Comet/asteroid Orbit Determination and Ephemeris Software (CODES)
Contents
1. 0 are seconds select Accept This Orbit Select Apply Differential Correction Select Try Another Method Select Try a Different Set of Three Observations Select Quit n EB 11 CODES Level Two Menu Compute an n body best fit orbit east squares with n body numerical MDN cometary thrusting if applicable solar radiation pressure solar oblateness gravitational perturbations including relativistic terms from the Sun nine planets Earth s Moon and up to 300 asteroids e Refines an initial two body orbit a statistical ranging orbit an imported orbit MPCORBcr file a user specified orbit e Allows observations to be excluded based on excessive chi or residuals CODES Level Two Menu Compute an n body best fit orbit results state vector plus covariances N derived orbital elements plus covariances residuals for each observation visual absolute magnitude and slope parameter if apparent magnitude observations are available estimate of the minor planet s radius asteroids only 1f visual absolute magnitude and slope parameter are available Minimum Orbital Intersection Distance NEOs only Warning for Potentially Hazardous Objects SkyMorph parameters formatted for easy input output to screen and text file CODES Level Two Menu Sample Valid Orbits Observational Monte Carlo e If least squares converges but observed are is very short the covariance ellipsoid may n2. sss dd mm ss ss VMag Degree ArcSec ArcSec Min Degree AUS AUS Degs 2004 02 02 00 00 00 0 05 18 17 611 20 21 14 13 19 0 73 9 218321 44225 2 1 49 2 0 5008 1 2745 114 1 2004 02 03 00 00 00 0 OS 20 58 726 19 48 34 45 19 1 73 8 211652 42879 2 1 49 2 0 5080 1 2807 114 2 2004 02 04 00 00 00 0 05 23 37 894 19 16 11 93 19 1 73 8 205359 41567 2 1 49 2 0 5154 1 2869 114 4 2004 02 05 00 00 00 0 05 26 15 214 18 44 07 18 19 1 73 7 199414 40288 2 0 49 2 0 5229 1 2932 114 5 2004 02 06 00 00 00 0 05 28 50 781 18 12 20 76 19 2 73 7 193787 39041 2 0 49 3 0 5305 1 2994 114 6 2004 02 07 00 00 00 0 05 31 24 687 17 40 53 18 19 2 73 6 188453 37828 2 0 49 4 0 5382 1 3057 114 7 2004 02 08 00 00 00 0 05 33 57 017 17 09 44 92 19 2 73 6 183384 36646 2 0 49 5 0 5459 1 3120 114 7 2004 02 09 00 00 00 0 05 36 27 856 16 38 56 40 19 3 73 5 178571 35495 2 0 49 6 0 5538 1 3182 114 8 2004 02 10 00 00 00 0 05 38 57 283 16 08 28 02 19 3 73 5 173981 34375 2 0 49 7 0 5619 1 3245 114 8 2004 02 11 00 00 00 0 05 41 25 376 15 38 20 15 19 3 73 5 169608 33285 1 9 49 8 0 5700 1 3309 114 8 Done CODES Level Two Menu Generate an optical ephemeris cont fb Comet Asteroid Orbit Determination and Ephemeris Software lolx JD 2004815000 10 204414 20 44 28 RA 27 CODES Level Two Menu Linear Collision Analysis Requires state vector and if impact probability desired covariances Algorithm e Propogate state vector forward from epoch to destfed end
3. 249029 U 5 0240482713912095 5 AU e 0 6807556325959969 1 5479251643453335E 4 1 21 216936507295076 deg ls 980039580983952E 4 deg w 341 05352993374294 deg lo 0017238805730052252 deg omega lass 88998359796402 deg 00222310543677841 deg T 2453041 2410775754 JD 0 0036837336259165337 days Optional Non Gravitational Thrust Parameters Al o o x 10 9 U day 2 n o x 10 9 AU day 2 A2 o o x 10 9 JU day 2 lo x 107 9 AU day 72 DT o o days Display State Vector Done 21 CODES Level Two Menu Manually specify an orbit for this minor planet User can specify either state vector or cum plus covariances Allows evaluation or adoption of non CODES derived orbits e Calculate residuals for comparison Provide initial orbit for best fit refinement e Calculate an ephemeris e Conduct a linear collision analysis Allows trial and error determination of DT cometary thrust parameter 22 CODES Level Two Menu mport a minor planet orbit from the MPCORBcr or COMET catalogs Allows CODES to read the orbital elementStel a minor planet directly from the appropriate MPC cat log Provide initial orbit for best fit refinement e Add estimated covariances e Add or determine cometary thrust parameters Calculate an ephemeris Conduct a collision analysis 23 CODES Level Two Menu Compare observations to positions of known minor planets catalog most nearly matching the obs
4. 7 0 0 90 704 2 1999 05 15 216550 12 27 02 520 1 00 0 85 04 30 32 50 1 00 0 20 16 9 0 87 704 3 1999 05 15 228450 12 27 05 370 1 00 0 39 04 29 28 40 1 00 0 22 16 6 0 45 704 4 1999 05 15 240160 12 27 08 410 1 00 0 45 04 28 25 00 1 00 0 09 17 4 0 49 704 5 1999 05 15 251880 12 27 11 450 1 00 0 41 04 27 21 60 1 00 0 17 17 3 0 44 704 Phys Props Done CODES Level Two Menu Propogate the current orbit to a new epoch fb minor planet 2000SG344 The Heliocentric Ecliptical Orbital Elements for TDB Epoch 2451545 0 Note Reference Frame is ICRF J2000 WARNING THIS IS A POTENTIALLY HAZARDOUS MINOR PLANET MOID lt 0 00132 omega Al A2 DT CODES element Jo 9833205094838733 AU fo 06579425803017226 Jo 10772636694447191 deg 271 69711392229465 deg 193 5269937488819 deg 356 15884529156483 deg covariance i 2467465626509274E 6 Au 3 6907248375787533E 6 7 998048787669914E 6 deg o 0018219877610450579 deg 0 0016101108064066746 deg 6 895639178179978E 4 deg Optional Non Gravitational Thrust Parameters o o x 10 9 AU day z o o x 10 9 Auf day z o o days Display State Vector o o x 10 9 AU day 2 o o x 10 9 AU day 2 Done 20 Level Two Menu Display Current Orbit minor planet P2003WC7 B x The Heliocentric Ecliptical Orbital Elements for TDB Epoch 2452961 638084748 Note Reference Frame is ICRF J2000 element covariance q 1 6548662247
5. Comet asteroid Orbit Determination and Ephemeris Software by J m Baer CODES In support of current minor planet surveys CODES combines an n body numerical integrator with a Graphical User Interface to provide the following capabilities Orbit determination based on optical and ine Calculation of topocentric or geocentric ephemerides Identification of known minor planets which most closely match a set of observations Linear and non linear collision analysis N body integrator accounts for cometary thrusting if applicable solar radiation pressure solar oblateness and gravitational perturbations including relativistic effects from the Sun nine planets Earth s Moon and up to 300 asteroids CODES CODES is an object oriented application Level One Menu Create Delete or Open instances of the class MinorPlanet Level Two Menu Add attributes observations Derive additional attributes orbital elements ephemerides collision analysis CODES Level One Menu S Level One Menu Level Two Menu Level Two Menu minor planet 2004be68 Generate Level Two Menu Designate the minor planet as a comet or asteroid e Should be the first change made to a neWminor planet file e Critically impacts Least squares best fit orbit Processing visual magnitude data Minor Planet Center MPC catalog search Orbital e
6. ample valid orbits Observational Monte Carlo Stat Rng Sample valid orbits Statistical Ranging Residuals Compute the observational residuals resulting from the current orbit Propogate Propogate the current orbit to a new epoch Er Ge Bra EL ELT teen Cancel Cancel Return to Level Two Menu CODES Level Two Menu Compute an initial two body orbit Gauss Method N Conditioned Gauss semi major axis constrained Laplace Method Herget s Method slant range constrained statistical Ranging slant range sampling Note This algorithm is located in a different menu but is a highly effective method of initial orbit determination especially for very short arcs CODES Level Two Menu Compute an initial two body orbit results minor planet 2000SG344 ojx Heliocentric Ecliptical Orbital Elements and Barycentric Equatorial State Vector of minor planet 200056344 for TDB Epoch 2451313 7055093355 Note Reference Frame is ICRF J2000 WARNING THIS IS A POTENTIALLY HAZARDOUS MINOR PLANET element component a 0 9774621047717332 AU x 0 611942516535645 AU o 07023876986777015 0 7518635373026731 AU lo 11500785897381362 deg 2 0 3245133008865904 AU w 265 0800178698802 deg xdot 0 012854580330584169 AU day omega 200 33615215468384 deg ydot 0 009822697784645075 AU day M 121 6103219509506 deg zdot 0 004226998135465775 AU day Residuals Obs 1 0 0 arc seconds N bs 6 0 0 arc seconds Obs 10 0
7. ervation ef this minor planet Use two body or n body mechanics E Select medium or high integration accuracy Narrow n body asteroid candidate search on basis of population NEA main belt Centaur TNO e absolute magnitude Generates a list of those minor planets in the EA or COMET For each entry Extracts orbital elements from catalog Predicts astrometric position at time of each observation Eliminated if either RMS residual gt 3 degrees e visual mag residual gt 2 Candidates output to screen and text file 24 CODES Level Two Menu Generate an optical ephemeris e Geocentric topocentric ne range of dates e Tabular presentation nominal values for each desired date K major axis minor axis orientation angle of linear covariance ellipse e Scatterplot presentation displays predicted RA Decs based on variant orbits generated by Observational Monte Carlo or Statistical Ranging Color coded by RMS residual of variant orbit to illustrate most likely positions Displays non linear observation space for precovery recovery 25 CODES Level Two Menu Generate an optical ephemeris cont Optical Ephemeris for minor planet 2004be68 Reference Frame is ICRF JZ000 position angles measured clockwise from due north Linear 3 sigma Ellipse pp Motion Relative Geometry DATE UTC RA DEC Pos ng SMj xs SMn xs ArcSec Posing Delta r Elng year mm dd hh mm secs hh mm ss
8. eturn create a dense sampling 100 VAs around minimum folding point look for collision nearest miss 29 CODES Level Two Menu Collision Analysis output to text and file fb minor planet 2004be68 TG x Hominal Minimum 3 sigma DATE UTC Miss Dist Miss Dist width Collision year mm dd hh mm secs Event Planet Als Als AUS Prob Sigma 2008 10 22 18 04 55 1 near miss Moon 0 002558 0 002408 0 0 0 3 2008 10 22 19 19 23 1 near miss Earth 0 00322 0 0024136 1 DE 9 0 3 2011 10 22 18 34 35 7 near miss Earth 0 003599 0 0025048 3 0E 9 0 6 2011 10 22 19 19 03 1 near miss Moon 0 0049 0 0025018 0 0 0 6 2013 10 23 01 50 03 0 near miss Earth 0 003098 0 0023884 4 0E 9 0 3 2016 10 22 04 32 21 5 near miss Moon 0 001107 0 0024604 0 0 0 5 2016 10 22 07 52 12 5 near miss Earth 0 001505 0 0024718 1 0E 9 0 5 2018 10 23 06 16 26 8 near miss Earth 0 003893 0 0023895 4 8E 8 0 3 2020 10 23 04 14 06 5 near miss Earth 0 005866 0 002 2749 0 0 0 2 2022 10 22 07 50 55 2 near miss Earth 0 007133 0 0025306 2 DE 9 0 7 Next Event Done CODES Level Two Menu Collision Analysis Considerations e Analysis generally similar to sila dn Chodas and Valsecchi in Asteroids III N e Results thus far comparable with Sentry and NEODyS Risk Page despite some algorithmic differences CODES collision analysis performed and results quoted in 3 space vs collision plane Trails defined slightly differently CODES differential correction performed al
9. lement display Use of cometary thrust in numerical integrator CODES Level Two Menu Adding an Observation e Manual entry of ground based optical observation Manual entry of radar observation e Parse and process Minor Planet Electronic ircular MPEC or Minor Planet Center Observation MPCOBS file e Parse and process Near Earth Object Dynamic Site NEODyS ASCII observation file e If International Earth Rotation Service IERS Earth Orientation Parameter EOP file not available for observation epoch manual entry or default EOPs used note observations supported in period 1900 2200 CODES Level Two Menu Review Delete Existing Observations ol f minor planet 2004be68 Select the observation s to be deleted bservations l 5 of 28 Total Number of Optical Observations Total Number of Delay Observations Total Number of Doppler bservations 28 0 0 RA DELAY DEC DOPPLER 05 01 40 510 23 39 36 30 OBS UTC DATEH H 1 2004 01 27 093210 E 2 2004 01 27 105520 05 01 42 580 23 39 10 90 a 3 2004 01 27 117870 05 01 44 690 23 36 45 70 4 2004 01 27 130560 05 01 46 680 23 38 20 10 5 2004 01 27 142870 05 01 48 910 23 37 55 10 Delete Checked Next 5 Done CODES Level Two Menu Compute Evaluate Propogate the orbit of this minor planet minor planet 2004be68 lolx minor planet 2004be68 Compute an initial two body orbit Best Fit Compute an n body best fit orbit Obs MC S
10. nal Monte Carlo Trajectories are integrated from epoch to desired endpoint collisions near misses are noted but no use of trails Impact probability determined simply as number of impacting trajectories total number of trajectories e Most useful for cases such as AL00667 2004 AS1 when threat assessment 1s required but only a very short Observation arc 1s available CODES 33 Level Two Menu Change the number of perturbing bodies Determines what perturbing bodies d n body numerical integration Sun Moon nine planets Sun Moon nine planets Ceres Pallas and Vesta default Sun Moon nine planets and 235 asteroids much slower processing Sun Moon nine planets and 300 asteroids e Much slower processing CODES uses e JPL DE405 Planetary Ephemeris e Mean asteroid orbital elements 34 CODES Level Two Menu Set the radius visual brightness parameters Useful if orbital elements are ee slope parameter and absolute magnitude otherwise unavailable allows estimated visual magnitudes in ephemerides e Radius critical in processing bounce point of radar observations usually determined from visual brightness data as part of best fit orbit determination if no brightness data should be set manually prior to orbit determination e default is 1 km comets set to estimated bounce point coma radius 35 CODES System and Software Requirements CODES is wri
11. nt minor planet 2004be68 lolx Statistical ranging survey for minor planet 2004be68 Create 100 candidates lv Require prograde orbit lv Require e lt 1 0 lv Require RMS optical residuals lt 2 0 arc seconds Set rho min o o AUs Set rho max 6 0 Aus Use two body mechanics C Use n body mechanics Begin Statistical Ranging Survey Begin Note that this will be a lengthy calculation Please be patient Cancel Return to Level Two Menu Cancel 17 CODES Level Two Menu Sample Valid Orbits Statistical Ranging cont e Variant orbits can be N displayed in color coded scatterplots to illustrate non linear solution space used to generate ephemeris scatterplots for precovery recovery used for Monte Carlo collision analysis e Only reliable approach for very short arc cases Reveals multiple solutions Robust orbit and ephemeris uncertainty spaces Allows collision analysis when no best fit orbit is available CODES Level Two Menu Compute the observational residuals resulting from the current orbit minor planet 2000SG344 lolx Computed Observational Residuals for minor planet 200056344 Observations 1 5 of 31 RMS Optical Residuals 0 42 arc seconds RMS Delay Residuals 0 0 microsecs RMS Doppler Residuals 0 0 Hz OBS HUTC DATE RA DELAY rms resid DEC DOPPLER rms resid VMAG CHI OBS 1 1999 05 15 204820 12 26 59 590 1 00 0 90 04 31 35 30 1 00 0 03 1
12. ong LOV CODES uses dense sampling rather than interpolation Independently derived epoch state vectors and covariances 31 CODES Comparison CODES vs Sentry vs NEODyS 2004 BE68 with 39 observations 2004 Jan 27 09321 to 2004 Feb 01 48334 Predicted 1 sigma Collision LOV Date Miss Dist width Probability Sigma UTC er er 2008 1022 805 75 5 18 9 1 0E 9 0 3 2008 1022 895 72 0 20 1 T4E 10 08 20111022 774 844 19 6 3 0E 9 0 6 20111022767 86 5 21 1 2 5E 11 14 20131023 076 72 7 18 7 4 0E 9 0 3 2013 10 23 074 70 8 20 1 48E 10 08 2016 10 22 328 35 3 19 3 1 0E 9 0 5 2016 10 22 32 26 0 142 6 4E 8 1 2 2016 10 22 313 364 20 8 2 4E 8 1 2 2018 10 23 261 91 3 18 7 4 8E 8 0 3 2021 10 22 681 11 0 20 6 9 0E 8 1 1 2022 10 22 327 167 3 19 8 2 0E 9 0 7 20241022201 64 2 19 4 0 0 0 5 2024 10 22 190 66 9 20 8 3 0E 10 1 3 2026 10 23 018 23 46 8 0 0 0 4 2026 10 23 01 12 13 9 5 3E 8 1 1 2026 10 23 013 1 8 20 4 9 0E 8 1 1 20291022521 14 6 19 2 0 0 0 5 2029 10 22 50 8 3 14 2 1 8E 8 12 2029 10 22 501 11 6 20 7 2 9E 8 1 2 2031 10 23 322 0 0 27 5 1 0E 9 0 4 2031 10 23 31 0 1 13 8 4 8E 8 Et 2031 10 23 322 1 1 18 5 8 1E 8 1 0 I 2034 10 22 905 28 8 19 4 0 0 0 5 2034 10 22 87 20 9 14 1 3 2E 8 1 2 2034 10 22 867 29 3 20 6 2 0E 8 1 2 CODES Level Two Menu Collision Analysis Statistical Ranging e A Monte Carlo collision analysis M WR available for use with trajectories generated by Statistical Ranging or by Observatio
13. ot accurately repr sent the solution space this option directly samples the space of valid ofbats Add Gaussian uncertainty to each observation Apply least squares to derive variant orbit Default setting Create 100 variant orbits e Variant orbits can be displayed in color coded scatterplots to illustrate solution space qvs e qvs 1 qvs w qvs Q qvs M e Variant orbits can be used to generate ephemeris scatterplots for precovery recovery for Monte Carlo collision analysis CODES Level Two Menu Sample Valid Orbits Observational Monte Carlo cont Comet Asteroid Orbit Determination and Ephemeris Software Epoch 2453017 831213378 TDB 358 0 CODES Level Two Menu Sample Valid Orbits Statistical Ranging samples the non linear space of valid orbits e Used for very short arcs in place of iiia Deis directly Randomly generate slant ranges for first and last observations based on user specified min max slant range Combine with first last observations and observer positions to create two position vectors Use Gauss sector triangle ratios two body or Herget s method n body to derive state vector Compare predicted RA Decs to observations accept if RMS residual less than user specified threshold e User can optionally require only prograde elliptical orbits e User specified number of variants generated CODES Level Two Menu Sample Valid Orbits Statistical Ranging co
14. point at end of each integration step test distance to each possible target Sun Moon nine major planets if distance lt target radius gt collision use bisection to isolate propogate covariances to determine impact probability else if distance gt target radius and distance lt user specified threshold and first derivative changes sign use bisection to isolate minimum if distance at minimum lt target radius gt collision use bisection to isolate propogate covariances to determine impact probability if distance at minimum gt target radius gt near miss propogate covariances to determine impact probability 28 CODES Level Two Menu Non Linear Collision Analysis Primary options requires state vector and covariances plus all observations Algorithm N Creates user specified number of Virtual Asteroids Distributed normally in observation space about the nominal state vector Spaced along the Line of Variations e Each VA propogated forward from epoch to desired end point collisions near misses noted as in linear analysis events with scaled moid 3 sigma width of covariance ellipse lt threshold are sorted by target date and stretching into trails The minimum approach or folding point for each trail is retained use differential correction to test for collision near miss if differential correction fails or in case of an interrupted r
15. tten in pure Java compiled byte e will run on any system for which a Sun Virtual Machine exist System Requirements e approximately 150 MB of disk storage including DE405 files 256 MB or greater RAM internet access for download of observation files MPC catalogs EOP files and updated ObsCode files Software requirements all available for free download Java 1 4 1 or higher runtime environment compiled CODES bytecode and optional source code JPL DE405 planetary ephemeris files ASCII versions IERS Earth Orientation Parameter files 36 CODES Where can find CODES Web site s home sans Nd Fully documented User s Manual Links to all required software Suggestions for future enhancements are welcome jimbaer earthlink net 37 CODES
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