 2001 US116

 Backward integration based on nominal orbit performed with Mercury6 software

358P/PANSTARRS and 292547 (2006 TE55) and 300233 (2006 YX8)

                          a         e        i       om        w        q
  358P/PANSTARRS   3.146644 0.2388745 11.06014 85.70234 299.7696 2.394991
292547 (2006 TE55) 3.140893 0.2428301 11.11777 88.23864 298.1447 2.378189
300233 (2006 YX8)  3.138883 0.2418392 11.21893 87.87625 301.6746 2.379778

Backward simulation done with Mercury 6 

)---------------------------------------------------------------------

) Important integration parameters:

)---------------------------------------------------------------------

 algorithm (MVS, BS, BS2, RADAU, HYBRID etc) = BS

 start time (days)=  2460106.5

 stop time (days) = -1e8

 output interval (days) = 100

 timestep (days) = 0.05

 accuracy parameter=1.d-12

Plots

313P/Gibbs and 2016 JM83

Backward simulation (up to about 300K years ago)

313P/Gibbs and 2016 JM83 have a very similar orbit, they never came very near each other, the two orbits are stable: